Owl Pellet Dissection

Owl pellets contain all of the indigestible parts of the prey. Image by Gail Hampshire via Flickr.
What is an owl pellet?

Owls feed on a variety of prey; most commonly small mammals but also birds, frogs and other small animals. These prey items are consumed in their entirety and, while the flesh is digested by enzymes, the owl is unable to digest the harder parts of the body, including the teeth, bones, fur or feathers. These indigestible parts are regurgitated as a pellet. Unless they are very fresh, pellets are dry, light and odourless.

In this article we will look at where to find owl pellets and how to tell which species of owl they came from. We will also provide some tips on how to dissect a pellet, how to group the bones into types, and how to identify some of the main species of small mammal that you will find in pellets in the UK.

Where to find owl pellets

Owl pellets can frequently be found wherever owls nest or roost. Good places to search are at the base of tall trees within woodland areas, or in barns or outbuildings where owls are known to roost. Please be aware that you must not disturb breeding or roosting owls in order to collect pellets. Barn Owls in particular are protected in the UK by law under the Wildlife & Countryside Act 1981 and their breeding sites must not be disturbed under any circumstances.

If you don’t have any luck finding your own pellets or don’t have access to places where you might find them, there are several places online where you can order some. Reputable sources in the UK include the Barn Owl Trust and the Suffolk Owl Sanctuary.

What species of owl is my pellet from?

There are five resident species of owl in the UK: Barn Owl, Tawny Owl, Little Owl, Short-Eared Owl and Long-Eared Owl. All of these species produce pellets that are relatively easy to tell apart, particularly if you also know the habitat where they were found. Below is a brief guide to their main characteristics.

• Barn Owl: pellets usually measure 3-7cm in length and are rounded at both ends. They are fairly dark in colour and have a smooth surface.
• Tawny Owl: pellets measure 2-5cm in length and are narrow and bumpy, often having tapered ends. Greyish in colour and sometimes furry looking.
• Little Owl: pellets are fairly small measuring only 1.5-2cm in length. Long and narrow with a soft crumbly texture.
• Short-Eared Owl: pellets are fairly large, measuring 3-6cm in length. Narrow with one rounded end and one tapered end. They are grey and smooth and very lightweight.
• Long-Eared Owl: pellets measure around 2-4cm and are narrow and bumpy. Usually grey in colour.

The most common pellets you will find in the UK are from Barn Owls.

Barn Owl pellet with mounted needle and fine pointed forceps.
How to dissect an owl pellet

There isn’t much equipment you need to dissect an owl pellet, but a few items will make the job a bit easier:

• Mounted needle: this is useful for teasing out fur from around the bones, and moving around delicate specimens. A cocktail stick or needle pushed into a cork will also do the trick.
• Forceps/tweezers: helpful for picking up bones and particularly for removing fur from inside skulls. Forceps with a fine point are best.
• Magnifying glass/hand lens: a small magnifier will allow you to get a closer look at the bones that you find. Jaw bones in particular are very useful for identifying the species and a magnifier will help you get a better look at the arrangement and structure of the teeth.
• White paper/card and glue: it can be helpful to arrange your bones by type onto a sheet of white paper which you can then write on when you have decided what they are and who they belong to. If you would like to make a permanent ID aid you can also glue them onto a piece of card and add permanent labels.

How to identify the contents of an owl pellet

The first thing you will need to do is to tease apart the pellet and separate the bones from the fur and feathers that are holding it all together. To begin with it is easiest to gently break the pellet into several smaller sections then work on each of these in turn. Use your fingers as well as the forceps to carefully tease apart each section, removing any bones and placing them to one side for identification. If your pellet is very hard and dry, try soaking it in water first to soften it.

Once you have all of the bones from your owl pellet, try to group them into types on your sheet of paper. The most common bones you will find are the following:

  • Skulls: for mammals, this consists of the top part of the skull and upper jaw, along with the lower jaw, although this is likely to become detached once you have cleaned all of the fur and other material from inside. For bird species this will include the upper and lower parts of the beak.
  • Back legs: includes the thigh bone (femur) and the lower leg bones (fibula and tibia)
  • Front legs (arms or wings): includes both upper (humerus) and lower (radius and ulna) bones
  • Hip bones
  • Shoulder blades (scapula)
  • Back bones (vertebrae)
  • Ribs

The image below illustrates typical examples of each type of bone. You can also download a useful bone identification sheet from the Suffolk Owl Sanctuary website.

 

The most useful part of the skeleton for identification is the skull and jaws or beak. Bird skulls will obviously be very distinct from those of mammals due to the presence of the beak, so these can immediately be separated out. For the remaining mammal skulls, however, we will need to take a closer look at their lower jaw bones and teeth.

In the UK the most common small mammals you will find in owl pellets are voles, mice and shrews. It is very easy to distinguish which of the lower jaws belong to shrews as they have a continuous line of teeth from the front to the back of the jaw. This is because shrews are insectivores and chew their food, much the same as we do. Voles and mice, however, both gnaw their food, and have a big gap between the long front tooth and the back teeth.

To tell the difference between voles and shrews, we need to take a closer look at their back teeth. Voles have teeth with distinctive grooves down the sides.  In those of a field vole, the grooves run all the way down the side of the tooth. There is also no obvious root. Bank voles have grooves which only run part-way down the side of the tooth and they have two obvious roots, similar to those of a human tooth. The back tooth from a mouse jaw is much smaller when compared to a vole and its structure is much more similar to that of a human tooth. It also has two roots. This sheet from the Barn Owl Trust has a great illustration of the various small mammal lower jaws with size guidelines to help with identification.

Hopefully this article has been a useful introduction to owl pellet dissection and the identification of some of the most common prey species contained within them. If you want more help with identifying all of the bones in your pellet down to species level, the guides listed below are invaluable. Once you have categorised all of the bones you can attach them to a piece of card with permanent labels or arrange them to create a complete skeleton of each species.

Finally, don’t forget to wash your hands well when you have finished your dissection. Any pellet remains can be safely composted.

Further reading

Guide to British Owls and Owl Pellets

This fold-out chart includes colour paintings of the five species of owl permanently resident in the British Isles, shown both perched and at rest. Also included are illustrations and written descriptions of the different pellets that may be found, and a systematic identification key to their contents, including complete skulls, jaws, teeth and other recognisable bones and animal parts.

 

The Analysis of Owl Pellets

This booklet will not only enable you to identify what you find in the pellets of British owls, but also shows how the data may be usefully presented and how to estimate the actual weight of food the birds have eaten.

 

This Week in Biodiversity News – 15th June 2022

Climate change

New Zealand farmers have suggested that the government should impose a levy on agricultural gas emissions to encourage the reduction of methane and nitrous oxide emissions. The government had legislated that farmers must develop an emissions pricing system or agriculture would automatically enter the country’s emissions trading scheme. Grassroots farms have been protesting in recent years against the introduction of environmental regulations, but agriculture currently generates over half of New Zealand’s industrial and household emissions. The sector has been facing significant political pressures over this disproportionate contribution to climate change.

Climate change is impacting whale habitat use in the Gulf of Maine. Warming waters has caused right and humpback whales to shift their use of Cape Cod Bay over the last 20 years. Using aerial surveys conducted from 1998 to 2018, the research team analysed environmental data to study changes in whale habitat use within and across years. The peak use of Cape Cod Bay by these species has sifted almost three weeks later, related to the arrival of spring, which has been changing due to climate change. Right whales may be using Cape Cod Bay for longer periods because climate change has reduced the amount of food available in other Gulf of Maine habitats.

Conservation

For the first time in 30 years, Zoo Atlanta has successfully hatched a Critically Endangered Bog Turtle. This species, Glyptemys muhlenbergii, is the smallest turtle in North America and has only been documented in 10 states in the US. The zoo’s captive breeding program includes one male and two females, which the zoo reports are still young to have reproduced. 

Young bog turtle by Gary Peeples/USFWS via Flickr

Research

A new study has estimated that 44% of Earth’s land is needed to stop the biodiversity crisis. Environmentalists have been lobbying governments to commit to protecting 30% of Earth’s land, but this may not be enough. A computer-generated global map has been created, showing the most efficiently marked amount of the typically needed territory of 35,561 species. This adds up to around 64 million square kilometres, which would require various levels of conservation management, from a strict ban on most human activities to regulations on sustainable development.

Scientists have used food puzzles to study how otters learn from each other. Using a combination of puzzle boxes and unfamiliar foods, the team observed that Asian short-clawed otters watched their companions and copied others when they sampled the unfamiliar food. This study aimed to understand how captive release otters would cope with unfamiliar food in their natural environments once they were released. The results suggested that if one otter was given pre-release training, it could pass some of that information onto other otters.

Asian short-clawed otter by adam w via Flickr

According to a new study, tropical birds may be more colourful than their temperate peers due to the difference in energy availability. Tropical areas have more food year-round and more constant temperatures, potentially allowing tropical birds to evolve more visual signals. Another explication may be diet, as fruits rich in organic pigments, which tend to accumulate in the feathers of birds that consume them, are more abundant in the tropics.

New discoveries

The Critically Endangered adult pine hoverfly (Blera fallax) has been seen in the wild in Britain for the first time in almost a decade. In October 2021 and March 2022, larvae were released at RSPB Abernathy and Forestry and Land Scotland Glenmore, bred as part of the Royal Zoological Society of Scotland’s conservation breeding programme. The pine hoverfly is an important part of forest ecosystems due to its role in both pollination and waste recycling.

Pine hoverfly by Frank Vassen via Flickr

A scientist from Newcastle University has rediscovered an ‘extinct’ giant tortoise on Fernandina, one of the Galápagos Islands. Through genetic testing of a female tortoise found in 2019 and a previous specimen found in 1906, the researchers found that the two were genetically linked and distinct from all other living species of Galápagos giant tortoises. Other expeditions to the island have found evidence of at least two or three more tortoises, which are hoped to be of the same species.

Microplastics

Scientists have found microplastics in freshly fallen Antarctic snow for the first time after collecting samples from 19 sites in Antarctica. An average of 29 particles per litre of melted snow was found, consisting of 13 different types of plastics. The most common, polyethylene terephthalate (PET), was found in 79% of samples. This plastic is primarily used in drinks bottles and clothing. While researchers suggested that the most likely source for these airborne microplastics is local scientific research stations, modelling has shown that their origin could be up to 6,000km away.

Researchers in the Canary Islands have discovered a new form of marine pollution that they have termed plastitar, a mix of tar and microplastics. This formation of two contaminants is an unassessed threat to coastal environments and could be leaking toxic chemicals, potentially proving deadly for organisms such as algae. There is concern that this formation may be blocking and inhibiting the development of the ecosystem.

Policy

No-anchor zone in Studland Bay has been extended to save seagrass habitats. The scheme, set up in December, was introduced to stop anchors dropping and damaging the seagrass meadows. However, there is concern that this voluntary scheme is not being advertised enough to sailors and that there are not enough eco-moorings, an alternative to conventional anchors that do not scour the seagrass. 

In The Field: Browning Spec Ops Elite HP5 & Browning Recon Force Elite HP5

The Browning Spec Ops Elite HP5 and Recon Force Elite HP5 are the 2022 additions to Browning’s highly regarded Spec Ops and Recon Force series, featuring Browning’s Radiant 5 illumination technology. We tested these cameras by setting them up in various habitats across Devon and Sweden over several days and nights in May.

Browning Recon Force Elite HP5

Both trail cameras take 24MP images and record in Full HD (1920 x 1080p), with an adjustable trigger speed of between 0.1 and 0.7 seconds, and a recovery time of 0.5 seconds between images. The footage is recorded in colour during the day, and in black and white during the night or in low-light conditions using the infrared LEDs. As with most high-spec Browning trail cameras, the 5cm colour screen helps when positioning the camera, as you can view the area that will be captured in images and videos, and watch footage from the SD card live in the field without the use of an additional device.

Browning Spec Ops Elite HP5

The display menu is simple to use and the settings are easy to navigate through, enabling you to alter the settings depending on the needs of different target species. The programmable stop/start timer allows you to designate a window of time when the camera will trigger and target the activity periods to match certain species. The adjustable infrared flash can be set to automatically adjust for perfect nighttime photos or be set to Fast Motion (for fast target species), Long Range (open areas or longer focal distance) or Economy (wooded areas or close-up footage) modes in order to provide the best results for the chosen habitat and target species. The smart IR video feature allows daytime footage to continue recording for as long as movement is detected (up to 5 minutes).

Both trail cameras have a camouflaged case to avoid detection in the field, but the no-glow feature of the Browning Spec Ops Elit HP5 offers further security and is less likely to be spotted in public spaces. 

Setting up

The camera is easy to set up with the provided strap but we would recommend securing it with a Python cable lock if you are using either camera in a public area. The cameras were set up in various locations across Devon (videos) and Sweden (images) to record wildlife in a variety of habitats, including an urban garden.

We also performed a capture distance test of 10m, 20m and 30m (please see our video below).

 

What we found

The cameras have very good sensors and performed well at a distance of 30m.  They are able to detect species of different sizes, from small wrens to larger sparrowhawks in flight. The cameras were triggered by moving leaves and branches, but were also able to pick up less noticeable movement such as rabbits in low light conditions (as seen in the videos). We did find that if you have the camera set up on a tree that has lower hanging branches in view, the branches can prevent the camera from triggering until the target is closer to the camera. We also found that placing the camera too low attracted the attention of nosy badgers, but by placing the camera slightly higher off the ground (around knee height is recommended), we managed to get wonderful images of a badger family (see images below).

The footage and images taken during the day and night were all crisp, and we found that the camera’s field of view is higher than some other trail camera models. This meant that even with the camera placed on the floor, there was no burnout due to the flash oversaturating images of the ground during night time captures.  

The trigger speeds for both cameras are very fast and are an improvement from the earlier Spec Ops and Recon Force models from Browning, ensuring that movement in front of the camera was not missed.

 

If you are looking for a good, top-end camera with excellent image quality, we would highly recommend either camera, choosing the no-glow Browning Spec Ops Elite HP5 if extra security is needed when deploying the camera in areas accessible to the public.

If you would like help with tips and troubleshooting with trail cameras, please check out our other blogs here.

The Browning Spec Ops Elite HP5 can be found here and the Recon Force Elite HP5 can be found here. Our full range of trail cameras can be found here.

If you have any questions about our range or would like some advice on the right product for you then please contact us via email at customer.services@nhbs.com or phone on 01803 865913.

 

Testing the Guide: An Identification Guide to Garden Insects of Britain and North-West Europe

Our second article in our Testing the Guide series looks at An Identification Guide to Garden Insects of Britain and North-West Europe, a photographic identification guide to 150 species of garden insects most commonly found in Britain and north-west Europe.

This guide includes an introduction covering how to attract insects to your garden, advice on photographing insects, a description of insect anatomy, the characteristics of the insect orders included in the guide, and the insect lover’s year, describing the best places to look for different species throughout the different months and seasons of the year.

From there, each species is presented, grouped by order, with keenly observed descriptions to help you identify even the smallest creature, as well as one or two photographs labelled with distinguishing features. In each of these sections, there are details of its life cycle from egg to adult, a calendar showing the time of year when the adult can be seen, and star facts that give further proof of insects’ fascinating lives.

Using the guide

Throughout March, April and May, we tested the identification guide by exploring a garden for a few hours during the day and during the night. The garden is small, with a patch of lawn, bare dirt, a hedgerow of mainly ivy (Hedera helix) and holly (Ilex aquifolium), stone gravel, Japanese camellia (Camellia japonica) and rhododendron (Rhododendron sp.) bushes, a field maple tree (Acer campestre), clumps of daffodils (Narcissus pseudonarcissus) and three-cornered garlic (Allium triquetrum), as well as various other flowering and non-flowering plants. This garden also contains a small insect house which was placed in September of last year. Weedkiller was used once in September but no other chemicals have been used since, nor has the lawn been mowed. Therefore, the garden should be able to support a number of insect species. We attempted to search by eye and by using a tapping tray and stick. Compared to just searching by eye, we found that we had little success with tapping as the vast majority of what we found were spiders and we were unable to identify the few insect species we found using this guide.

What we found
Marmalade hoverfly by H. Ketley

Following the guide, we were able to ID this species as a marmalade hoverfly (Episyrphus balteatus), a small, delicate hoverfly with a unique pattern of twin dark bands separated by lighter bands. As this individual doesn’t have ‘holoptic’ eyes – eyes that meet at the top of the head – we believe this is a female.

Speckled wood by H. Ketley

This guide has a large section on butterflies and moths, covering a number of common species you’ll likely see in your garden and local green spaces. This species is a speckled wood (Parage aegeria), identifiable through its dark colouration and the spots on its hindwing, which have a yellow outer ring, a black inner ring and a white central spot. According to the guide, it is a distinctive species, and there are no similar species listed. However, for those unfamiliar with these species, their underwing pattern could potentially be confused with other butterflies such as walls (Lasiommata megera) or graylings (Hipparchia semele).

Dock bug by H. Ketley

This is a dock bug (Coreus marginatus), a small insect from the family Coreidae. According to the guide, they’re common and widespread in Europe, but in Britain, Ireland and Scandinavia, they’re restricted to the southern parts. They’re identifiable through their shape (upturned, pointed pronotum and broad abdomen with a noticeable scutellum), their red-orange antennae with a black final segment, and their pale-brown colouration. There is variation in the wing membrane colour between individuals, and an important diagnostic feature that can distinguish it from other similar species is the forward-pointing spines between its antenna. This feature can be most easily identified using a hand lens, handheld magnifier or magnifying pot.

Green shieldbug by H. Ketley

This similar-looking species is a (common) green shieldbug (Palomena prasina). Despite its name, this species can range from bright green to bronze, particularly becoming darker prior to winter hibernation. Its brown wing membranes set it apart from similar, non-native species, such as the southern green shieldbug (Nezara viridula), as noted in the guide. If you are able to look closely at one, you’ll be able to see it is covered in tiny black dots, with red eyes, feet and antennae (primarily the last two segments). It can also have a red edge all the way around its thorax and abdomen.

Common malachite beetle by H. Ketley

We also managed to spot this colourful species, which we were able to ID using the guide as a common malachite beetle (Malachius bipustulatus). The red ‘shoulders’ and red spots on the end of the abdomen, helpfully annotated in the guide’s photo, made this species easy to identify.

Using this guide, we were also able to identify a scorpionfly, bluebottle, greenbottle, dark-edged bee-fly, thick-legged flower beetle, two-spot ladybird and a buff-tailed bumblebee.

Our opinion

As noted in the introduction to this guide, there are around 24,000 insect species in Britain, and almost three times that in mainland Europe. And so there will always be species you find in your garden that are not in this field guide, which covers only 150 species.  The breadth of the species covered within the guide perhaps could’ve been expanded, but as it does cover many of the most common species, you are still likely to see a number of these species within your garden and local green spaces. In addition, the paired-down number of species can be useful, as it can be quicker and easier for readers to accurately identify species they’ve found. Therefore, this is still an incredibly useful guide, particularly for naturalists, beginners and those who want a more concise and affordable insect field guide.

An Identification Guide to Garden Insects of Britain and North-West Europe
Dominic Couzens and Gail Ashton

Ash Dieback (Chalara)

In this image it is clear to see how the crown of the mature ash tree is suffering from dieback. (Image by Sarang via commons.wikimedia.org)
What is ash dieback?

Ash dieback is a fungus called Hymenoscyphus fraxineus (known previously as Chalara fraxineus, hence the disease commonly being referred to as ‘Chalara’). The fungus originated in Asia where it is largely harmless to native ash trees; this is because they have developed resistance to it during their long existence side-by-side. It was introduced to Europe around 30 years ago via infected ash saplings, and was first discovered in 2012 in the UK in south-east England. This area remains the most severely affected, although it is systematically spreading throughout the rest of the country.

The fungus overwinters in the leaf litter surrounding the ash tree, and during the summer and autumn it produces fruiting bodies which in turn release huge numbers of spores that land on the leaves of the surrounding trees. They are also carried over large distances by the wind. The spores enter the tree via the leaves and continue to penetrate the plant’s cells, where they eventually block the system responsible for water transport. Young, fragile trees can die very quickly, whereas older, stronger trees may fight back for a while before repeated infections over several years finally kill them.

Why is it a problem and how concerned should we be?

Ash trees play a huge role in woodland diversity and, when present in hedgerows and gardens, are key in connecting fragmented habitats. They are home to a variety of invertebrates, birds and lichens and, as with all trees, contribute to purifying the air and absorbing CO2. As wood from the ash tree is highly valued both for timber and firewood, there is also an economic cost to their loss. This is compounded further by the cost incurred in dealing with the dead trees.

It is expected that, in time, Britain will lose in excess of 80% of its ash trees, incurring a total cost of £15 billion.

How can I recognise the signs of ash dieback?

Ash trees affected by ash dieback initially exhibit dark patches on their leaves which then wilt and go black, and are often shed early. Trees also show characteristic diamond shaped lesions where the branches meet the trunk. Epicormic growth is common as the infected tree becomes stressed – this is where previously dormant buds lower down the trunk begin to show new growth.

The Observatree website features several excellent ID guides, videos and posters designed to help non-specialists identify the presence of ash dieback.

A large lesion on the branch of an infected ash tree. (Image Courtesy of The Food and Environment Research Agency (Fera), Crown Copyright)
What can be done to address the problem?

There is no known cure for ash dieback, although some fungicides have been found to be effective in suppressing the symptoms if they are reapplied every year. Due to the expense of this, they are only really viable for trees of special cultural or heritage value.

Otherwise, the best options moving forwards are to monitor the spread of the disease in the hopes that enough mature trees will show resistance to the fungi that populations can be re-established from their offspring. For this reason, young ash trees should be carefully protected from grazing. Woodlands and parks, particularly those that have lost ash trees, should be replanted with a variety of native and locally grown species to help to protect and improve biodiversity.

In managed parks and gardens, burning the leaf litter around the trees in autumn and winter may be effective in minimising the spread of spores. Similarly, encouraging the public to wash shoes, bikes, buggies and vehicles between visits to different woodlands may also be of some use.

In an infected tree, the centre of the branch commonly turns grey-brown. (Image Courtesy of The Food and Environment Research Agency (Fera), Crown Copyright)
What can I do to help?

There are several things you can do to help:

• Support the Woodland Trust by donating to their Tree Disease Fighting Fund. All donations will go towards efforts to monitor the spread of ash dieback, replanting healthy trees and improving biosecurity measures.
• Practice good woodland hygiene – this includes cleaning shoes, car and bike wheels after visits to woodlands, as well as refraining from taking cuttings or other plant material.
• If you spot an ash tree showing symptoms of ash dieback, you can report it on the TreeAlert website in Britain, or the TreeCheck website in Northern Ireland.

Further reading/resources

Ash | Edward Parker
Ash charts the evolution of this magnificent tree, and its 43 species across the northern hemisphere for the past 44 million years. From its significance in ancient Indo-European cultures, to its remarkable properties in treating Alzheimer’s, Parker looks at the botany, cultural history and medicinal uses of the ash tree.

 

Oak and Ash and Thorn | Peter Fiennes
Immersing himself in the beauty of Britain’s woodlands and the art and writing they have inspired, Peter Fiennes explores our long relationship with the woods and the sad, violent story of how so many have been lost. Just as we need them, our woods need us too. But who, if anyone, is looking out for them?

 

The Ash Tree | Oliver Rackham
Oliver Rackham delves into the history and ecology of the ash tree, exploring its place in human culture, explaining ash disease, and arguing that globalisation is now the single greatest threat to the world’s trees and forests. There is no more urgent message for our times. We cannot go on treating trees like commodities to be bought and sold.

 

Ash | Archie Miles
Ash looks at every aspect of the tree: its many visual manifestations; the uses of the timber for so many different purposes; its cultural significance in place names, folklore, myth and superstition; its inspirational importance for artists, poets and writers; and, of course, the issues arising from the inevitable spread of ash dieback.

This Week in Biodiversity News – 1st June 2022

Climate change

Climate change is weakening trees. Conditions such as extreme heat and drought can impact tree growth, potentially encouraging the formation of shallow root systems. These conditions can also increase the chances of tree diseases thriving. This, along with the potential impact of development, such as road management which damages root systems, is reducing the resilience of trees to stresses such as adverse weather, increasing the likelihood of storm damage.

Climate change and development are weakening trees. Image by Padraic via Flickr

A vulnerable coral species, the pink sea fan, may be likely to spread northwards due to climate change. The species, found in shallow waters from the western Mediterranean to north-west Ireland and south-west England and Wales, is a species of principal importance in England and Wales. A new study, run by the University of Exeter, found that there will likely be an increase in suitable habitats for this species northwards, with existing habitats remaining suitable over the next 60-80 years. The results of this study could hopefully be used to identify areas that are a priority to protect the coral.

Policy

Peatlands are still being burnt, despite the new government ban. Peatlands deeper than 40cm are protected from burning by the new ban introduced last year. However, the RSPB has sent the government evidence of 79 fires that they believe are in breach of these new regulations. Both the RPSB and Greenpeace are calling for a blanket ban on the burning of all peat, regardless of depth. Peatland deterioration has been linked with the release of almost 3.7 million tonnes of carbon dioxide each year in the UK.

Research

New research has shown that sounds can be used to monitor the health of coral reefs. Monitoring the pops, clicks and clacks produced by fish and other marine life can be a non-intrusive, inexpensive and efficient method of tracking the state of coral reefs. Reduced biodiversity in degraded communities results in less activity, and so these reefs do not sound as loud compared to healthy ones. By monitoring decibel levels and comparing soundscapes using underwater microphones, researchers may be able to plan conservation interventions and monitor restoration projects on a long-term basis.

Coral reef sounds could be used to monitor ecosystem health. Image courtesy of Tiket2 via Flickr

A variety of targeted conservation approaches are needed to protect UK bumblebee species. A study, using 10 years of data from Bumblebee Conservation Trust’s citizen science scheme BeeWalk, has found that a ‘one-size-fits-all’ approach to bumblebee conservation may not be an effective method, as there is a wide range of differences between species in the types of habitats they are associated with. Instead, conservation efforts would be better served by being carefully tailored to particular species.

Diatoms, the most important producers of plant biomass in the ocean, could decline due to ocean acidification. These calcifying organisms were previously thought to benefit from ocean acidification as they rely on silica rather than calcium carbonate to build their shells, however, a new study suggests diatom populations could drastically decline. Ocean acidification causes the silicon shells of these species to dissolve more slowly, causing them to sink to deeper water layers. In these layers, these shells chemically dissolve and are converted back to silica. Because of this, the abundance of silica is reduced in the surface layers where new shells are formed, resulting in a decline in diatom populations.

Conservation

Three BioBlitz events held in New South Wales have recorded the recovery of flora, fauna and fungi after the Black Summer bushfires. The UNSW project has found positive signs of recovery; at the latest BioBlitz a total of 2,200 individuals belonging to 823 species were recorded, nine of which are threatened. These citizen science events are proving incredibly useful tools for scientists and researchers to study the prevalence of species across large areas.

The Marine Stewardship Council, an organisation that certifies fisheries under its blue tick sustainability label, has ordered an independent investigation into allegations of shark finning on tuna vessels in certified Pacific fisheries. Between 2019 and early 2020, reports state that silky sharks and a black-tipped reef shark had their fins cut before being discarded overboard. Both species are classified as Near Threatened.

Grey nurse shark by Greg McFall/NOAA via Flickr

In other shark news, Grey nurse sharks are thought to be thriving at a popular dive site in Australia, but there are calls for more research into this critically endangered species. Only around 2,000 individuals are estimated to be left in the wild, following persecution during the 1960s and 70s inspired by the movie Jaws. Bass Point, where a large number of grey nurse sharks were counted, was removed as a critical habitat site in 2013. Conservation biologist Adam Stow, who has been studying this species for nearly 20 years, says more research is needed into the impact of climate change on their movements.

Work begins to turn 99,000 hectares in England into ‘nature recovery’ projects. Five landscape-scale projects in the West Midlands, Cambridgeshire, the Peak District, Norfolk and Somerset are aiming to help tackle wildlife loss and the climate crisis, while also improving public access to nature. The proposed projects range from transforming farmland into chalk grassland to restoring dewponds and sustainably managing wetlands.

Extinctions

According to a new report, two-fifths of Britain’s butterfly species are at risk of becoming extinct. The Butterfly Conservation wildlife charity has released a ‘Red List’, which includes half of British butterfly species, a 26% increase from 10 years ago. There are a number of factors causing this decline but the main ones highlighted have been habitat loss, land-use change and climate change.

The NHBS Guide to UK Hoverflies: Part 2

Hoverflies, of the insect family Syrphidae, are often to be found hovering around flowers and, for this reason, are known as flower flies in many parts of the world. The adults of most species feed largely on nectar and pollen making them important pollinators. Their larvae eat a range of foods; some feed on decaying plant and animal matter whilst others are important predators of aphids, thrips and other insects commonly considered to be ‘crop pests’. Although completely harmless to humans and other mammals, many hoverfly species mimic stinging wasps or bees in an effort to protect themselves from predation.

This is the second instalment in our two part guide to UK hoverflies, in which we cover many of the common species that you are likely to encounter in your garden or local outdoor space. Part one can be found here.

Eristalis pertinax

Distribution: Widespread throughout Britain and Ireland.
Habitat: E. pertinax can be found in a number of habitats, including woodlands, gardens and moorland. 
What to look for: Similar in size and appearance to E. tenax (see The NHBS guide to UK hoverflies: Part 1), the easiest character to use to identify this species is the yellow tarsi (the last segments of the leg) on the front and middle legs. The abdomen tapers towards the end, giving it a triangular shape that can also help to separate this species from E. tenax. 
Months active: March to November, with peaks in both May and August.
Did you know: This is one of the first species to emerge in the spring, when males can often be seen defending territories in woodland rides and around flowers. 

Eristalis pertinax. Image by Gail Hampshire via Flickr.

The Eristalis genus includes a number of common species that are likely to be encountered in gardens, such as E. pertinax and E. arbustorum. The May issue of British Wildlife magazine includes an article by Roger Morris and Stuart Ball that provides an introduction to the Eristalis genus, and includes an identification key to the ten Eristalis species that occur in the UK. 

Baccha elongata

Distribution: Widespread throughout Britain and Ireland, although less common in parts of Scotland.
Habitat: Prefers shaded spots, such as woodland margins and hedgerows.
What to look for: Although generally overlooked due to its small size, B. elongata is unmistakable because of its long, slender, wasp-like abdomen.
Months active: April to November, with peaks in both May and September.
Did you know: Unlike many other hoverflies, B. elongata is rarely seen basking in sunlit areas but tends to be found in low, shaded vegetation. The predatory larvae feed on a number of aphid species, such as Nettle Aphid and Bramble Aphid.

Baccha elongata. Image by Frank Vassen via Flickr.

Episyrphus balteatus

Distribution: Widespread throughout Britain and Ireland.
Habitat: A wide range of habitats, including gardens and woodlands.
What to look for: Episyrphus balteatus, often known as the Marmalade Hoverfly, is an easily recognisable species and one of the most common hoverflies in the UK  – it won’t take too long for you to spot this regular garden visitor. Each of the abdominal segments has two black bands separated by orange bands. This pattern is unique to this species, but the overall colouration of individuals can vary depending on the temperature at which the larvae develop. 
Months active: Individuals can be recorded in all months of the year, but there is usually a peak in numbers in July.  
Did you know: The arrival of huge numbers of migrants from mainland Europe can sometimes lead to reports in the media of a mass influx of ‘wasps’. 

Episyrphus balteatus. Image by Gail Hampshire via Flickr.

Scaeva pyrastri

Distribution: Widespread in England, Wales and Ireland, but much less common in Scotland.
Habitat: Can be found in a variety of habitats, including gardens and woodlands.
What to look for: White, comma-shaped spots on the abdomen are a key identification feature, but completely black individuals can occur. 
Months active: May to November, with a peak in August.
Did you know: S. pyrastri is a migratory species and its numbers in Britain vary greatly between years.  

Scaeva pyrastri. Image by Frank Vassen via Flickr.

Leucozona lucorum

Distribution: Widespread throughout Britain and Ireland, although less abundant in northern Scotland.
Habitat: Woodland rides and edges, and hedgerows.
What to look for: The black wing clouds and broad creamy markings on the second abdominal segment are distinctive characteristics of this species. Confusion can occur with the similar Cheliosa illustrata, but the yellow scutellum (a shield-shaped segment behind the thorax) of L. lucorum will help with identification. 
Months active: Between May and August, with a peak in May and June.
Did you know: L. lucorum is primarily a spring species, but in some years there is a second generation in midsummer. 

Leucozona lucorum. Image by Gail Hampshire via Flickr.

Helophilus pendulus

Distribution: Widespread throughout Britain and Ireland.
Habitat: A wide range of habitats, including gardens.
What to look for: A very eye-catching hoverfly with pale, longitudinal stripes on its thorax and a yellow face with a dark central stripe. It is possible to confuse this species with H. hybridus, although the yellow markings on the second and third abdominal segments are separated by a black band. 
Months active: Between April and November with a peak in July.
Did you know: H. pendulus is commonly seen basking on leaves and often produces a buzzing sound while doing so. 

Helophilus pendulus. Image by Nick Goodrum via Flickr.

Syritta pipiens

Distribution: Widespread in Britain and Ireland, although less abundant in parts of northern Scotland.
Habitat: A variety of habitats and common in gardens.
What to look for: Despite being a small, slender species, S. pipiens is instantly recognisable by the swollen hind femora. The sides of the thorax are also dusted grey.  
Months active: April to November, but more abundant in late summer. 
Did you know: Male S. pipiens are highly territorial and will force each other to move backwards and forwards until one admits defeat and gives up. 

Syritta pipiens. Image by Chris via Flickr.

Volucella zonaria

Distribution: Widespread in southern England and parts of Wales.
Habitat: A variety of habitats, including gardens and parks in urban areas
What to look for: Britain’s largest hoverfly, this species is often known as the Hornet Hoverfly due to the strong yellow-and-black bands on the abdomen and the impressive size (wing length can be between 15.5mm and 19.5mm). The only other hoverfly that V. zonaria could be confused with is V. inanis, but the latter is largely yellow underneath whereas V. zonaria is chestnut coloured with broad black bands. 
Months active: May to November, with a peak in August. 
Did you know: V. zonaria is a relatively recent addition to the British fauna. It first colonised the south of England in the 1930s and its range is rapidly expanding. The larvae live in the nests of social wasps, such as the Hornet and Common Wasp. 

Volucella zonaria. Image by Tim Worfolk via Flickr.

Sphaerophoria scripta

Distribution: Widespread in England and Wales, but only recorded from the east coast of Ireland and less abundant in northern England and Scotland. 
Habitat: Grasslands.
What to look for: Identifying individual species in the Sphaerophoria genus, particularly females, can be extremely difficult. Male S. scripta can be easier to identify as the abdomen is much longer than the wings and has broad yellow bands, although the markings can vary. Confusion can occur with S. batava and S. taeniata, as these two species also have yellow bands; examination of the male genitalia is the only way to determine identification. 
Months active: Between April and November, with a peak in July and August
Did you know: This is the most common Sphaerophoria species and is often found in grassland. There is no resident population in northern Britain, but numbers are boosted in some years by an influx of migrant individuals. 

Sphaerophoria scripta. Image by Sebastien Faillon via Flickr.

Chrysotoxum bicinctum

Distribution: Widespread in Ireland and southern England, but less common in northern England and Scotland. 
Habitat: Open grasslands and grassy woodland rides.
What to look for: The yellow bars on the second and fourth abdominal segment and the chocolate-brown patches on the wings make this wasp mimic instantly recognisable. 
Months active: May to September, with a peak between June and August. 
Did you know: Members of the Chrysotoxum genus are easy to recognise due to their long antennae which point forwards. Other hoverfly groups with similar antennae do not have the yellow-and-black markings of Chrysotoxum.  

Chrysotoxum bicinctum. Image by Martin Andersson via Wikipedia.

Cheilosia illustrata

Distribution: Widespread throughout Britain and Ireland, although less abundant in the north-east of Scotland.
Habitat: Hedgerows and woodland edges where umbellifers such as Hogweed or Angelica are present.
What to look for: Not an entirely believable bumblebee mimic, C. illustrata has a band of pale hairs at the end of the abdomen and dark wing clouds. It is possible to mistake this species for Leucozona lucorum, but the black face and black scutellum of C. illustrata help to distinguish it.
Months active: April to September, peaking in July.
Did you know: The larvae of this species mine the roots and stems of large Hogweed plants and the adults are often observed feeding on the flowers. 

Cheilosia illustrata. Image by S. Rae via Flickr.

Recommended books and equipment

Britain’s Hoverflies: A Field Guide
£17.99 £24.99

A beautifully illustrated photographic field guide to the hoverflies of Britain, focusing on the species that can be most readily identified.

 

 

British Hoverflies: An Illustrated Identification Guide
£37.50

In this classic work by Stubbs and Falk, 276 species are described. Their identification is made easy by the extensive keys which incorporate over 640 line drawings.

 

60ml Collecting Pot
From £0.35

These small sampling containers are made from see-through polypropylene and have secure screw-on lids. They are ideal for the temporary storage of specimens.

 

 

Opticron Hand Lens (10x 23mm)
£12.95 £14.95

Observe the finer details of your specimen with this high-quality 23mm doublet lens, the most commonly recommended magnifier for all types of fieldwork.

 

Sweep Net
£31.99

This high-quality sweep net is designed for catching insects and other bugs from long grass and shrubs

 

All prices are correct at the time of posting, but may change at any time.
Please see nhbs.com for up to date pricing and availability.

No Mow May 2022

Just days into May the flowers begin. Image – Oli Haines

Throughout May 2022 Plantlife have once again made their impassioned annual plea for garden owners across the UK to resist the urge to mow lawns and tidy up their gardens and to join in with #NoMowMay. It’s a simple enough premise to leave grassy areas alone for a month, and it has huge benefits for biodiversity at this time of year to do so, giving a wide variety of flowering plants a chance to bloom early in appeal to our rich network of vital pollinators.

As in 2021, we here at NHBS have participated this year by letting the grassy areas on our premises flower and the results were quickly quite astounding. Within days there was a carpet of daisies and dandelions, Germander Speedwell and Black and Spotted Medic, and, as the month progressed and we explored further, the picture grew more and more complex. Tangles of Common Vetch, Creeping Buttercup and Common Mouse-ear proliferated, and tall fronds of Beaked Hawk’s Beard, Ribwort Plantain and Prickly Sow-thistle appeared. Hidden deep within a mixed mat of grasses the miniscule flowers of Cut-leaved Crane’s-bill, Thyme-leaved Speedwell and Scarlet Pimpernel flourished and, at the lawn edges, tall stands of Garlic Mustard and Cleavers towered over the last of the seasons Bluebell flowers.

It can still feel strangely radical to let an area of public space, or even a private garden, to grow wild. Perhaps it can feel like going against the flow to sit back and not mow or trim the grass, and to embrace a modicum of wild chaos. Much of our wildlife relies on the flowering plants that we suppress with our tidiness and our control of lawns. Multitudes of beetles, bees, ants, moths and butterflies have evolved alongside plants that, given half a chance, can still thrive in our green spaces. No Mow May offers us a glimpse into this rich relationship, this conversation in time, and it provides a lifeline. One flower that showed up in our lawn here, by way of an example, is the Cuckoo flower or Lady’s Smock, a light and elegant pink flower of grasslands that is almost exclusively selected by the Orange-tip (and Green-veined White) butterfly in spring to lay their eggs on, as it feeds the caterpillars when they hatch. Growing up to 50cm in height its reach is well within the mowing range.

In addition to the No Mow May initiative, Plantlife have also introduced Every Flower Counts, a citizen science survey that asks participants to count, record and report back the flowers found in a single metre squared patch of lawn . This will enable them to gather important data on the impact that leaving areas to grow can have on abundance and biodiversity.

As May winds to a close, species are still beginning to emerge in our lawn ready to flower in June: Spear Thistle, Oxeye Daisy, members of the Carrot family and, with a final flourish of the month, a Bee Orchid slowly opens its blooms right by the footway, surprisingly cryptic until you meet it at ground level.

Bee Orchid (Ophrys apifera). Image – Oli Haines

We hope that we can leave our grass uncut for a little longer so we can see who’s still there to flower, and that those of you who have participated in No Mow May may feel inspired to do the same.

Below is a list (in no particular order) of the flowering plants we discovered on our premises during No Mow May this year and a small selection of guides for wildflowers and grasses, plus some suggested reads for those who have inspired to take wild gardening further.

  1. White Clover – Trifolium repens
  2. Red Clover – Trifolium pratense
  3. Common Vetch – Vicia Sativa
  4. Germander Speedwell – Veronica chamaedrys
  5. Common Speedwell – Veronica persica
  6. Thyme-leaved Speedwell – Veronica serpyllifolia
  7. Common Dandelion – Taraxacum officinale
  8. Common Daisy – Bellis Perennis
  9. Meadow Buttercup – Ranunculus acris
  10. Creeping Buttercup – Ranunculus repens
  11. Cuckoo Flower – Cardamine pratensis
  12. Yarrow – Achillea millefolium
  13. Spotted Medick – Medicago Arabica
  14. Black Medick – Medicago lupulina
  15. Bluebell – Hyacinthoides non-scripta
  16. Cut-leaved Crane’s-bill – Geranium dissectum
  17. Common Mouse-ear – Cerastium fontanum
  18. Ribwort Plantain ­– Plantago lanceolata
  19. Bee Orchid – Ophrys apifera
  20. Herb Robert – Geranium robertianum
  21. Oxeye daisy – Leucanthemum vulgare
  22. Beaked Hawk’s-beard – Crepis vesicaria
  23. Catsear – Hypochaeris radicata
  24. Broad-leaved Dock – Rumex obtusifolius
  25. Sheep’s Sorrel – Rumex acetosella
  26. Southern Marsh/spotted Orchid Hybrid
  27. Creeping Cinquefoil – Potentilla reptans
  28. Primrose – Primula vulgaris
  29. Common Ragwort – Senecio jacobaea
  30. Hemlock – Conium maculatum
  31. Hemlock Water Dropwort – Oenanthe crocata
  32. Cuckoo-pint – Arum alpinum
  33. Scarlet Pimpernel – Anagallis arvensis
  34. Nipplewort – Lapsana communis
  35. Bristly Oxtongue – Helminthotheca echioides
  36. Cleavers – Galium aparine
  37. Ivy-Leaved Toadflax – Cymbalaria muralis
  38. Wood Avens – Geum urbanum
  39. Garlic Mustard – Alliaria petiolata
  40. Red Valarian – Centranthus ruber
  41. Hoary Willowherb – Epilobium parviflorum
  42. Broad-leaved Willowherb – Epilobium montanum
  43. Fringed Willowherb – Epilobium ciliatum
  44. Procumbent Pearlwort – Sagina procumbens
  45. Groundsel – Senecio vulgaris
  46. Cornsalad – Valerianella locusta
  47. Spear Thistle – Cirsium vulgare
  48. Prickly Sow-thistle – Sonchus asper
  49. Common Nettle – Urtica dioica
  50. Lesser Trefoil – Trifolium dubium

 Suggested books and equipment

Wild Flower Flowcharts Species: ID the Easy Way
Spiralbound | March 2022
£6.99

 

 

A Field Guide to Grasses, Sedges and Rushes
Spiralbound | April 2016
£11.99

 

 

 

 

The Wild Flower Key: How to identify wild flowers, trees and shrubs in Britain and Ireland
Paperback | March 2006
£24.99

 

 

 

Harrap’s Wild Flowers: A Field Guide to the Wild Flowers of Britain & Ireland
Paperback | November 2018
£19.99

 

 

 

Collins Wild Flower Guide: The Most Complete Guide to the Wild Flowers of Britain and Ireland
Paperback | June 2016
£24.99

 

 

 

Making a Wildflower Meadow: The Definitive Guide to Grassland Gardening
Paperback | February 2015
£16.99

 

 

 

Wildlife Gardening: For Everyone and Everything
Paperback | April 2019
£14.99

 

 

 

Q1 Quadrat
£14.99

 

 

 

 

Q2 Quadrat
£15.50

 

 

 

 

Opticron Hand Lens 23mm 10x Magnification
£12.95 £14.95

 

 

All prices correct at the time of this article’s publication.

Book Review: Birds, Beasts and Bedlam by Derek Gow

Birds, Beasts and Bedlam: Turning My Farm into an Ark for Lost Species is an eclectic mix of stories from Derek Gow’s past and from the varied people he’s met and worked with. Opening with an account of his expedition to see bison in Poland, Gow laments the loss of ‘great beasts’ from Britain. We’ve lost much of our megafauna, including steppe bison; aurochs; brown, polar and cave bears; Eurasian and Irish elk; lynx; and wolves. Some of these losses, along with the current rate of habitat destruction, have drastically changed how our ecosystems function.

Derek Gow is a reintroduction expert, farmer and author, best known for his work with beavers, white storks, water voles and wildcats. His first natural history book, Bringing Back the Beaver, was a highly acclaimed success, detailing his firsthand account of the reestablishment of beavers in waterways across England and Scotland. Following Gow’s rewilding and farming adventures, from his first attempt at keeping livestock as a child to his time working at zoos and captive breeding programmes, Gow’s new memoir describes his battles with creating a viable farm and how he is repairing the damage this caused to the land and wildlife. 

In 2006, Gow bought a farm next to his property in South Devon. In chapter three ‘Not a Lark or a Lizard Lived There’, Gow details the quiet decline of wildlife on his farm and his slow realisation of the damage he caused by following conventional farming practices. He tells of his final straw moment, when a small mammal trapping course run on his land only turned up two woodmice. The lack of voles indicated a much wider absence of wildlife within the farm, such as the loss of barn owls and kestrels.

Male kestrel offering a vole to a female. Image by Francesco Veronesi via Flickr

After realising the damage that was occurring, Gow started to deconstruct his farm, selling off his livestock and began to try to rejuvenate the land. Through excavations, fencing and accidental escapees, a complex series of watercourses and wetlands were created. Birds, otters, amphibians and insects started to return. But this wasn’t enough. Gow introduced Heck cattle, Iron Age pigs (a hybrid of wild boar and Tamworths), mouflon sheep, Exmoor ponies and even water buffalo to replicate the ecosystem roles of Britain’s lost megafauna. These helped shape not only the species composition and trophic structure of the ecosystem, but also the physical structure of the habitats, conserving and promoting biodiversity. Gow describes how the cattle gouged banks and dug pits in pastures, how pigs created wallows that supported tadpoles and dragonfly larvae, and how the presence of grazing ponies has resulted in an irregular, wilder edge where pastures and woods meet. 

Mouflon by leopoldo de castro via Flickr

Throughout the later chapters, Gow shares the conservation history and reintroduction attempts of two ailing UK species, the water vole (Arvicola amphibius) and the pool frog (Pelophylax lessonae). Water vole populations have significantly declined in recent decades due to predation by the invasive American mink (Neovison vision), habitat degradation, historical persecution and pollution. The reduction in waterways and habitat corridors, the removal of bankside vegetation and the urbanisation of floodplains are among the many ways water vole habitats are being destroyed.  Gow recounts the process of creating a successful captive breeding program for water voles, sharing the many mistakes that were made before they found the right cage design. Thousands of water voles have been bred for release projects, helping to boost declining populations.

Human encroachment into watercourses is also thought to have been one of the causes of the extinction of pool frogs in the UK. Reintroductions from populations in Sweden have been underway since 2005. Perhaps unsurprisingly, Gow links both the reintroduction of this species and the efforts for water voles to the reintroduction of beavers. As anyone who has read Bringing Back the Beaver will know, beavers are ecosystem engineers and shape the habitats they live in. Their actions provide a far more sustainable and natural practice for creating more suitable habitats to facilitate rewilding and the reintroduction of other species.

Beaver pond in Yellowstone National Park. Image by NPS / Neal Herbert via Flickr

Birds, Beasts and Bedlum is a fun, engaging memoir, filled with excentric tales and artful insights into the world of farming, conservation and rewilding. Ending on a lament at the often slow, overcomplicated process of reintroductions and rewilding, this book highlights the need for a better-developed system and large-scale reshaping of the landscape, with a final call for the return of the wolf. 

Birds, Beasts and Bedlam: Turning My Farm into an Ark for Lost Species
By: Derek Gow
Hardback | June 2022

 

 

 

 

How to use a quadrat

Surveying plants within a quadrat (a)
What is a quadrat?

A quadrat is a square frame, usually constructed from wire or plastic-coated wire, although they can be made from any sturdy material. Most commonly they measure 50cm x 50cm (i.e. 0.25m2), and may have further internal divisions to create either 25 squares each measuring 10cm x 10cm or 100 squares measuring 5cm x 5cm. Some frames are also collapsible which allows you to connect several pieces together to create larger sample areas.

What are quadrats used for?

Quadrats are used to survey plants or slow-moving/sedentary animals. They can be used either on land or underwater to gain an estimate of:

  • total number of an individual (or several) species.
  • species richness/diversity – the number of different species present in an area.
  • plant frequency/frequency index – the uniformity of a plant’s distribution within a surveyed area (not a measure of abundance).
  • percentage cover –  useful in situations where it is difficult to identify and count individual plants, such as grasses or mosses.

By deploying several quadrats it is possible to compare any of these factors either spatially (for example in locations with different light or pH levels) or over time, such as at different points throughout the year.

Quadrats being used along an intertidal transect to study rocky shore ecology (b)
How to use a quadrat

Most surveys require that quadrats are placed randomly within the survey site. One way to ensure that placements are truly random is to divide your survey area into quadrat-sized spaces and then use a random number generator to choose x and y coordinates. The quadrat can then be placed in the appropriate position. The number of samples you require will depend largely on the size of your survey site and the amount of time/manpower you have available. A minimum of ten samples should ideally be used.

In some situations, more specific placement of the quadrats is required. For example, when studying the changes in species presence/abundance on a shoreline, you may wish to take samples at regular intervals along a transect up the beach.

Creating a species list

One of the simplest ways of using a quadrat is to create a species list. To do this, the quadrat is placed randomly several times within the target area and the plants present within them are recorded. This will not provide any information on abundance or distribution, but will be a useful guide as to the species that are present at the time of sampling.

Estimating the total number of a species

For plants or animals that are easy to count, it is possible to estimate their total numbers for your survey area. To do this, simply count the number present in a series of quadrat samples then divide the total by the number of samples to get an average count per quadrat. If you know the dimensions of your entire survey site you can then multiply this up to get an estimate of the total number of a species present.

Estimating plant frequency/frequency index

To calculate plant frequency or frequency index, you simply need to note down whether the target species is present or absent within each quadrat sampled. The number of quadrats in which the species was present should be divided by the total number of samples taken and then multiplied by 100 to get the frequency as a percentage. For example, in a survey where 10 samples were taken, dandelions were found in 6 of these. This would give a frequency index of (6/10) x 100 = 60%.

Estimating percentage cover

For species in which it is difficult to count individual plants (e.g. grasses and mosses) it is easier to estimate percentage cover. For this purpose a quadrat with internal divisions is recommended – one with 100 5cm x 5cm squares is particularly useful. Results from several quadrats can then be averaged and scaled up to get an estimate for the entire survey area.

Important things to remember
Quadrat with 25 10cm x 10cm divisions

• The number of samples you take (i.e. the number of times you deploy your quadrat during your survey) will affect the reliability of your results. Sample sizes which are too small are much more likely to be affected by anomalous counts (e.g. localised clusters of individual species). On the other hand, planning for too many samples can create an impractical workload.

• Bear in mind that there will always be observer bias. By their nature, flowering plants are easy to overestimate and low-growing species are more likely to be missed.

• Take care to make sure that your quadrats are randomly placed if your survey design requires this. It is easy to subconsciously place them where there are large numbers of flowers or easy to count species. Using a coordinate-based system will solve this problem.

Quadrats available from NHBS

At NHBS we sell a selection of high-quality quadrats, designed to be strong, long-lasting and durable.

Q1 Quadrat
Made from heavy gauge steel wire with zinc plating, the Q1 Quadrat measures 0.5m x 0.5m and has no divisions.

 

 

Q2 Quadrat
The Q2 Quadrat is made from heavy gauge steel wire with a plastic protective coating. The 0.5m x 0.5m frame is subdivided into 25 squares for sampling dense vegetation or species-poor habitats.

 

Q3 Quadrat
The Q3 Quadrat is made from heavy gauge steel wire with plastic coating. The 0.5m x 0.5m frame is subdivided into 100 squares for calculating percentage cover or making presence/absence recordings.

 

Q4 Quadrat
The Q4 Quadrat is a strong collapsible quadrat made from four pieces of heavy gauge steel wire with zinc plating. A single Q4 frame will make a 0.5m x 0.5m open frame without divisions, suitable for general vegetation surveys. Additional units can be used together to make a variety of quadrats, e.g.. 1m x 1m or 1m x 0.5m. Being collapsible means it is also ideal for travel.

Photo credits:
(a) U.S. Fish and Wildlife Service Headquarters via Flickr (CC BY 2.0)
(b) USFWS Pacific Southwest Region via Flickr (CC BY 2.0)