The use of trail cameras has increased our knowledge of the distribution of species. Whether providing evidence of Jaguars in Arizona or black bears as they recolonize familiar haunts in Ohio, the trail camera has proved a tremendously valuable tool to wildlife managers and allowed for participation of citizens un wildlife science projects.
Here at cb’s place, we have 3 trail cameras used to document species richness and as a potential index for species abundance. Ecology has 3 basic types of measures used to determine abundance: 1) census, 2) estimate, and 3)index. A census has the highest level of resolution – it assumes every individual is documented (rarely a safe assumption). A census might suggest there are 128 raccoons in an area. The potential for a trail cam to provide census level data is extremely unlikely – bordering on impossible. An estimate is common in ecology an provides a number of individuals with some measure of error (using our raccoon example – an estimate suggests 114 ± 20 raccoons). Trail cameras have been used to estimate populations, especially in populations where individuals have unique markings (e.g. bobcat or leopard). The measure with the least resolution is the index. In our case, we monitor the number of deer photos per camera night and may compare to last year. We can only infer a relative abundance. There are more (or less or about the same) number of raccoons this year compared to last year.
Here at cb’s place, we have documented deer, fox squirrels, opossum, raccoons, woodduck, woodchuck, skunks and a mink. You can see some of these photos here.