Citizen science and the ecology of urban mammals and birds

Background: Compared with groups like birds, many wild mammal species in Britain are relatively cryptic and tend to avoid humans, making them difficult to survey effectively. As well as making it difficult to assess the conservation status of mammal populations, lack of reliable data on spatial and temporal variation in mammal abundance presents an obstacle to understanding and managing impacts of mammal populations on other species of conservation or economic concern. Camera traps, which are triggered by passing animals to capture images recording their presence and activity, can be an effective means of collecting data on mammal presence and activity. The MammalWeb scheme enlists members of the public to deploy camera traps in their gardens or other areas local to them. Images are made available to volunteers via an online platform (www.mammalweb.org) and collaboratively classified to provide information on species occurrence and activity. Given sufficient levels of engagement in a particular habitat or landscape, this initiative has the potential to greatly enhance our understanding of its mammal populations.

Gardens represent one of the most convenient and straightforward habitats in which members of the public can operate camera traps. Additionally, mammal populations in urban habitats are interesting, both in their own right and because of their interactions with other species and with people. While urban habitats are typically associated with reduced biodiversity, urban gardens and other green spaces can serve as significant resources – or even refugia – for wildlife. A number of garden-based citizen science initiatives already enlist members of the public to monitor the occurrence, abundance or activity of certain taxa. One of the largest of these is the British Trust for Ornithology’s Garden Bird Watch (GBW), a survey with approximately 12,000 volunteers, who regularly submit records of birds and, increasingly, mammals observed in their gardens. The data from birds have shown, for example, significant impacts of garden feeding on bird populations and communities (Figure 1), but there is still much more to understand, particularly in relation to the mammals and how these interact with the bird communities, as well as how the management of gardens impacts upon wildlife. Many mammals benefit from supplemental feeding in gardens (Figure 2a), or can access supplemental food from refuse, leading to increases in numbers of species such as foxes and some public concerns over safety. Other charismatic species such as hedgehogs (Figure 2b) have seen dramatic declines in rural areas, but urban populations may be bucking the trend.

This project will link data from MammalWeb and the BTO GBW scheme, as well as those available from other BTO surveys, to improve our understanding of garden-based mammal populations and their interactions with other species. In doing so the project will build capacity within MammalWeb for monitoring over large spatial scales. The findings of the project will have relevance for the fields of citizen science, mammal monitoring, urban ecology and landscape-level conservation management.

Aims: The student will work with staff from both GBW and MammalWeb to build a network of contributors to both projects. They will analyse data collected from this pool of dual-contributors, as well as data collected independently from both schemes and from other BTO surveys. They will use these data to answer key questions, including: (i) could a camera trap loan model be implemented successfully to link MammalWeb and the GBW at a national level? (ii) what factors affect participation in MammalWeb by BTO members? (iii) how do mammal data collected in the BBS relate to those collected by MammalWeb and the GBW over corresponding time periods and regions? (iv) does knowledge of mammal occurrence help to inform occupancy models for key bird species in areas of data overlap? (v) are species’ daily and seasonal activity schedules affected by garden features, homeowner behaviours or the presence of other species? and (vi) do features of gardens that favour higher bird species richness or increased prevalence of key bird species also favour higher wild mammal species richness or increased prevalence of key mammal species?

Novelty and timeliness: There is growing recognition of the need to monitor wildlife at large spatial scales, and of the pivotal role that citizen science can play in this. The increasing affordability of camera traps and the online capacity delivered by the MammalWeb platform provide an excellent opportunity to collaborate with the BTO. This will deliver valuable insights into urban ecology and large-scale monitoring of mammals.

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Image Captions

Figure 1: Changes in bird populations due to garden bird feeding recorded in Garden BirdWatch surveys.,Figure 2: Many of Britain’s mammals are attracted to gardens; (a) foxes and badgers can actually be relatively tolerant of each other, particularly in urban areas where food is provided; (b) Hedgehogs are a much loved native species that are in decline, but there are vast differences between urban and rural populations.


Methodology: The student will work with BTO staff to develop camera trap ’lending libraries’ in selected geographic areas and to maximise impact on mammal species of interest. They will liaise with volunteers to facilitate scheme uptake and use questionnaires and other engagement methods to determine the scheme’s viability at a national level and to assess factors affecting uptake. They will extract information related to distribution, abundance and activity of species recorded by camera traps in this scheme. They will use appropriate analyses (e.g., occupancy modelling, spatial capture recapture, distance analysis, functions in the R package “activity”, multivariate ordination, generalised mixed/additive models, machine learning) to contrast the findings of this scheme with those drawn from other types of monitoring, and to explore patterns of occurrence, abundance, activity and diversity among the species recorded, and in relation to other environmental covariates. A student who is open to travel may also visit and work with MammalWeb’s European partners, exploring best practice and the potential to expand the project’s approach and findings.

Project Timeline

Year 1

Gaining familiarity with the schemes and available data; fieldwork; setting up loan scheme and recruiting participants; training in analytical approaches. Literature review to identify key questions and objectives from data collection.

Year 2

Developing and deploying questionnaires or complementary methods to engage with GBW participants; developing models for individual species to address project objectives.

Year 3

Continued modelling for individual species; modelling species diversity; commencing write-up and preparation of initial analysis for publication.

Year 3.5

Conclude write-up and further submission of outputs for publication.

& Skills

The student will receive training in the use of camera traps and associated analysis of data. The student will gain experience working with organisations and schemes at the forefront of citizen science in the UK. They will also receive training in data management and cutting-edge analytical techniques (areas of particular expertise at BTO). The student will also develop skills in project management, time management, written and oral communication as well as in presentations over the course of the project. The supervisors have complementary expertise to provide the necessary training and support fand the close proximity of Durham and Newcastle will facilitate interaction and collaborative supervision. The student will also make regular visits to the BTO to benefit from their expertise and guidance.

References & further reading

• Green, S.E., Stephens, P.A., Whittingham, M.J & Hill, R.A. (2022) Camera trapping with photos and videos: implications for ecology and citizen science. Remote Sensing in Ecology and Conservation. https://doi.org/10.1002/rse2.309
• Hsing, P.-Y., Bradley, S.P., Kent, V.T., Hill, R.A., Smith, G.C., Whittingham, M.J., Cokill, J., Crawley, D., MammalWeb Volunteers, Stephens, P.A. (2019) Economical crowdsourcing for camera trap image classification. Remote Sensing in Ecology and Conservation. 4, 361-374. https://doi.org/10.1002/rse2.84
• Hsing, P.-Y., Hill, R.A., Smith, G.C., Bradley, S.P., Green, S.E., Kent, V.T., Mason, S.S., Rees, J.P., Whittingham, M.J., Cokill, J. & Stephens, P.A. (2022) Large-scale mammal monitoring: the potential of a citizen science camera-trapping project in the UK. Ecological Solutions and Evidence, https://doi.org/10.1002/2688-8319.12180
• Mason, S.S., Hill, R.A., Whittingham, M.J., Cokill, M.J., Smith, G.C. & Stephens, P. (2022) Camera trap distance sampling for mammal population monitoring: lessons learnt from a UK case study. Remote Sensing in Ecology and Conservation 8: 717–730. https://doi.org/10.1002/rse2.272
• Stephens, P.A., Mason, L.R., Green, R.E., Gregory, R.D., Sauer, J.R., Alison, J., Aunins, A., Brotons, L., Butchart, S.H.M., Campedelli, T., Chodkiewicz, T., Chylarecki, P., Crowe, O., Elts, J., Escandell, V., Foppen, R.P.B., Heldbjerg, H., Herrando, S., Husby, M., Jiguet, F., Lehikoinen, A., Lindstrom, A., Noble, D.G., Paquet, J., Reif, J., Sattler, T., Szep, T., Teufelbauer, N., Trautmann, S., van Strien, A.J., van Turnhout, C.A.M., Vorisek, P. & Willis, S.G. (2016) Consistent response of bird populations to climate change on two continents. Science 352, 84-87. https://doi.org/10.1126/science.aac4858

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