Development, validation and application of enhanced-welfare technology for wild small mammal research

Wild small mammals such as mice and voles are common study subjects in many fields of research including ecology, conservation, evolutionary biology and land management. However, current methods for studying these animals usually involve either the repeated setting of live-traps (a capture-mark-recapture approach), or radio-tracking. Both methods raise concerns for animal welfare. Small mammals can lose weight and sometimes die during trap confinement, and radio-tracking involves the attachment of a transmitter to small animals, which can impede their natural behaviour and reduce survival. Importantly, live-trapping is also indiscriminate, such that many captured animals are not required for research, including non-target species or animals that have already been captured and do not need to be captured again.

These traditional approaches are based on simple technology (metal traps or radio-transmitters), yet the technological foundations are available to develop more sophisticated solutions than improve both animal welfare and the quality of scientific data obtained. In particular, microchips (PIT tags) are frequently used to identify individuals with a handheld scanner. However, PIT tag technology has potential far beyond this role. In this proposal, we will tap into this, and develop, validate and apply two novel devices based on PIT tag technology that will reduce unnecessary captures and refine welfare in small mammal studies.

The first is an "intelligent trap", which is capable of making decisions about whether to trap a given animal based on its PIT tag and weight. This will allow species outside a particular size range to be excluded (e.g. shrews that are common by-catch in rodent studies) and prevent unnecessary recapture of tagged animals. It will also have an auto-release feature, allowing collection of faecal samples (commonly required in epidemiological studies) without animals having to stay a full night in traps and be handled for release.

The second device is a "spatial logger" that can monitor the whereabouts of tagged animals. When a tagged animal passes within 30cm of the logger, it's presence is recorded. By placing a set of these across a field site, researchers can monitor individual animal movements and survival without the need to repeatedly capture them or attach radio-transmitters and actively follow them.

We will develop both devices from our current prototypes, validate their performance in the field, and apply them in a study on wild wood mice and bank voles to demonstrate their scientific value and how they improve animal welfare. This study will also show how they facilitate completely novel science that cannot be approached using traditional methods. Specifically, we will use them to ask how social interactions affect the spread of gut bacteria among wild mice. Social interactions are hard to measure, particularly for animals that are small, nocturnal and nest underground. We will use spatial loggers to monitor wood mouse social interactions by placing them across our field site and at burrow entrances, to record who nests with whom and how their home ranges overlap. We will compare this to data on which gut microbes are present in each mouse (using molecular methods applied to faecal samples from traps) to assess how sharing of gut microbes, and which ones in particular, is predicted by patterns of social interaction.

We aim for these two devices to achieve maximum impact through eventual widespread uptake in small mammal research. To achieve this, dissemination and commercialisation plans feature in our proposal, including trialling of devices by four other research groups, a workshop, and communication of findings at a variety of meetings targeting scientists, policymakers and the general public.

Wild small mammals are studied in many research fields, including microbiome ecology, disease ecology, demography and conservation. Two key methods for monitoring these animals are the capture-mark-recapture approach (CMR, i.e. repeat live-trapping) and radio-tracking to monitor movements. Live traps capture many animals not required for research objectives, including non-target species and recaptures. Spending time in traps can significantly reduce animal welfare, causing weight loss and a risk of mortality. Handling before manual release is also stressful. In this proposal, we will develop, optimise and apply two novel devices based on PIT tag technology that will reduce the number of animals used in this type of research, refine their experience, and enable higher quality scientific data to be collected from the animals involved. The first is an intelligent trap, which will allow researchers to selectively trap only those individuals required according to both body mass and ID. This device will also collect body mass data and allow for faecal sample collection without human handling and without animals being in traps overnight, via an auto-release feature. The second is a spatial logger, which records the presence of a PIT tagged animal when it passes a detector. These loggers have low power consumption and can be left in the field for c. 1-2 months, collecting high resolution data on individual whereabouts without human interference. Both devices have remote programming and data retrieval capability. We will apply these devices in our long-term study of wood mice, in order to quantify the 3Rs impact they can achieve and demonstrate their scientific value by using them to ask a novel scientific question about gut microbiome ecology, that has been out of reach with standard techniques. We will support four other research groups to trial these devices, both in the UK and mainland Europe, to establish their use in other species and systems.