Cameras, Coyotes, and the Assumption of Equal Detectability

• Published in: The Journal of wildlife management Vol. 71; no. 5; pp. 1682 - 1689
• Main Authors: LARRUCEA, EVELINE SÉQUIN, BRUSSARD, PETER F, JAEGER, MICHAEL M, BARRETT, REGINALD H
• Format: Journal Article
• Language: English
• Published: Oxford, UK The Wildlife Society 01.07.2007; Blackwell Publishing Ltd
• Subjects: activity pattern; Animal behavior; animal identification; Animals; camera; Cameras; Canis latrans; census; circadian rhythm; collars; coyote; detection; Dispersal; Females; Influence; infrared-triggered; Organized crime; Photography; Population estimates; radio frequency identification; sampling; seasonal variation; Sequins; spatial variation; Techniques and Technology Articles; Techniques and Technology s; temporal variation; wild animals; Wildlife; Wildlife ecology; Wildlife habitats; Wildlife management; Wildlife studies; California
• ISSN: 0022-541X; 1937-2817
• DOI: 10.2193/2006-407

Remote cameras are an increasingly important tool in management and wildlife studies. However, we often do not know if they provide an unbiased sample of populations. Using a marked, radiocollared population of coyotes (Canis latrans) of known social status, we evaluated the influence of temporal (daily and seasonal) and spatial (distance between units, habitat, and proximity to human structures) factors on vulnerability to photo-captures. During 8 unbaited camera sessions of 6 weeks each, we obtained 158 coyote photographs at a photo-capture success rate of 1.6%. We were able to identify not only marked individuals, but also a number of uncollared adults through variation in their pelage. Photo-capture of adults peaked 2 weeks after we established camera stations. Annual success for photographing adult coyotes was greatest during March and April, which corresponded with the dispersal season. The majority of photo-captures occurred at night, and adult photo-captures peaked around midnight, with smaller peaks at dawn and dusk. Rather than reflecting a circadian activity pattern, nighttime captures seemed to reflect when adult coyotes were most vulnerable to photo-capture. Characteristics of camera locations, such as amount of human activity, being on roads versus trails, and habitat type, also influenced the number of photo-captures. We conclude that remote cameras do not always provide an unbiased sample of populations and that animal behavior is important to consider when using these systems. Researchers using camera techniques need to carefully consider when, where, and how cameras are placed to reduce this bias.