Citizen science and the ecology of garden birds and mammals


Background: Globally, urbanisation represents a major process of landscape-scale habitat change. Urbanisation is typically associated with both reductions in biodiversity and altered patterns of species’ behaviour. In this context, urban gardens and other green spaces can serve as significant resources – or even refugia – for wildlife. This has prompted increasing interest, within the UK, in wildlife-friendly gardening practices. Urban gardens also represent an important focus for human-wildlife interactions in communities that are increasingly disassociated from the natural world. In order to assess the value to biodiversity of gardens (and of different gardening practices), a number of citizen science initiatives encourage members of the public to record the occurrence and prevalence of certain taxa. Repeated surveys enable monitoring of changes in these measures, potentially linking them to relevant environmental variation. A prominent example of such an initiative is the British Trust for Ornithology’s Garden Bird Watch (GBW). This survey involves approximately 12,000 volunteers, who have provided details of their gardens and garden management, and regularly submit records of birds and, increasingly, mammals observed in their gardens. A smaller but burgeoning scheme is MammalWeb, which enlists members of the public to deploy camera traps in their gardens or other areas local to them. Camera traps are triggered by a combination of movement and body heat to capture images recording the presence and activity of garden mammals (as well as many bird species). The images and associated metadata are made available to volunteers via an online platform ( and collaboratively classified to provide geo-referenced information on species’ occurrence and activity. This project will link data from these two schemes, as well as those available from other BTO surveys. This will yield insights about the complementarity and wider relevance of these schemes, and improve our understanding of interactions between, and requirements of, different taxa. The findings of the project will have relevance for the fields of citizen science, monitoring and urban ecology. Aims: The student will work with staff from both GBW and MammalWeb, helping 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. They will also have access to mammal data collected during the BBS. 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?

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Image Captions

Our gardens can host a variety of charismatic wildlife, like this red fox, captured by MammalWeb contributor Bailey Pilbeam (and released under a Creative Commons Attribution-ShareAlike 4.0 International License,


The student will work with BTO staff to develop camera trap ’lending libraries’ (based on similar models used to give BTO volunteers access to acoustic equipment) in selected geographic areas. They will liaise with volunteers to facilitate scheme uptake. They will use questionnaires 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.

Project Timeline

Year 1

Gaining familiarity with the schemes and available data; setting up loan scheme and recruiting participants; training in analytical approaches.

Year 2

Developing and deploying questionnaires; developing models for individual species.

Year 3

Continued modelling for individual species; modelling species diversity; commencing write-up.

Year 3.5

Concluding write-up.

& Skills

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. 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).

References & further reading

See for general information about the MammalWeb project, and for publications relevant to MammalWeb. See for an example of the types of scheme run by the BTO for monitoring urban wildlife.

Further Information

Please contact Dr Philip Stephens ( for further information. 

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