An Analysis of Canopy Cover within the Home Ranges of Mexican Wolves (Canis lupus baileyi) Reintroduced into New Mexico and Arizona
Date
2023-08
Authors
Guajardo, Christian A.
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Abstract
Identifying the most important characteristics of a species habitat is vital in understanding its basic ecology and conservation needs. For large predators such as the Mexican wolf, woody vegetation in the form of canopy cover is a habitat characteristic that may play a pivotal role in helping to facilitate many of its basic needs. The Mexican wolf is listed as endangered; it is the most genetically distinct subspecies of gray wolf in North America. I utilized GPS locational data points of collared wolves within the Mexican Wolf Experimental Population Area (MWEPA) of Arizona and New Mexico, and canopy cover data from the National Land Cover Database (NLCD) to determine the extent that Mexican wolves associate with canopy cover. GPS locational data points spanned six years (January 2015 - January 2021). I used ArcGIS to derive three home range types for each of 132 wolves. The home range types consisted of a 95% kernel density estimator (KDE), 60% KDE, and 100-meter buffers (around each individual data point) for each Mexican wolf in my study. For each home range, I used ArcGIS to determine the statistical distribution of canopy cover values (among pixels). In the NLCD, each 30 × 30 m pixel is assigned a canopy cover value in 1% increments. Canopy cover within each home range was compared to two reference regions: a minimum convex polygon (MCP) and an 80-km concave polygon, both created in ArcGIS. For each wolf, each of the three types of home range was tested against the two reference regions using a two-sample Kolmogorov-Smirnov (K-S) test to determine if wolves were utilizing a mix of canopy cover that was different from what was available to them. I found that 126 of 132 wolves had at least one of their six K-S tests to be statistically significant (P < 0.05) indicating that these wolves were using or associating with canopy cover in a non-random way. Of those 126 wolves, 65 of them had all six of their K-S tests to be statically significant. Wolf home ranges tended to have much less area in the 0% canopy coverage category and much more in the ≥ 25% canopy coverage category compared to the reference regions. I also found that the home ranges of wolves tended to mostly consist of areas in the 16 – 30% canopy cover range. These results support the possibility that wolf movement and space use is at least partially influenced by canopy cover wherein wolves tend to avoid areas of little or no canopy cover and spend more time in areas of relatively dense canopy cover. The results of my study may prove to be beneficial to the Mexican wolf recovery program when determining where to provision resources for wolves and what particular areas of a landscape or region to monitor and protect. Furthermore, my study may also aid the USFWS in defining critical habitat for this endangered subspecies and continue the long-term growth and sustainability of the Mexican wolf within the MWEPA, in the event the designation of the population is ever changed.
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Keywords
Mexican wolf, canopy cover, forest canopy coverage, vegetative cover, predator, canids, endangered species, Endangered Species Act, ESA, population surveys, Mexican Wolf Experimental Population Area, Arizona, New Mexico, Biology
Citation
Guajardo, C. A. (2023). An analysis of canopy cover within the home ranges of Mexican wolves (Canis lupus baileyi) reintroduced into New Mexico and Arizona (Unpublished thesis). Texas State University, San Marcos, Texas.