A comparison of methods for monitoring kit foxes at den sites

Monitoring mammalian carnivores at den sites with human observers to document behavior, fecundity, litter size, and natal survival is commonplace when compared with monitoring den sites with cameras. However, no published studies exist comparing the effectiveness of human observers versus cameras in a quantitative manner. Obtaining complete and reliable counts of adult and pup kit foxes (Vulpes macrotis) can be crucial for estimating population parameters and life-history traits. In the summers of 2010 and 2011, we made weekly counts of adult and pup kit foxes at active den sites using 2 methods: 1) an observer equipped with spotting scope and/or binoculars and 2) a remote infrared motion-sensitive camera. We accumulated 71 and 29 counts at active den sites, respectively. The median number of adults observed at den sites with a camera and observer differed and were 2 adults versus 1 adult, respectively. Similarly, the median number of pups observed at den sites with a remote camera versus an observer differed and was 2 pups versus 1 pup, respectively. We observed these differences despite the similar effort required to manage cameras and conduct observations. We recommend future surveys aimed at ascertaining more reliable counts of kit foxes and similar species at den sites use a survey methodology employing remote cameras or video over a multi-day period.