Changes in Kit Fox Defecation Patterns During the Reproductive Season: Implications for Noninvasive Surveys

Abstract

Noninvasive survey methods based on analyzing DNA extracted from feces can be useful for carnivores that are difficult to study by other methods. Changes in fecal deposition patterns associated with reproduction in kit foxes (Vulpes macrotis) might affect results of such surveys. We used a trained dog to collect fresh scats on 2‐km transects in the home ranges of 11 radiocollared female kit foxes in January, February, and March 2008 and determined sex of the individual that deposited the scats by amplifying the zinc finger protein gene. Female foxes give birth in mid‐February to mid‐March. We found a similar number of scats each month. In January, the sex ratio of the scats was not different from the expected 1:1. However, in February there were almost 2 male scats for every female scat and in March there were >8 male scats for every female scat. Comparing March to January, there were more male scats on all 11 transects and fewer female scats on 10 of 11 transects. Around the time pups are born, both sexes appear to show changes in fecal deposition patterns that make it easier to find male scats and harder to find female scats. Effects of these changes on survey results will vary depending on the purpose and design of the survey. Surveys to determine distribution and relative abundance would probably not be negatively affected by these changes. However, if surveys to estimate abundance are conducted during the reproductive season, they could result in an underestimate of population size unless the increased heterogeneity in scat detectability is taken into account.

Finding a Fox: An Evaluation of Survey Methods to Estimate Abundance of a Small Desert Carnivore

“…But if multiple species are of concern, it would be possible to use this technique to efficiently identify multiple target species [19] with proper training. DNA analysis could also be used for verification of species and/or determining species abundance [4], [14], [17], [19], [51]. The use of scat detection dogs may increase detections rates [19], [51] and if the dog is trained to detect a particular species, it could assist in the proper identification of the target species [19].…”

“…The risk of misidentification was highest during the pup-rearing season when juvenile coyotes and red foxes have the highest overlap in scat diameter with kit foxes. Before conducting scat deposition surveys, one should be aware of seasonal defecation patterns and related concerns when estimating site occurrence or abundance [17].…”

“…Current methods used for surveying kit foxes and their close relative the swift fox ( V. velox ), include capture-recapture [2], [13]–[17], spotlight surveys [2], [13]–[15], [18], scent station surveys [2], [13]–[15], scat deposition transects with and without scat detection dogs [2], [14], [15], [17], [19], track counts [14], activity index [15], and howling response [14]. Generally these methods have been evaluated in study areas with a relatively high fox density.…”

Sex Determination of Sika Deer (Cervus nippon yesoensis) Using Nested PCR from Feces Collected in the Field

“…As for factors related to the DNA condition, climate including temperature, humidity and rainfall, as well as diet or elapsed time from defecation are suggested [3,17,24]. For feces in a low DNA condition, repeating fecal DNA extraction or PCR amplification will be needed due to allelic dropout and false alleles resulting from DNA degradation [2,11,25]. Therefore, a pilot study for determining a suitable strategy was recommended.…”

“…In this situation, fecal samples that can be collected noninvasively are simply counted instead of biomaterials and studies using fecal samples have been conducted in many species [2,5,11,23,25,30]. To use fecal samples for further analysis beyond genotyping, sex information will be essential.…”