Biodiversity Net Gain: Key guidance and secondary legislation published

2024 is set to bring big changes to development law with Biodiversity Net Gain (BNG) measures becoming mandatory for most developments in England from 1st January. Small sites will not be subject to BNG laws until April 2024, while laws pertaining to Nationally Significant Infrastructure Projects (NSIPs) are expected to come into force in November 2025.

East Devon View by Alison Day via Flickr.
The Biodiversity Net Gain timeline to date

Following the Environment Act 2021 receiving royal assent in November 2021, provision was made for BNG to be introduced in England commencing in 2023. It was set out that gains could be delivered onsite, offsite or through the purchase of biodiversity credits.

In February 2023, Defra published its consultation response which provided more details on how BNG would be implemented, and suggested that the law would come into effect in November 2023. This has now been revised to January 2024.

At the end of September 2023, Defra and the Department for Levelling Up, Housing and Communities (DLUHC) published a timetable for the introduction of BNG. They also confirmed that it would only apply to new planning permission applications and not applied retrospectively to applications submitted prior to 1st January 2024.

This week, on 29th November, key guidance documents and secondary legislation were published by the Government.

Guidance documents

Step-by-step guidance has been provided for developers, land managers and local authorities which lead users through the BNG process.

Guidance for developers includes information on measuring the impact of a specific development on biodiversity, deciding how to achieve BNG, and ensuring that the 10% gain is maintained for at least 30 years.

Guidance for land managers looks at the options available for their land type and quantity, preparation and selling of biodiversity units, registering and recording the sale of the units to a developer, and the subsequent long-term management of the habitat.

Guidance for local authorities includes information on setting local policies to support biodiversity net gain, approving planning applications and biodiversity gain plans, reviewing the biodiversity gain plan, checking metric calculations and habitat surveys, checking developers selling excess on-site gains, checking the biodiversity gain sites register for off-site gains, monitoring BNG, and working with developers who wish to buy statutory biodiversity credits.

New housing estate in Stowmarket by Andrew Hill via Flickr.
Secondary legislation

Secondary legislation are laws that add more detail to primary legislation, allowing them to be enacted and enforced. In the case of BNG, these laws will provide the practical details required for measures to be implemented under the primary legislation of the Environment Act 2021.

Statutory instruments (SIs) are the documents created that must be laid in Parliament before the law can be changed. There are six BNG statutory instruments that will need to be approved by Parliament before they can be brought into effect on 1st January. These include:

The Biodiversity Gain (Town and Country Planning) (Consequential Amendments) Regulations 2023 – These regulations make amendments to the existing primary legislation on planning so that the BNG framework can be included.

The Biodiversity Gain Site Register (Financial Penalties and Fees) Regulations 2023 – This allows for fees to be incurred when registering land in the biodiversity gain register and financial penalties to be charged where incorrect information is provided.

The Biodiversity Gain Site Register Regulations 2023 – This sets out the details and eligibility criteria for the creation of a publicly available “biodiversity gain site register”. The register will be established and maintained by Natural England.

The Biodiversity Gain Requirements (Exemptions) Regulations 2023 – This sets out the categories of development that are exempt from creating biodiversity net gain.

The Biodiversity Gain Requirements (Irreplaceable Habitat) Regulations 2023 – This lists the habitats that are considered irreplaceable and for which the standard 10% requirement will not be applied.

The Biodiversity Gain (Town and Country Planning) (Modifications and Amendments) (England) Regulations 2024 – These regulations details how the BNG process will work within the existing planning application procedure. It also includes details of how appeals should be made.

The first two SIs were laid in Parliament on 30th November and will shortly be published on the Government’s legislation website. The remaining four still require approval by Parliament, although draft versions can be viewed using the links above.

Wild flower meadow by gailhampshire via Flickr.
Next steps

In January 2024 BNG will become mandatory for new applications for planning permission, with the exclusion of small sites* where BNG will not need to be delivered until April 2024, and NSIPs which will be covered from November 2025.

Having lost nearly half of our biodiversity since the 1970s, the UK is one of the most nature-depleted countries; we are ranked in the worst 10% globally for biodiversity intactness. Overall, 41% of species in the UK have declined in the last 50 years, with 26% of mammals at risk of extinction. We’ve lost 97% of our meadows, 90% of our wetlands and 80% of lowland heathland.

A scheme where development will no longer lead to biodiversity loss, but instead to net gain, is a step in the right direction to preventing further loss and helping to begin repairing our degraded environment.

* (Small sites are defined as (i) For residential: where the number of dwellings to be provided is between one and nine inclusive on a site having an area of less than one hectare, or where the number of dwellings to be provided is not known, a site area of less than 0.5 hectares. (ii) For non-residential: where the floor space to be created is less than 1,000 square metres OR where the site area is less than one hectare.).

Further reading

NHBS blog: Biodiversity Net Gain – Information about the scheme, including who will be affected, how it will be measured and potential barriers to its effectiveness.

NHBS blog: Biodiversity Net Gain: Credit Creation and Metric 4.0

Defra land use blog – articles on everything relating to BNG.

Government guidance on BNG

This week in biodiversity news – 27th November 2023

Climate Crisis

Plants may absorb more CO2 from human activities than previously thought, according to new research. More realistic modelling that considers critical physiological processes inside plants paints a more positive picture than previous predictions. The efficiency of carbon transport in plant leaves, the ability of plants to adjust to changes in temperatures, and how plants distribute nutrients in the canopy, often ignored in climate modelling, were examined in this study. Scientists stress that simply planting more trees is not a silver-bullet solution, but that the research does underline the importance of efforts to conserve existing vegetation.

Beach forest
Beech forest by Picccus via Flikr.

Red alerts have been issued as Brazil suffers an unprecedented heatwave. Temperatures are likely to remain 5°C above average for longer than five days and could pose a serious danger to human health. Rio de Janeiro recorded 42.5°C, breaking November records, and due to high humidity felt like 58.5°C according to authorities. The heatwave has been attributed to a combination of the El Niño climate phenomenon and climate change. The human impact of such extremes is significant with “unbearable” temperatures leading to sleepless nights, exhaustion, illness and death.

Pollution

Most bathing spots in English rivers and lakes have unsafe pollution levels, according to a new report. The campaign group Surfers Against Sewage took a sample of popular swimming and water sports locations and found that 60% had unsafe levels of pollution. This year across the UK, untreated sewage was discharged 399,864 times into waterways, resulting in a reported 1,924 cases of illness. The report highlighted the case of a physics teacher from Exeter who contracted an incurable disease known as Ménierè’s disease after surfing at Saunton Sands in Devon. 

flooded river
River Windrush by Dave_S via Flickr.

The high court has ruled that Defra’s failure to protect and restore water bodies is ‘unlawful’. Fish Legal and Pickering Fishery Association took the government to court over its river basin management plan for the Costa Beck, a small river in Yorkshire. They argued that the Environment Agency had failed to follow through with proposed action against polluters. The judge accepted discharges of pollution were contributing to the poor condition of the river and that the government and Environment Agency had failed in their mandatory duty to put in place measures to restore rivers under the Water Framework Directive.

Extinction Risk

Blue Whales have returned to safe havens in the Indian Ocean where they were wiped out decades ago. Underwater recordings made by researchers in the Seychelles revealed that the whales spend months in the region, suggesting that they may be breeding there. The discovery has been hailed as a “conservation win” given the decimation of whale populations by commercial whaling. More than 300,000 Blue Whales were killed by whalers in the southern hemisphere with around 30,000 killed in a single year during the 1930’s. A crackdown on commercial whaling in the 1980’s brought the species back from the brink of extinction; however, Blue Whale numbers remain a fraction of what they once were before the development of industrial whaling operations in the 20th century.

blue whale tail
Blue Whale surfacing by Kenny via Flickr.

New research has revealed that there is a significant threat of future waves of invasive species. Biological invasions can cause extinctions, spread diseases and cost trillions in damage and control. Researchers found that, on average, around 1% of all living organisms have been transported by humans somewhere in the world. The study indicates a huge potential for future biological invasions with an expected rise in associated socio-economic and environmental impacts.

Conservation

A hedgehog fence in Dorset is helping to protect threatened seabird chicks. Little Terns are one of the most threatened seabirds in the UK and the RSPB’s Chesil Little Tern Recovery Project seeks to reverse its decline. Trail cameras had revealed that hedgehogs had been eating Little Tern eggs. Given the protected status of hedgehogs, the project worked with the charity Hedgehog Friendly Portland to design a hedgehog fence and implement diversionary feeding. At least 45 Little Terns successfully fledged at Chesil Beach in 2023, compared with just three in 2021.

hedgehog looking out from a bush
Hedgehog by Kalle Gustafsson via Flickr.
Policy

The US will outline its nuclear fusion power strategy at COP28. John Kerry, the US Special Envoy on Climate Change, will set out the plan at the UN summit that will be held in Dubai from the 30th of November. The plan has been described as being the first international strategy for nuclear fusion power commercialisation. Nuclear fusion has long been looked at as a potentially limitless source of clean energy.

Read the last edition of Biodiversity News from the NHBS Blog which follows stories on endangered echidnas and an explosion in jellyfish numbers.

Why a trail camera makes the perfect gift this Christmas

Badger image taken with the Browning Spec Ops Elite HP5

Choosing the right gift for friends and loved ones can be a tricky affair, but for any keen wildlife watcher, and particularly one with a fondness for photography, a trail camera could be the perfect option. Here’s just a few reasons why we’re fans:

1. Catch a glimpse of wildlife that you wouldn’t otherwise be able to see
An obvious one perhaps, but trail cameras give you a wonderful opportunity to see and capture footage of all sorts of wildlife, particularly species that are easily startled or those that are active at times when we’d prefer not to be out and about (such as in the middle of the night) – a trail camera will allow you to observe the hidden lives all around you. The video below, recorded with the Browning Recon Force Elite HP5, is a wonderful example of what you can achieve right outside your back door.

2. See what animals are up to at times when you wouldn’t usually be watching
A perfect example of this is observing nocturnal animals. While the hardiest wildlife watcher might not be averse to wandering the fields and woods in the middle of the night equipped with the latest night vision gear, most of us would prefer to be tucked up in our beds. Trail cameras, with their night vision technology, can take images and videos of all the action so you can view it later at a time that’s more convenient. The video below shows a young fox passing through at night, recorded using a  Browning Recon Force Elite HP5 by Two J’s Wildlife Camera Set in Cornwall.

3. View behaviours and interactions that are usually unseen
While nothing beats an in-person encounter with a wild animal, such experiences are often brief and offer us limited insight into their life. Trail cameras, particularly those equipped with no-glow night vision technology (which means there is no tell-tale red flash when they take a photograph), are inconspicuous and will record footage for as long as there is movement within their capture range. This means that they are great for letting us experience a much broader range of behaviours and interactions. The video of the squabbling squirrels below was recorded by Two J’s Wildlife Camera Set in Cornwall.

4. Create stunning time-lapse videos
Almost all trail cameras can be programmed to capture images at a time interval of your choice, regardless of whether there is any movement detected. Using this function makes it possible to capture the subtle and gradual changes in the environment that would be difficult to observe in real time. Similarly, they can also be used to record behaviours that take place over longer periods, allowing you to view them at an accelerated speed.

A wren sitting on a branch in scrub.
A Wren photographed using the Browning Strike Force Pro X 1080

5. Share your findings with others
Whether you’re conducting research or simply want to know what’s happening in your back garden, the images and videos from a trail camera are perfect for sharing your findings with friends, family and colleagues. The quality of the photos/videos can be impressive, particularly when using models with high resolution lenses.

Browse the full range of cameras available from NHBS at nhbs.com.

For more advice about choosing a camera to suit your needs and budget, why not take a look at our Trail Camera Buyer’s Guide or contact us to chat with one of our experienced Wildlife Equipment Specialists.

In The Field: Browning Strike Force Pro X 1080

At NHBS, we offer trail cameras from a range of different manufacturers. Among these is Browning, who offer high quality at a reasonable price. The Browning Strike Force HD Pro X was one of our most popular cameras, and we regularly recommended it to customers. It offered ease of use, affordability, and excellent daytime and night-time photography. Browning regularly update their range of trail cameras, and given that the Strike Force has been on the market for several years, it has likewise been upgraded to a newer model, the Browning Strike Force Pro X 1080.

Trail camera with camouflage facing the camera with white background.
The Browning Strike Force Pro X 1080.

We wanted to test out the new Browning Strike Force trail camera to ensure it lives up to the standards of its predecessor. Here we will detail how we tested this camera and what we found.

Set up

To test the Strike Force, we headed to an estate in Devon that is managed to improve the condition of wildlife.

The set-up was relatively simple; we found a clearing between two areas of scrub where we suspected that animals would pass through, and secured the camera to a small tree at around waist height using a Python Lock.

The Strike Force comes with a camera strap included which works excellently, but we would recommend purchasing extra security options like a Python Lock if you are placing your camera in a public place. The strap and Python Lock can fit around a tree or a fence post and be tightened to hold the trail camera in position.

I set the camera to default settings and then changed it to photo mode and set the multi-shot option to three photos. I wanted to leave the camera out for a significant length of time, and I knew that videos would drain the battery and fill up the memory card rapidly. The multi-shot mode would hopefully allow me to get a few pictures of an animal moving through the frame.

Results

After three months in the field, the results yielded surpassed our expectations. We knew from talking with the conservation manager at the estate that we might get some decent pictures, but the range of species was unexpected.

The trail camera captured pictures of a range of bird species including one of a buzzard in flight.

Buzzard in flying past bushes.
A buzzard in flight.

We were lucky enough to get an amazing shot of a deer reaching for a leaf from the swaying branch of a willow tree as well as an excellent night time photo of a deer.

Deer reaching for a willow leaf.
A deer reaching for a willow branch.
Deer in a field at night. IR image.
A night-time image of a deer using IR photography.

A herd of Belted Galloway cattle were spotted passing through the clearing.

Cows with white stripe walking through a field with bushes around.
A herd of Belted Galloway cattle pass by the camera.
A herd of striped cows pass by the camera with calves in tow.
A Belted Galloway calf.

This herd of cows were curious and ended up nudging the camera with their noses, causing the camera to face towards a bush. We then caught a glimpse of a fox with the infrared camera mode. The image is a bit overexposed due to the vegetation in the foreground.

IR image of vegetation in the foreground and the faint image of a fox in the background.
A fox passes through the clearing.

Despite the overexposure, many of the IR pictures were excellent.

IR picture of vegetation in the foreground with two deer in the background passing through a clearing in the vegetation.
Deer at night.

We even managed to get a picture of what looks to be a Barn Owl on the ground at night. While not very clear due to the overexposure, it certainly confirms its presence in the area.

Vegetation with a barn owl on the ground in the background in IR photo mode.
A sighting of a Barn Owl on the ground.

The cows came back and pushed the trail camera even further to the right so that it was pointing into a bush. Fortuitously, we managed to get pictures of a mouse, a Robin and a Wren.

An IR photo of a mouse climbing a stick in foreground to the right of the image and vegetation in the background.
A night-time photo of what looks to be a Field Mouse.
Robin sitting on a branch surrounded by vegetation.
A Robin sitting in scrub.
A wren sitting on a branch in scrub.
A Wren sitting in the same spot as the Robin.

In addition to the species featured above, we also captured pictures of butterflies, squirrels, pheasants, Wood Pigeons, a thrush and a Great Tit.

Performance

When sorting through the 5,500 photographs captured, I found that the vast majority didn’t show any animals. I suspect that this could be remedied by better camera placement, although this may be unavoidable if there is a lot of vegetation around the area you wish to monitor. The major downside of taking so many photographs is that it takes a long time to sort through, and could potentially fill up your storage too quickly if you set your camera to video mode.

The image quality was impressive, with high-quality images and limited motion blur. The most notable issue was the level of exposure in the images, mainly at night. This was largely an issue because a herd of curious cows nudged the camera so it was facing the edge of a bush. This is unlikely to be a problem in the majority of cases and, prior to this, the night pictures were excellent.

Longevity

We placed the camera in the field in mid-July and collected it in mid-October. As such we were able to get around three months of footage. Image quality was set to 24MP with 1.5–2.5MB of storage used per image and around 5,500 images in total. This meant that we only used around 11GB out of a total of 32GB of storage available on the SD card. Remarkably, when the camera was collected it registered 94% battery, demonstrating the longevity of the Strike Force in the field, especially when set to photo mode. I suspect that this camera could have been left for another three months in the field without running out of storage or battery power.

Verdict

Overall, our experience demonstrates that the Strike Force Pro X 1080 is an impressive trail camera with high-quality day and night footage and impressive longevity. While it perhaps doesn’t quite reach the heights of the Browning Recon Force Elite HP5 or the Bushnell Core DS-4K in terms of picture quality, a more affordable price and impressive performance make this camera highly recommendable for both professionals and hobbyists.

No-glow alternative camera – Browning Dark Ops Pro X 1080

The Browning Strike Force Pro X 1080 is a low-glow camera meaning that the glow from the IR bulbs can be seen by both humans and animals. A no-glow camera may be the best option if you are looking for extra security or photographing an easily alarmed species. The Browning Dark Ops Pro X 1080 is an ideal no-glow alternative to the Browning Strike Force Pro X 1080. While a little more expensive, it is stealthier, and humans are less likely to notice it due to its no-glow flash. The only disadvantage is the shorter 24m flash range of the no-glow bulbs compared to the 36.58m flash of the Strike Force.

Trail camera facing towards the camera with camouflage coating with a white background.
The Browning Dark Ops Pro X 1080.
Accessories

The Python Lock is an ideal accessory for your trail camera. It won’t stop your camera from being damaged but it will prevent theft and keep your camera securely fastened to a tree or post. The lock is anti-picking, weatherproof and vinyl-coated. We used a Python Lock, and it held the camera in place until a herd of cows decided to turn it.

Image of a coiled up python lock.
Python Lock.

Spare memory cards and batteries are also highly recommended, especially if you are planning to use your trail camera on video mode. These additions will help you keep your camera operational for longer. Lithium batteries are highly recommended as, even when they have low charge levels, they supply sufficient power to the trail camera. Users of alkaline batteries may find that their trail camera isn’t performing well at night; this is because the batteries are not supplying sufficient power for the IR bulbs to function correctly.

 

Get your Browning Strike Force Pro X 1080 from our online shop.

Hawke Digi-Scope Smart Phone Adapter

Hawke DIGI-SCOPE SMART PHONE ADAPTER with a binocular lens attached being used to take a photograph of a black and white bird in the grass.

Getting into nature photography can be a daunting prospect. What camera do you buy? Which lenses do you choose, and what size should they be? How much should you spend? These are all questions that require a good bit of thought, and rightly so. However, what if you wanted to dip your toe in at the shallow end and use equipment that you may already have lying around to take decent photos at a fraction of the price? That’s precisely where the Hawke Digi-Scope Smart Phone Adapter comes in. I decided to put it to the test by taking images of local wildlife at a variety of ranges with two of Hawke’s spotting scopes and a pair of Kite binoculars. To do this, I used the Hawke Nature-Trek 20–60 × 80 and the Nature-Trek 13–39 × 56 scopes, and a pair of Kite Ursus 8 × 32 binoculars. 

Hawke have established a name for themselves as producing reliable and rugged optics for the entry to mid-level markets and this optical adapter fits nicely into that niche, giving anyone with an optical device the option to transform their optics into a camera lens, when combined with a smartphone camera. 

Out of the box – first impressions 

The adapter comes packaged with a small instruction manual and some small foam sticky pads to place around the aperture clamp and prevent damage to the ocular lens of the optics you are using. Made from lightweight ABS plastic, the adapter feels light in the hand but not fragile. Stated compatibility on the box is for eyepieces 23–50mm in diameter, so make sure that the optics you plan to use meet these specifications. There is also a minimum and maximum size for compatible phones (width 66–95mm), but most currently produced models should fit fine.

Front and back of the black scope phone attachment.

Ease of use  

The adapter is a simple piece of kit that is designed to fit around the ocular lens of a spotting scope, microscope, telescope or, most commonly, a pair of binoculars. The spring-loaded clamp then allows you to place your phones rear camera to the eyepiece and align them, in essence creating an inexpensive camera and physical lens arrangement. This will then allow your smartphone to take photos at ranges that the vast majority of devices on the market wouldn’t be capable of. Getting this alignment right can be quite fiddly but once found, the adapter holds fast, and the point of focus doesn’t drift. It’s important to try to remember to reduce/disable the auto focussing on the device as this can be at odds with the manual focus of the scope itself. Likewise, make sure to zoom the phone camera slightly to avoid giving a ‘scoped’ view to your photos, with a circular black border (see below).

Photograph taken through the scope attached to a phone of some ducks in a garden with a black ring around it in the shape of the lens. Photograph taken through the scope attached to a phone of some ducks in a garden without a black ring the shape of the lens around it, focused nicely and closely on the ducks.

In the field 

Testing the adapter involved setting it up on the window ledge of a bird hide and using it while combing along the River Dart, allowing tests over variable distances to look and capture at different focus points and ranges. I often found that target acquisition with the scopes was a bit of a lesson in trial and error as any hand movement through high magnification lenses will be exacerbated massively through the screen. However, this will be greatly reduced by using a lesser magnification or a stabilising structure such as a tripod (or a handy fence post). The use of a phone in this case proved crucial as the post- processing from the device helped to mute the amount of disturbance to the final image from this unavoidable shaking. While there was some aberration introduced to the final photos, it didn’t mar the result too much or overly distract from the images (see below). 

Photo of a mallard duck swimming on the river by some reeds taken through the Hawke smartphone adapter. Photo of a duck flapping its wings and splashing on the river by some reeds with a vignette image border taken through the Hawke smartphone adapter.

Using the adapter with a pair of binoculars was where the Hawke Digi-Scope really shone. Quick to acquire and quick to capture, the photos produced were, in my opinion, superb, making this an ideal tool for an enthusiast beginning their journey into nature photography. (see images below) 

Zoomed in photograph of a squirrel on a grey and red roof. Photograph of a crow on some grass which is scattered in autumn leaves.

While the adapter itself is a lightweight bit of kit, whatever you mount within it will add weight to the back of your optics and upset any built-in centre of balance – much as I found out when, after attaching the phone, the scope made a determined attempt at see-sawing off the bird-hide window ledge. When not attached to the optics, however, the adapter is small and portable, fitting easily into a pocket without any discernible bulk or weight. 

Taking pictures with the adapter was as simple as hitting the camera button on the phone and snapping away, making sure to adjust the focus using the scope/binoculars as needed (this took a bit of practice to get used to). I didn’t manage to get any images of animals moving at great speed (something a dedicated nature photography camera would have no issues doing) while using the scopes, as acquiring and holding onto the target while also focusing using the scope lent itself to more stationary birds (see image 9). The binoculars, on the other hand, were great for reactive type photography, albeit at much reduced ranges (e.g. image 10). 

Photograph of a brown duck standing on one leg scratching the underside of its wing with its beak stood on a log taken through a lens.
Image 9
Motion photograph of a crow taking off in flight from a patch of grass scattered in autumn leaves.
Image 10

 

 

 

 

 

 

Conclusions

While using the Hawke Digi-Scope, it is important to remember that the phone you use, the post processing that it does, and the settings you enable will all modulate the end result in some way, and this is an unavoidable part of using your phone to take images with a non-attached magnification device. Unlike an expensive camera with light meters and other tools, this setup will never quite produce a true to life image with no introduced imperfections.  

In terms of optics, the scopes performed well and were great in their own right; however, both the models I used were technically 1–2mm over the maximum specified eyepiece diameter. This was surprising as the mount seemed to fit fine (a little snug if anything), but also surprising as it begs the question as to why this adapter doesn’t fit the full range of Hawke products. This was not an issue with the binoculars as they have a much smaller ocular aperture. 

It is just as important to stress this wasn’t a test of the optics used but rather the adapter itself and, in that role, it performed very well. It held the phone securely and the rubberised touch points prevented slippage, keeping both the scope and phone lenses aligned. But, as stated before, this was a bit of a fiddly procedure.  

I do think that this adapter helps to bridge the gap between the more professional nature photography market and the more casual enthusiast who wishes to go and get some decent photos of what’s living in the area around them, and it will help to extend the reach of the average person’s smartphone camera by quite a distance. The speed of setup and lack of any frills really helps to make this adapter a portable, reliable workhorse or a spur of the moment image capturing tool. If you’re looking for an inexpensive bit of kit to add to your usual birding/hiking/survey gear alongside your pick of optics, this is the adapter for you.  

The Hawke Digi-Scope Smart Phone Adapter is available at www.nhbs.com/digi-scope

Author interview with Neil Middleton and Stuart Newson: Sound Identification of Terrestrial Mammals of Britain and Ireland

This groundbreaking book provides the reader with a unique and practical guide to collecting and using acoustic survey data to identify terrestrial mammals. Covering 42 species that can be found in Britain and Ireland, the text includes guidance on survey methods, analysis of sound recordings and details of appropriate software. As well as containing specific spectrogram examples for each species, the book allows the reader access to a downloadable sound library containing more than 250 recordings.

Neil Middleton is a licensed bat worker and trainer and is the owner of BatAbility Courses & Tuition, an organisation that delivers ecology-related skills development to customers throughout the UK and beyond. He has studied bats for over 25 years, with a particular focus on their acoustic behaviour (echolocation and social calls) and is the author of Social Calls of the Bats of Britain and Ireland, Is That a Bat?, and The Effective Ecologist.

Stuart Newson is a Senior Research Ecologist at the British Trust for Ornithology (BTO), where he is involved in survey design and data analysis from national citizen-science surveys. Stuart’s work on bioacoustics has included creating tools to identify European bats, bush-crickets and small mammal species from their ‘calls’. This resulted in the BTO Acoustic Pipeline, which integrates online tools for coordinating fieldworkers, processing recordings, and returning feedback.

Neil and Stuart recently took some time out of their busy schedules to answer some of our questions about their most recent book. In this Q&A we discuss the challenges involved in acoustic monitoring of mammals, the author’s hopes for the future of this area of study, and much more.

You each have a passion for acoustic monitoring – how did you come to be working together on this project?

Before we first met, Stuart was becoming interested in what else is recorded as ‘by-catch’ when you leave out a static bat detector to record bats. He had previously become interested in the sound identification of bush-crickets which are commonly recorded during bat surveys in southern Britain, and thanks to work that Neil was involved with (e.g. the first edition of the book The Social Calls of the Bats of Britain & Ireland), Stuart was becoming increasingly interested in bat social calls. At this time, he realised that small mammals are also quite commonly recorded as ‘by-catch’ during bat surveys, and was starting to appreciate that unless you had a good understanding of bat echolocation and social calls, there was scope for mis-identifying small mammals calls as being produced by bats.

When Neil started working on the book, Is That a Bat? A Guide to Non-Bat Sounds Encountered During Bat Surveys (ITAB), Stuart had already made available some online resources to help bat workers identify bush-crickets, which were able to feed into Neil’s book, and he also had some first recordings of some small mammal recordings that he was able to contribute to ITAB, which were very useful additions to the recordings that Neil had been gathering independently.

At about the same time, Stuart had met Huma Pearce, the third author on this book, and had started to work with her on an ‘edge-of-desk’ project to try and collect sound recordings for every species of small mammal in the UK. The aim was to try and collect many hundreds (ideally thousands) of sound recordings of every small mammal species in Britain and Ireland, which we wanted to build into bat classifiers to be able to assist with automatically identifying small mammals (as well as bush-crickets), when these are recorded as by-catch during bat surveys.

Working with Huma, and then Neil, to collect recordings for small mammals to feed into ITAB, and for Stuart to feed into his classifiers, we were now collecting a lot of recordings of small mammal species. After the publication of ITAB, we had learnt a lot more between us, so we wrote a more detailed guide to the sound identification of small mammals in Britain and Ireland, which was published in British Wildlife. After being approached by Pelagic Publishing, Neil was asked if he could author a book covering all terrestrial mammals in our part of the world. This was a much wider group than the one we had worked on up until that point. Neil agreed to the book idea, but only on the basis that Stuart and Huma would be involved as well. Thankfully both Stuart and Huma were ‘up for it’ and between us we managed to produce the book. I think we would all agree that if any one of us had not been involved, the job would’ve been considerably harder and taken much longer.

There currently exists a huge sound library of vocalisations of bats and cetaceans and their use in monitoring these species is now mainstream. Why do you think that this approach has not, so far, been used for other mammals such as those covered in your book?

We think that the main reason that so little has been done on the sound identification of terrestrial mammals (other than bats), is that for small mammals the call rate is quite low compared with other groups such as bats, and because the vocalisations can look like bat calls. I think until our various pieces of work, they have been largely overlooked. Until relatively recently, bat social calls had also been largely ignored by many bat workers, so there were few possibilities for noticing or identifying small mammal calls via that group. For audible mammal species, such as deer, there are alternative survey methods, such as visual surveys, and combined with this the call rate is again quite low, so without tools to help find these calls within large acoustic datasets it has been challenging to find and identify vocalisations by these species. In addition, before this book there was no resource or reference that people could use to help support the sound identification of audible mammals across the full range of species.

Added to this, we feel that the subject is difficult for many people in the non-bat mammal world to engage with and/or know where to start. Hopefully this book will open people’s eyes (and ears!) to the subject, thus meaning that more people will pay more attention to acoustic identification of these species, which will also mean that, overall, our rate of learning as a community will increase substantially as we begin to find out even more about the subject, including of course things that we didn’t appreciate at time of writing.

As well as providing the information and data required for species identification, do you think that acoustic data have the potential to tell us more about species behaviour, social interactions and population dynamics?

We think that there is huge potential for acoustic data to tell us much more about species behaviour, social interactions and population dynamics. As explored in the book, for some species we are able to relate particular call types to behaviour or status, but we still have a lot to learn for many of the species that are included in the book, in order to be able to understand in what situations particular calls are produced. By writing this book, we hope that this will inspire others to build on our work, and to accelerate an improvement in knowledge.

Which of the British terrestrial mammal species have you found the most challenging to study and why?

It is difficult to give a single answer to this one, but despite each of us having separate thoughts we would all agree on the following.

It was extremely difficult to collect or find existing sound recordings of rabbits and hares, because the call rate is extremely low. Huma (assisted by others) put lots of effort into rabbits, but sadly the results were zero. Separately Stuart tried to collect recordings of moles, by sinking microphones into the ground along mole tunnels, but he had no luck despite several weeks of effort.

Stuart would like to do more work on the sound identification of mustelids, which we feel we do not understand as much as we would like. We would all like to continue with more work on the small mammals, although we would each have different priorities in that respect. Shrews are of particular interest to us all, and Stuart in particular would definitely like to try and collect more sound recordings of Water Shrews.

Researchers have previously observed regional differences in the vocalisations of small birds recorded in various locations around Britain. Did you notice any geographic variations in the sounds produced by the mammal species you studied?

Personally, we haven’t seen much, if any, evidence of geographic variation in the recordings that we have looked at, but there could very well be regional differences. For some species it can be shown that differences occur at the individual level. This being the case, you could perhaps expect to see differences between social groups and, as such, regional and national differences too. At this point in time the amount of data we have is too small and hasn’t been collected with this in mind, and therefore we haven’t gone looking for an answer to this question ourselves.

There are currently several citizen science projects around the UK that the public can submit sightings to (such as those organised by the Mammal Society or apps such as iRecord). Is there currently anywhere that people can submit records resulting from acoustic data? Or somewhere they can submit their recordings in the hopes of building a library of sound files for each species as there is for bats?

Not that we are aware of, in the style that you have suggested by your question. However, if someone has heard (not seen) a species and they are happy that it is a diagnostic record for that species in a particular area, we would see no reason why a citizen science project would not accept the ‘sound’ as a valid record of the species being present at that location at that point in time. The key to this, however, is being confident that what was heard couldn’t be a similar noise made by something completely different – so we urge caution. It should also be remembered that in some cases sound identification may actually be more reliable than a visual record of a distant mammal, or a small mammal irrespective of how close it may be to the observer.

In a slightly different direction to your question, Stuart is best placed to talk about the use of such calls in building classifiers. His main interest in mammals has been to build a large sound library of known species recordings that can be used to build classifiers that can help identify the calls of different species automatically within recordings, with the book being secondary or a by-product of this. He believes that having such tools is essential for helping to find the calls of terrestrial mammals in large acoustic datasets, particularly for species where the call rate is low. The sound identification of all species of small mammals included in the book has been built into the ‘bat’ classifiers that comprise the BTO Acoustic Pipeline. The Acoustic Pipeline also includes specific classifiers for some audible species, including the Edible Dormouse. To the best of Stuart’s knowledge this is the first attempt from anywhere in the world to build classifiers for the sound identification of a complete assemblage of small mammals.

What are the next steps required to progress this research and what are your hopes for the future of this field of study?

There is still a lot to learn about the sound identification of mammals in Britain and Ireland, but there are some species groups on which we know we have done much less work and have less understanding than others. In particular, we think that acoustics could be useful for detecting the presence of mustelids (as we have already demonstrated for mice, rats, voles, shrews and dormice), but we would need to try and collect many hundreds (ideally thousands) of known species recordings, to be able to understand the full range of calls that a species can produce. This information could then also be used to create automated classifiers, thus enabling the possibility of efficient detection of species in this group from within large datasets.

As a longer-term ambition, Stuart is keen to work further on the wider sound identification of European mammals, and to extend the geographic and taxonomic scope of the BTO Acoustic Pipeline. Currently, he is able to identify small mammals in bat recordings from elsewhere in Europe at least to genus, by including similar closely related species from the UK in regional classifiers for other parts of Europe. However, he needs more targeted recording of known species to be carried out in order to be able to assign these identifications to species, and to be able to build classifiers that support the sound identification of mammals more widely across Europe.

Our hopes are that this book inspires others in Europe (and further afield) to work on the sound identification of mammals, and more widely to see the opportunities that understanding acoustics can offer.

Sound Identification of Terrestrial Mammals of Britain & Ireland is published by Pelagic Publishing and is available at nhbs.com.

Author interview with Neville Davies: The Eurasian Hoopoe

Once resident in the UK, the Eurasian Hoopoe is the most widespread of its genus and is much admired for its striking appearance and entertaining character. Containing a huge amount of astonishing and fascinating facts about these magnificent birds, this book is packed with everything you need to know about this species. It is a captivating read for beginner, intermediate or expert alike, and for anyone who has an interest in birds and the natural world.

Neville Davies is an author, wildlife columnist, book reviewer, leader of nature walks and courses, and private bird guide specialising in the birdlife of Mallorca. His previous book, Birds of Mallorca provides readers with an essential guide to the best birding sites and 340 bird species that can be found on the Balearic island of Mallorca.

The Eurasian Hoopoe, which is due for publication at the end of November, provides an in-depth look at one of the species that has fascinated Neville since childhood.

We recently chatted with him about his inspiration behind the book, his hopes for the future of this incredible species, and his plans for further writing.

What inspired you to write a book about the Eurasian Hoopoe?

As a child I would often look through the bird books I had at the time, and one species that stood out for me from the hundreds of others was the European Hoopoe (hereafter referred to as the Hoopoe). There was something magical about this strange looking bird, with its ‘punk rocker’ plume of head feathers and black and white wing markings. It looked like an iconic bird and when I read it was found on the continent and other far-away places (which I assumed I would probably never get to visit), this made it even more special – the Hoopoe would forever be out of my grasp, or so I thought. Every time I acquired a new bird book, I always found myself going straight to the page on the Hoopoe. By 1990 I had decided that I was going to visit Mallorca specifically to find them; an early guidebook I had bought listed the Hoopoe as a common resident breeder, so I felt I had a good chance of finding one.

But by the third day of my first visit to Mallorca, there was still no sign of a Hoopoe. I was beginning to think that I was never going to see one and disappointment and anxiety started to creep in. But later that third day, I saw my first ever one flying low across a field and out of sight behind a farm building. I punched the air in sheer delight, I had finally seen one for real and my excitement was overwhelming. I went in search of it and spotted it along with a second bird. And what I had thought when looking through the guidebooks as a child was right, the Hoopoe is truly a magical bird and they look as characteristic in real life as in the books – the plume of punk rocker head feathers did not disappoint.

I already owned several bird books by other authors specifically on a single bird species, and this got me thinking, why not write about the Hoopoe? Not only is the Hoopoe my favourite species in the bird world, but surely there must be enough information available to make an interesting book. I was pleased to find research papers written on the Hoopoe from all over the world – there was certainly enough information for a book. The more I looked the more I found, and I learned so much about the Hoopoe that I didn’t already know. There were also some great photographs in these papers, and I started to contact several of the authors to ask if I could use their images and some of their findings. Thankfully, they were very keen to support me, so along with my own images and information I was able to provide more in-depth information, especially around breeding and prey items, and excellent photographs.

Could you tell us about the status of the Hoopoe and the kinds of threats they face?

The European breeding population is large (890,000 pairs), and the Hoopoe is doing well across the rest of its range in Asia and Africa; it is regarded as a species of Least Concern due to its widespread population. This does not mean we should be complacent, however, as the Hoopoe still faces threats, especially from hunting. The Hoopoe is regarded as a trophy species, and their distinctive undulating flight makes it an easy target for hunters and poachers. In Lebanon, for example, they are kept in cages to be sold in local markets and are often in a dreadful condition and poorly fed. It is sickening and distressing to know that a bird as majestic as the Hoopoe (or any bird for that matter) lives out the rest of its life in a cage, unable to enjoy the freedom of flight. One organisation that is doing sterling work to protect not just the Hoopoe but all birds is the Committee Against Bird Slaughter. They conduct annual bird protection operations in Spain, Italy, Malta, Cyprus and Lebanon.

Hoopoes face other forms of predation in the wild too. Both the Eleanora’s Falcon and Sooty Falcon will target Hoopoes as they migrate across open areas of water, where they are tired and easy prey. At their nest sites they can fall prey to several predators, with the seven main culprits being the Western Whip Snake, European Asp, Eurasian Magpie, Little Owl, Red Fox, Black Rat and domestic Cats.

You mention that Hoopoes were once resident in the UK but are now passing migrants. Could the Hoopoe make a long-term return?

Hoopoes were once a resident species in the UK but are now confined to being a scarce but regular passage migrant to Britain, with most sightings occurring in the spring and autumn. On average, sightings range between 100 and 150 individuals with the bulk of UK records coming from the south coast counties, although there are records from every county in the UK. The Hoopoe has bred here sporadically since the early 19th century with at least 1–4 instances recorded in each decade since the 1830s (again mostly from the southern counties). More modern records have appeared in 1971, 1976, 1977 and 1996. In 1977, pairs fledged young in Avon, Somerset, Surrey and Sussex, which is quite remarkable. The 1996 occurrence came from the Montgomeryshire area. On average, singing males are recorded every five years or so (males sing to attract females). Could they make a long-term return to the UK? Why not. In fact, recent news from Leicestershire reports that a pair of Hoopoes have successfully bred and raised three young and been seen frequenting a private garden.

Favourable conditions can bring in arrivals in large numbers, in some years this can be as early as late February. Hoopoes can turn up anywhere, with Ireland having at least 15 records; although, the further north one goes the scarcer the records become. Visiting the south coast during spring does not guarantee a Hoopoe sighting but it is certainly when and where there is the best chance of finding one. In southern England, favoured localities include the Isles of Scilly; Porthgwarra; Land’s End and the Lizard, Cornwall; Start Point and Prawle Point, Devon; Portland, the Needles, Isle of Wight; Selsey Bill, West Sussex; Dungeness and Sandwich Bay, Kent. Favourable likely locations on the east coast include Blakeney Point in Norfolk and Spurn East in Yorkshire. In the autumn, east coast locations tend to fair better sightings wise, with a scatter of drift and reverse migrants.

What conditions would be necessary for such a return?

In spring, when high pressure leads to fine settled weather over Western Europe, some migrants returning to the Mediterranean region fly right over their intended target and end up in Britain. This is known as overshooting. Across their range, Hoopoes can be seen in a variety of habitats, including gardens, parks, towns, villages, marsh edges, open fields with vegetation and ploughed fields. They can also be found in groves of olives, almonds, grapes and other fruits where the lines of trees provide shade, allowing them to feed during the hottest parts of the day, and the diversity of vegetation and rich soil also support a good variety of insect prey, including the Mole Cricket, their favoured prey.

If Hoopoes were to return to the UK permanently, they would need suitable breeding habitats, such as open areas of short grass and soft soil where they can probe for insect prey coupled with areas of mature trees in which they can build their nests in natural holes (they do not excavate holes). Old buildings, stone walls, cavities, cliffs, among boulders, drainpipes, wells, roof spaces and nest boxes are also used as nest sites. Although they prefer Mole Crickets, in the UK other species of cricket, grasshoppers, millipedes, centipedes, spiders, woodlice, snails, slugs, ants, and occasionally even lizards and frogs would form a part of their diet.

What would you recommend to someone looking to watch Hoopoes in the wild?

To maximise your chances of seeing Hoopoes in good numbers and to hear their distinctive calls, I recommend visiting somewhere where they are a common resident, such as in Spain or the Balearic Islands. In Mallorca for example, one site I visit is called Son Real where it is possible to see up to a dozen in a single visit. Visit the type of habitat they like to frequent, especially olive groves and orchards and open fields with a good scattering of nearby trees. Scan the ground as this is where they will be feeding, but also look to the roof tops of derelict buildings or outbuildings or the lower branches of trees where they like to perch. If you are quiet and do not move too much, they will allow you to approach them without being disturbed. Also, listen out for their ‘oop-oop-oop’ call which sounds like their name. Be patient, you will see one. If you visit other locations there are sub-species too, such as the African Hoopoe and Madagascar Hoopoe.

Do you have any plans for any further books you can tell us about?

I am hoping this book is a success, as I have thought about writing another book about the European Bee-eater. I have already written a bird guide called Birds of Mallorca (available from NHBS) – it will be no surprise that the cover photo features a Hoopoe. I have another book which I have written called Not Quite Living the Dream, which is based on my attempts to reside in Mallorca and covers everything from wellbeing to birds, but I am hoping a sponsor comes on board to support me financially with that one.

 

The Eurasian Hoopoe: Everything You Could Want to Know About This Iconic Bird is privately published by Neville Davies and available from nhbs.com.

This week in biodiversity news – 13th November 2023

Extinction Risk

First images of a lost echidna species prove that it is not extinct. An expedition to the sacred Cyclops Mountains in Indonesia uncovered evidence of Attenborough’s Long-beaked Echidna. Echidnas are ancient egg-laying mammals thought to have emerged 200 million years ago when dinosaurs still roamed the earth. Until now, the only evidence for this particular species of echidna, named after Sir David Attenborough, was a museum specimen. Scientists hope that the discovery of living echidnas will help make the case for conservation efforts in the Cyclops Mountains. In addition to the echidna, new species of insects and frogs were discovered alongside healthy populations of birds of paradise and tree kangaroos.

Echidna by Rod Waddington via Flickr. (Species differs from that mentioned in the above text).

Fewer than half of Bornean Sun Bears survive after release due to habitat loss and poaching, according to a recent study. Sun Bears are a keystone species in the jungles of South-East Asia, helping to sustain healthy forest ecosystems; however, fewer than 10,000 Sun Bears are thought to remain in the wild due to pressures from deforestation, habitat degradation and poaching. The Bornean Sun Bear Conservation Centre (BSBCC) looks after Sun Bears rescued from captivity and releases them back into the wild. A recent study has shown that many released Sun Bears die due to the dangers they encounter in the wild, including poaching, territorial disputes and starvation. A lack of familiarity with their new surroundings may also contribute to this high death toll despite the released bears being skilled climbers and foragers.

Malayan Sun Bear by cuatrok77 via Flickr.
Conservation

An ambitious project in the Fens seeks to reclaim thousands of acres for nature. The Great Fen Project, organised by Wildlife Trust conservationists, aims to purchase 9,000 acres of farmland around two Fenland nature reserves to allow water to return to the land. This will support the formation of water meadows, streams and pools which will encourage wetland species such as Bittern and Marsh Harrier. By rewetting fields, it also seeks to preserve peat and reduce carbon emissions. With a projected price tag of around £30 million, the project will be one of the most ambitious restoration projects in all of Europe.

Wicken Fen by Alex Brown via Flickr.

Svalbard is letting nature take back one of its massive coal mines. The Svea mine in Svalbard, Norway, which produced 34 million metric tonnes of coal over its lifetime, is undergoing a significant natural restoration project. The restoration effort, costing approximately 1.6 billion Norwegian kroner (€1.35 million), aims to return the site to its natural state, allowing nature to reclaim the land. This move is part of Norway’s commitment to preserving the wilderness of Svalbard, as the region transitions away from the fossil fuel industry, closing coal mines and shifting towards tourism and scientific research.

Climate Crisis

Surges in jellyfish numbers in UK waters are an indication of warming oceans, according to the Marine Conservation Society. The number of jellyfish seen on UK beaches has increased by 32% in the past year. Warm water jellyfish such as the Crystal Jellyfish have been spotted following global ocean temperatures reaching a record high in August and marine heatwaves in June which caused UK sea temperatures to rise by 3–4°C. Experts have said that more research will be needed to determine the exact cause of the jellyfish blooms this year.

Jellyfish on Cefn Sidan Sands by Reading Tom via Flickr.

Global temperatures will reach the 1.5°C threshold this decade, according to a new report. In 2015, countries agreed to take measures to hold global temperatures to 1.5°C above pre-industrial levels as part of the Paris Climate Agreement. New research by a team of scientists from Columbia University and NASA suggests that this goal is already out of reach, which may raise alarm bells at the coming COP28 climate talks. Other estimates suggest that the threshold will be breached in the 2030s.

Education and awareness

The RSPB is to give under 25s free access to its nature reserves in a bid to increase youth engagement with nature. The charity is set to roll out the two-year pilot program this month. The programme seeks to address what research has shown to be a dip in nature connectedness in teenage years. Similar worries prompted the government to introduce a new GCSE in natural history, and other nature charities are seeking to focus on outreach to the younger generations.

RSPB Fowlmere by Airwolfhound via Flickr.
Discoveries

Chimpanzees in Ivory Coast have been observed using military-like tactics to gain an advantage over rivals, a study has revealed. Chimps were observed seeking high ground for reconnaissance missions and making strategic decisions based on the size and proximity of rival groups. This behaviour, similar to the concept of “occupying the high ground” in warfare, may have deep evolutionary roots, according to researchers at the University of Cambridge. 20,000 hours of recordings revealed that chimps would climb hills at the edge of their territories, rest quietly at the top to listen for nearby rivals, and then decide whether to advance or retreat. While many animals take to higher ground to keep watch, chimp tactics are more sophisticated, anticipating where conflict may occur, assessing risk, and making collective decisions on how to proceed.

Chimpanzee by Nigel Hoult via Flickr.
Diplomacy

An agreement has been reached for a loss and damage fund in the run-up to COP28. The fund, which aims to help countries cope with the irreversible effects of climate change, had been established last year at COP27, but negotiations had come to a standstill over which organisation would administer the fund. However, an agreement was reached in Abu Dhabi over the weekend with recommendations to be considered at COP28 which starts in late November in Dubai.

Book review: The Rise and Reign of the Mammals

***** Epic in scope and majestic in execution
Leon Vlieger, NHBS Catalogue Editor

Imagine being a successful dinosaur palaeontologist and landing a professorship before you are 40, authoring a leading dinosaur textbook and a New York Times bestseller on dinosaurs. Imagine achieving all that and then saying: “You know what really floats my boat? Mammals.” After the runaway success of his 2018 book The Rise and Fall of the Dinosaurs, palaeontologist Stephen Brusatte shifted his attention and now presents you with the follow-up, The Rise and Reign of the Mammals. Taking in the full sweep of mammal evolution from the late Carboniferous to today, this book is as epic in scope as it is majestic in execution.

Mammals shared our planet with the dinosaurs throughout their long reign, from the initial split of our amniote common ancestor into synapsids (us) and diapsids (them), to their extinction at the end of the Cretaceous. Over the course of some 100 million years, a parade of lineages evolved—archaic mammals all—piecemeal developing the traits we recognise as mammalian today: pelycosaurs, therapsids, cynodonts, mammaliaformes, docodonts and gliding haramiyidans, multituberculates, and therians who gave rise to today’s placentals, marsupials, and monotremes. However, the above must not be mistaken for a linear march of progress. “[M]ammals were a still unrealised concept, which evolution had yet to assemble” (p. 20). Simultaneously, it does not behove us to call these now-extinct groups evolutionary dead ends. “In their time and place, these mammals were anything but obsolete” (p. 88).

With the extinction of the dinosaurs, the rise of mammals turned into a reign. Isolated on various land masses after the supercontinent Pangaea had fragmented, they were poised for a slow-motion taxonomic starburst that would play out over the next 66 million years. In the northern hemisphere, placental mammals replaced multituberculates and metatherians and rapidly evolved into primates and the odd- and even-toed ungulates. The latter two evolved giants: brontotheres, chalicotheres, and cetaceans.

Brusatte’s strength is to bring to life the above flurry of names. What kind of creatures were they? And how can we deduce this from fossil evidence? Somewhere between chapters 6 and 7, I became awestruck by his narrative as the enormity of the mammalian evolutionary trajectory started to come into full view: bats, elephants, South American native ungulates (origins: uncertain), metatherians migrating to Australia and spawning a spectacular marsupial radiation, grazers diversified as grasses went global, and somewhere at the end, hominins evolving and repeatedly spilling out of Africa, contributing significantly to recent megafauna extinction. What a wild ride!

The macroevolutionary story is fascinating in itself, yet Brusatte makes it even better with some interesting observations of his own. We usually think of the dinosaurs as dominating the mammals, but, he suggests, this went two ways: “While it is true that dinosaurs kept mammals from getting big, mammals did the opposite, which was equally impressive: they kept dinosaurs from becoming small” (p. 95). Furthermore, DNA studies suggest that many modern mammal lineages originated back in the Cretaceous. But where are the fossils? Could some of the poorly understood archaic placentals such as condylarchs, taeniodonts, and pantodonts be the missing fossils that we have not yet been able to link to modern groups because of the lack of signature anatomical features? Excitingly, Brusatte is part of a research consortium that is building a master family tree based on both anatomy and DNA.

As in his last book, Brusatte excels at explaining complex research methods and scientific concepts. One example is Tom Kemp’s concept of correlated progression. Several times during early mammal evolution, a whole suite of anatomical, behavioural, and functional traits were changing together, making it hard to unravel what was driving what. For instance when cynodonts shrunk in size and changed their growth, metabolism, diet, and feeding styles. Then there is the revision of the mammal family tree based on DNA sequencing. The classic tree, championed by zoologist George Gaylord Simpson in 1945, was based on anatomical features. By the early 2000s, DNA-based genealogies suggested that many supposed relationships were actually cases of convergent evolution, resulting in a new classification that reflected geographical patterns rather than anatomy. The new groupings came with some tongue-twisting names: Afrotheria, Xenarthra, Laurasiatheria, and Eurarchontoglires. A final example is tooth morphology, an important diagnostic trait in this story.

What helps with these explanations are some excellent illustrations. B/w photos show amazing fossils, Todd Marshall contributes both decorative chapter headings and explanatory artwork, and Brusatte’s former student Sarah Shelley adds b/w diagrams, illustrating for instance the remarkable changes in jaw bones and how some of these were repurposed to become our inner ear bones! Woven throughout are stories of the people behind the research. Brusatte introduces both young scientists and many past scientists that are not widely known.

In what is surely a hallmark of his love and enthusiasm for the field, Brusatte’s bibliography has again been written as a narrative. It is like a chatty literature review in which he recommends books and papers, indicates where literature has become outdated, adds more technical details or clarifications, discusses where there is active debate and disagreement, and shortly touches on topics that he had to omit from the main narrative. Yes, this takes up more space than a regular reference section, and I am sure it is more time-consuming to write, but it is ever so useful. You could not wish for a better starting point if you wanted to read deeper into the technical literature.

Finally, you might be left wondering how this book compares to Elsa Panciroli’s Beasts Before Us which covered early mammal evolution up to the K–Pg extinction. There is overlap here in more than one way; Brusatte co-supervised her PhD project describing the docodont Borealestes from a Scottish fossil. I was therefore mildly surprised that he does not mention her book. There is some inevitable overlap as both books walk through the same groups, though Brusatte provides a fuller picture by covering mammal evolution up to today. Panciroli’s book stands out for its fantastic writing, though, so you cannot go wrong by reading them both.

The Rise and Reign of the Mammals is a more-than-worthy successor to The Rise and Fall of the Dinosaurs. Brusatte convincingly shows that the evolutionary story of mammals is just as fascinating—if not more so—as that of the dinosaurs.

Book review: What an Owl Knows

***** A hoot of a book
Leon Vlieger, NHBS Catalogue Editor

Owls are one of the most enigmatic groups of raptors, in part because there is so much we still do not understand about them compared to other birds. Nature writer Jennifer Ackerman previously wrote the critically acclaimed The Genius of Birds. In What an Owl Knows, she reveals the creature that hides under that puffy exterior, peeling back the feathers layer by layer to show our current scientific understanding of owls. She has interviewed scores of scientists and owl aficionados as part of her background research, making this as much a book about owls as about the people who study and love them. A captivating and in places touching science narrative, this book is a hoot from beginning to end.

Owls are everywhere in the human imagination and, Ackerman argues, have always been: “We evolved in their presence; lived for tens of thousands of years elbow to wing in the same woods, open lands, caves, and rock shelters; came into our own self-awareness surrounded by them; and wove them into our stories and art” (p. 235). For all that, their nocturnal lifestyle makes them hard to study and they have long been—and in many places still are—wrapped in superstition. Ackerman dedicates a chapter to such beliefs and the harms that frequently flow from them. Fortunately, the tide is turning. Thanks to the tireless efforts of a dedicated cadre of scientists, conservationists, and numerous volunteers, a far more fascinating creature emerges from the contradictory tangle of ideas that humans have held about owls.

A red thread that has been subtly woven through this book is the importance of understanding animals on their terms. Ed Yong’s An Immense World is one recent example of this welcome trend amongst science writers and Ackerman appropriately starts with a chapter on owl sensory biology. What is it like to be an owl? Though this question can never be fully answered, that should not stop us from trying our hardest. Vision and hearing are obviously important to owls but the book has plenty of surprises up its sleeve once you start digging into the details: from the magnificent facial disk that acts somewhat like a parabolic reflector to gather sound, a hearing system that does not seem to age, to the fact that owls can see ultraviolet light. At night. With rod rather than cone cells (like pretty much every other bird).

The same question motivates research on owl vocalisations as “a hoot is not just a hoot” (p. 81). Owls utter a profusion of yaps, squawks and warbles and Ackerman paints a lively portrait in words. Barn owls have “a raspy hiss that sounds like a fan belt going out on your car” (p. 82), while the tiny Flammulated Owl breaks the link between body size and vocal pitch, sounding like “a big bird trapped in a small body” (p. 82, quoting ornithologist Brian Linkhart). These sounds can reveal an awful lot about the individual owl and its relationship with other owls in the landscape. Ackerman criticises some of the research on owl intelligence. They cannot pass the string-pulling test, a common test in ethological research in which an animal has to pull on a rope to reel in food that is out of reach. The idea is that it tests an animal’s understanding of cause and effect. But is this a fair test or does it “point to the limitations of our definitions and measures of intelligence” (p. 261)?

The most intimate insights have come from rescued owls that can no longer be returned to the wild. Many researchers have ended up caring for an individual and becoming intimately familiar with them. Gail Buhl, a leading authority on training rehabilitated captive owls, here explains five important things that she has learned. One particularly poignant observation is that owls might appear calm and stoic around humans, but having paid close attention to their body language, Buhl concludes that “they’re experiencing the same stress as other raptors, but they’re internalising it” (p. 228). This has major consequences for how even well-intended trainers and rehabbers ought to behave around owls. “We need to treat them not as mini-humans in feathers, but as their own entity” (p. 231), Ackerman writes, before throwing in a beautiful quote from naturalist Henry Beston. In his words, wild animals “are not brethren, they are not underlings; they are other nations, caught with ourselves in the net of life and time” (pp. 231–232).

Following on directly from her last book on bird behaviour, there are fascinating chapters here on the behaviour of owls: their courtship and breeding, their parental behaviour, their roosting, and their migration. Yes, many owls are migratory and some species can cover surprising distances. Ackerman makes a fantastic case for the value of long-term monitoring programmes to establish reliable population estimates. This is vital data for conservation efforts and is often missing. And sometimes what we think we know is wrong, as in the case of the Snowy Owl. Where initial estimates put the global population at some 200,000 birds, satellite tracking has revealed that they are actually a single population moving around the whole Arctic Circle, resulting in duplicate counts. Revised estimates now put the figure at a mere 30,000 birds.

Ackerman relies on the input of numerous scientists and volunteers. As such, this is as much a book about the people who study owls. I was delighted to hear more from Jonathan Slaght (his book Owls of the Eastern Ice is magnificent). Other stories tug on the heartstrings and none more so than that of Marjon Savelsberg. A Dutch musician trained in baroque music, her dreams came crashing down when she was diagnosed with a heart condition that consigned her to a mobility scooter. When she stumbled on the website of the Dutch Little Owl Working Group, she quickly became one of their most active volunteers, revealing a skilled ear for analysing owl calls. Suddenly, she had a new career and a new group of appreciative ecologist colleagues: “[I] realised I was still a musician. All the skills that I learned, all the talent I have, I can still use, just in a different way” (p. 105). It is a powerful story of redemption-by-owl.

Ackerman carefully balances these two facets: the scientific insights that she has carefully distilled from research papers and interviews, and the personal stories of those who study and love owls. As a result, What an Owl Knows is compulsively readable and readily accessible for those who lack a scientific background in ornithology.

You might also be interested in reading our Q&A with Jennifer Ackerman in which we discuss owls’ reputation for wisdom, the incredible research that is shedding more light on their lives, and the mysteries that still remain.