Cooperative Fish and Wildlife Research Units Program: Michigan
Education, Research and Technical Assistance for Managing Our Natural Resources

Shamon, Hila. Et Al. 2024. Snapshot USA 2021: A third coordinated national camera trap survey of the United States - first trends.


SNAPSHOT USA is a multi-contributor camera trap survey designed to survey mammals across the United States. The growing Snapshot dataset is useful for tracking wildlife populations responses to changes in land use, land cover, and climate across spatial and temporal scales. Here we present the SNAPSHOT USA 2021 dataset, the third national camera trap survey across the U.S. Data were collected across 109 camera trap arrays and consists of 1715 camera sites, 1849 camera deployments, the effort equaled 73,959 camera trap nights, and resulted in 172,957 observations of free-ranging mammals, birds, and humans. As an example of the potential uses, we analyze all 3 years of survey data to examine the proportion of change in occupancy of two sympatric common carnivores and two sympatric common ungulates: red fox (Vulpes vulpes), coyote (Canis latrans), mule deer (Odocoileus hemionus), and white-tailed deer (Odocoileus virginianus). We considered annual arrays to be comparable if separated by < 10 km and represented similar habitat. White-tailed deer occupancy remained stable across all years (mean proportion 2021/2019: 1.03 ± 0.38 SD). Occupancy proportions (mean proportion 2021/2019) between years for the other species appear stable for mule deer (0.93 ± 0.8 SD), increasing for coyote (1.34 ± 0.56 SD), and decreasing for red fox (0.74 ± 0.79 SD), but in each case the variability between regions precludes significance at the national level. Data collected across years can detect changes in species occurrence, but assessment at the national level require examination of occurrence in relation to land cover and climate gradients.