Month: April 2017

The NHBS Guide to Small Mammal Trapping

Please note we have published an updated guide to small mammal trapping with up to date information on the latest equipment and guides available. Some of the products described in this article may therefore be outdated or unavailable

Field vole (Microtus agrestis)

Small mammals form a vital component of our terrestrial ecosystems, both by contributing to overall biodiversity and providing prey for carnivores such as owls, pine martens and weasels. Survey data for many of our small mammal species is insufficient for them to be assessed as part of the UK BAP process and so supporting our national monitoring programme is incredibly important.

One of the most common ways of monitoring small mammals is through the use of live traps. These allow a range of species to be monitored simultaneously, and also allow biometric data such as weight and sex to be collected. In addition, estimates of population size and structure can be calculated using capture-mark-recapture (CMR) techniques. The use of live traps is also a great way for getting volunteers involved and providing them with an up-close experience of the animals they are passionate about.

Live-catch techniques, however, do have a few disadvantages in that populations can be affected by disturbance or mortality. Live-trapping is also unsuitable in certain areas (such as urban or busy rural regions) and requires a relatively large amount of time and expenditure.

Here we will take a look at some of the most commonly available live-traps used for small mammal survey.

Longworth Trap

Longworth Small Mammal Trap

The Longworth trap is made from aluminium which makes it lightweight for field use. This trap has been widely used in the UK for many years.

The trap consists of two parts: a tunnel which contains the door tripping mechanism, and a nest box, which is attached to the back of the tunnel. The nest box provides a large space for food and bedding material to ensure that the trapped animal is comfortable until release.

Advantages
• Widely used for many years; well documented in scientific literature
• Lightweight and durable
• Sensitivity of the trip mechanism can be adjusted
• Door can be locked open for pre-baiting

Disadvantages:
• Expensive
• Replacement parts not available
• Larger species can occasionally trip the trap without being caught
• Pygmy shrews may be too light to trigger the trap mechanism

Sherman Trap

Sherman Trap

Sherman traps work by use of a triggered platform which causes the door to shut when the animal enters. It folds down to a size and shape which is easy to transport.

Sherman traps are available in a range of different sizes to suit the species that you are hoping to catch. They can be purchased in aluminium or as a galvanised version which is more resistant to rusting.

Advantages:
• Lightweight and foldable – easy to transport and store
• Different sizes available, including long versions
• Easy to clean

Disadvantages:
• Difficult to add bedding/food as this interferes with the trap mechanism
• Traps may distort over time with repeated folding
• Danger of long tails being trapped in the door

 

Economy Mammal Trip-Trap

Economy Mammal Trip-Trap

The Economy Trip-Trap provides a cheaper alternative to other mammal traps.  It has a traditional treadle design which closes the door behind the animal when it enters the trap.

This lightweight trap is suitable for short-term or occasional use and is also popular for trapping mice indoors either for surveying or for relocation.

Advantages:
• Cheap and lightweight
• Transparent for easy inspection
• Good for indoor use

Disadvantages:
• Doesn’t work well in wet/humid conditions
• Can’t pre-bait or change trigger sensitivity
• Trapped animals may chew through the trap

Pitfall Traps

P2.5 litre Plastic Bucketitfall Traps consist of a container which is sunk into the ground, into which small mammals can be caught. Traps can be baited if required and drift fencing can also be used to direct animals into the trap.

Small cans or buckets make ideal pitfall traps. If using buckets, lids can be fitted when not in use, which means that traps can remain in situ for extended periods of time.

Advantages:
• Able to catch multiple individuals
• Low maintenance

Disadvantages:
• More labour intensive than box traps to set up
• Trapped animals may attack eachother or be eaten by predators
• May become waterlogged in damp areas or in bad weather

Other survey methods

Other methods of surveying for small mammals include the analysis of owl pellets for mammal remains and the use of dormouse nest tubes. Hair and footprint tubes are also useful as well as searching for field signs such as tracks and faeces.

A comprehensive monitoring programme will most likely involve a combination of these methods, depending on the availability of participants and volunteers and the type of habitat present locally.

If you are interested in becoming involved in mammal survey in the UK, take a look at the Mammal Society website where you will find information on local recording groups, training opportunities and the latest mammal-related research.

Our full range of mammal traps can be found on our website.

Please note we have published an updated guide to small mammal trapping with up to date information on the latest equipment and guides available. Some of the products described in this article may therefore be outdated or unavailable

 

Book Review – How to Tame a Fox (and Build a Dog)

How to Tame a Fox (and Build a Dog)How to Tame a Fox (and Build a Dog): Visionary Scientists and a Siberian Tale of Jump-Started Evolution

Written by Lee Alan Dugatkin & Lyudmila Trut

Published in March 2017 by Chicago University Press

How to Tame a Fox (and Build a Dog) tells a remarkable story about a remarkable long-term experiment you will most likely never have heard of. I hadn’t, despite my background in evolutionary biology. When the announcement for it crossed my desk a month or so ago, its subtitle immediately grabbed my attention.

For more than 60 years, Russian scientists have been cross-breeding captive foxes in Siberia, selecting for tameness, in a bid to learn more about the evolutionary history of animal domestication. Written by evolutionary biologist and science historian Lee Alan Dugatkin and Lyudmila Trut, who has been part of this experiment for close to six decades, it tells the story from its inception.

Back in 1952, geneticist Dmitri Belyaev had many questions regarding domestication. Though the breeding techniques were well understood, how did domestication start? The wild ancestors of today’s domestic animals would have likely run away or attacked humans, so what changed to make domestication possible? Being the lead scientist at a state laboratory that helped fur breeders produce more beautiful and luxurious fox pelts, he had both the knowledge and the means to tackle these questions. His plan? Experimentally mimic the evolution of the wolf into the dog using its close genetic cousin the fox. It was bold, both in its timescale, likely needing years – even decades – to yield results, but also in its timing. You see, Russia was still under the communist rule of Stalin, and one of his protegees, the poorly educated agronomist Trofim Lysenko, was waging a war on the “western” science of genetics. Scientists were expelled, imprisoned, and even murdered over their career choice. But Belyaev, having lost a brother this way, refused to back down. Far from Lysenko’s prying eyes in Moscow, in the frozen wilderness of Siberia, he started his breeding experiments, purporting to improve breeding rates in case anyone did come asking. Lyudmila joined him in 1958, and this book is their story.

It’s a story of science, and the authors do a good job distilling the findings into a reader-friendly format. The results are fascinating as the foxes rapidly evolve from wild animals to tamer and tamer companions that crave human interaction, undergoing a raft of subtle morphological changes in the process. But it’s also very much a human story. Of the women, often local peasants, who came to work at the fox farm, not necessarily understanding the science, but showing immense dedication to the cause. Of the researchers, who developed a deep love for, and connection with the generations of foxes, who rapidly became more dog-like in their behaviour and appearances.

It’s a story of persistence against all odds; the experiments are running to this day and have survived Stalin’s brutal regime, the Cold War, and the dissolution of the Soviet Union, with all the economic turmoil that that caused. And it’s a story of an opportunity most scientists can only dream of: being able to follow up on previous findings and answering questions raised by previous experiments. Uniquely, this played out during (or perhaps was able to keep going because of) a period in which our knowledge of genetics, and the technologies available, kept on developing. The measuring of neurochemicals, epigenetics, PCR, genome mapping, next-generation sequencing… as new questions were being generated, so new techniques became available to probe deeper into the mysteries of the domestication.

The book makes for fascinating reading and is hard to put down once you start it. Highly recommended.

How to Tame a Fox (and Build a Dog) is available to order from NHBS.