BiodiversityWorks has been participating in the nationwide mammal survey Snapshot USA since 2021. In the four years since then, we've developed an excellent rhythm. The project is well known and popular in the schools that help us with the project; we have the necessary equipment to deploy, protect, and monitor three camera grids on the island; and we have a group of motivated volunteers who help us manage the large amounts of data inherent in camera trapping projects. All of this is to say we laid a strong foundation for this project and are well situated to continue this survey in the coming years.
However, we are careful that this rhythm does not turn into a routine. As with all our projects, we want to keep up with the best science and data collection protocols. And as new research comes out that suggests new best monitoring practices, we make sure to incorporate these findings into our research projects. For example, at the annual online pre-season meeting of Snapshot USA participants, Bridgit Rooney, the scientist coordinating the Snapshot USA project, announced that analysis of the first five years of data indicated the minimum number of camera locations and camera nights in their protocols was not enough and should increase to ensure we capture all mammal species these deployments can capture. In plotting the number of species detected against the number of camera days deployed, the data showed, across all regions, camera grids that collect at least 600 camera-nights worth of data document more mammalian species than grids that only capture the project minimum of 400 camera-nights (Figure 1), indicating those with fewer camera nights may be missing species.
Figure 1. The Smithsonian found that across most physiographic regions more mammals were detected when camera grids were deployed for 600 camera nights rather than the previous project minimum of 400 camera nights. From Rooney et al. 2025
These findings led to the recommendation that participating groups increase the minimum number of camera locations from eight to 15 to increase camera nights and species detected. In 2024 the three grids we deployed each collected 500-600 camera nights of data from 12 camera locations. To increase camera-nights, we simply deployed all our cameras earlier in the survey window this year, and we are already well on our way to collecting the new suggested minimum of 600 camera nights. But, shifting 3 cameras to new locations part way through data collection could also increase our chances of detecting more species of mammals.
To determine where we should add new camera locations in order to reach the new minimum of 15 locations in each array of cameras, particularly in our two grids surveying anthropogenic habitat in Edgartown and Oak Bluffs, we went looking for best camera trapping practices in urban landscapes. In our search, we found this publication in the Journal of Urban Ecology, which was co-authored by two of the directors of Snapshot USA. In this paper, the authors point out the importance of sampling a diversity of green spaces in developed areas to avoid bias in urban sampling. We were already sampling public cemetaries and parks and a couple of yards. So, with these findings in mind, we reached out to several friends of BiodiversityWorks who live in Edgartown and Oak Bluffs and got permission to create new camera locations in their yards.
It will be exciting to see what mammals we capture following these new camera trapping best practices.
A raccoon captured during snapshot 2024 in BiodiversityWorks Assistant Director Liz Olson's Yard
An eastern gray squirrel captured during snapshot 2024 in BiodiversityWorks Assistant Director Liz Olson's Yard
Herrera, D.J., S.M. Moore, D.T. Tyler Flockhart, W.J. McShea, M.V. Cove. (2021). Thinking outside the park: recommendations for camera trapping mammal communities in the urban matrix, Journal of Urban Ecology, 7(1), juaa036, https://doi.org/10.1093/jue/juaa036
Rooney, B., Kays, R., Cove, M. V., Jensen, A., Goldstein, B. R., Pate, C., ... & Lesmeister, D. B. (2025). SNAPSHOT USA 2019–2023: The First Five Years of Data From a Coordinated Camera Trap Survey of the United States. Global Ecology and Biogeography, 34(1), e13941.
