Search

Abstract Estimating wildlife abundance, particularly for rare and elusive species, is challenging because of time, cost, and methodological constraints. The Mexican wolf (Canis lupus baileyi), a federally‐listed endangered subspecies of gray wolf, is currently monitored using ground and aerial methods to obtain a minimum known population count. As the Mexican wolf population has grown and expanded, the time and cost required to monitor the subspecies has increased. We investigated the efficacy of camera trapping for estimating Mexican wolf abundance by comparing the accuracy, precision, and cost of camera trapping to those obtained with current monitoring techniques. Between 1 November 2019 and 31 July 2020, we collected 13,317 photos of wolves from 124 camera traps in Arizona where Mexican wolves were known to occur, excluding tribal lands. We used a spatial mark‐resight analysis to estimate abundance for both winter (November 2019 through February 2020) and summer (April through July 2020) seasons, with and without the assistance of global positioning system (GPS) telemetry data to identify individual wolves. Combined with GPS data, camera trapping provided a summer abundance estimate (N ˆ = 50, 95% CI = 37–64) that was 14% lower than the 2019 minimum known population count (N = 59), but included the minimum known population count in the 95% confidence interval. The summer no telemetry abundance estimate was 27% below the minimum known population count (N ˆ = 43, 95% CI = 30–56). During winter, abundance estimates obtained from camera trapping (no telemetry: N ˆ = 33, 95% CI = 15–52; telemetry: N ˆ = 45, 95% CI = 28–62), were much lower than the 2019 Mexican wolf minimum known population count (winter: N = 62), but included the minimum known population count in the 95% confidence interval for the winter telemetry dataset. A cost comparison indicated that the first‐year camera trapping equipment expenses were 1.7 times the equipment cost of the current method and that camera trapping equipment expenses in subsequent years were equivalent to the equipment cost of the current method, and required at least 1.4 times the labor hours. We provide recommendations to potentially improve Mexican wolf abundance estimates and minimize camera trapping expenses. The results of our project may help managers make appropriate decisions for their population monitoring needs, while considering budget, staffing capabilities, precision, and accuracy.

Systematic diet studies of Mexican gray wolves (Canis lupus baileyi) were not conducted before wolves were extirpated by the late 1960s from the southwestern United States. We collected carnivore scats (n = 1,692) from the Apache and Gila national forests in Arizona and New Mexico, USA, from April 1998 through October 2001 and identified scats to species using traditional field methods, of which 251 were identified as Mexican wolf scats. We found the diet consisted of large-sized food items (92.8% percent frequency of occurrence [PFO]), primarily elk (Cervus elaphus) adults (36.6% PFO) and calves (36.2% PFO). Biomass calculations indicated that Mexican wolves consumed 414 kg of prey as represented by the scats, with elk representing 76.7% of the biomass. When comparing PFO with percent biomass, PFO calculations may have underrepresented larger food items and percent biomass may have overrepresented smaller food items. We compared the diet composition of Mexican wolf scats (n = 251) to the diets reported in previous North American gray wolf (C. lupus) studies (n = 7). The high proportion of elk in Mexican wolf diets in our study area may reflect the low-density, early colonizing stage of the wolf population and elk probably being the most numerous ungulate in our study area. Our results suggested that free-ranging Mexican wolves consumed a higher proportion of large-sized prey than other North American gray wolves. Our results provide baseline diet information for a newly reestablished wolf population. [ABSTRACT FROM AUTHOR]

Mexican gray wolves (Canis lupus baileyi) are the smallest subspecies of North American gray wolves (Canis lupus), and identification of Mexican wolf scats could be confused with those of sympatric coyotes (Canis latrans). We used DNA analysis (molecular scatology) to differentiate scats (n=203) of free-ranging Mexican gray wolves and coyotes and compared the results to traditional field methods (i.e., diameter, location, and sign) and odor used for identifying scats of the 2 species. We then used the scats whose species identifications were confirmed with DNA analysis to evaluate discriminant analysis for classifying scats using 3 measurements--diameter, mass, and length. Forty-nine (24%) of the field-collected scats (n=203) tested provided amplifiable DNA and were determined to comprise 28 scats deposited by Mexican wolves and 21 deposited by coyotes. Scats identified with DNA analysis to the 2 species had a 79% diameter overlap (Mexican wolf 16.3-35.8 mm; coyote 17.4-27.8 mm), and scats ≥28 mm in diameter were Mexican wolf scats. There was a significant difference (t=-2.28; P<0.05) between diameter means for the 2 species (Mexican wolf x=26.0 mm; coyote x=22.8 mm). Of 45 scats that would have been field-identified as deposited by Mexican wolves based on location and odor criteria, DNA analysis indicated that 19 (42%) were deposited by coyotes; of 41 scats that would have been field-identified as deposited by coyotes based on diameter <30 mm criterion, 20 (49%) were deposited by Mexican wolves. Halfpenny's (1986) suggested diameter criterion for field identification of scats identified 3 of the scats as gray (Urocyon cinereoargenteus) or red fox (Vulpes vulpes; 0% correct), 24 as coyote (62% correct), and 20 as Mexican wolf (75% correct). Discriminant analysis indicated that diameter and mass of scats offered the best results for accurately classifying coyote scats (86%) but provided relatively low accuracy for classifying Mexican wolf scats (65%). O... [ABSTRACT FROM AUTHOR]

Provides an overview of the program to restore Mexican wolves to suitable habitat within its historical range in the United States. Taxonomy and historic range of Mexican wolves; Natural life history of the Mexican wolf; Population and legal status in the wild; Information on the Mexican Wolf Recovery Team; Reestablishment plan and description of recovery areas.