Mexican Wolf Research Articles

Perils of recovering the Mexican wolf outside of its historical range

The Mexican wolf (Canis lupus baileyi) was included in the 1973 Endangered Species Act listing of the gray wolf (C. lupus), but then listed separately as a subspecies in 2015. Early accounts of its range included the Sierra Madre Occidental of Mexico, southeastern Arizona, southwestern New Mexico, and sometimes western Texas, supported by ecological, biogeographic, and morphological data. There have been multiple unsuccessful attempts to revise the original 1982 recovery plan and identify areas suitable for Mexican wolf reintroduction. Despite the fact that 90% of its historical range is in Mexico and widespread suitable habitat exists there, previous draft recovery plans recommended recovery mostly outside of Mexico and well north of the subspecies' historical range. Planning recovery outside historical range of this subspecies is fraught with problems that may compromise, thwart, or impede successful recovery. Dispersal of Mexican wolves northward and continued movements southward by Northwestern wolves (C. l. occidentalis), along with allowing establishment of Mexican wolves north of their historical range before they are recovered, may lead to premature and detrimental intraspecific hybridization. Interbreeding of Northwestern wolves from Canadian sources and Mexican wolves does not represent the historical cline of body size and genetic diversity in the Southwest. If Northwestern wolves come to occupy Mexican wolf recovery areas, these physically larger wolves are likely to dominate smaller Mexican wolves and quickly occupy breeding positions, as will their hybrid offspring. Hybrid population(s) thus derived will not contribute towards recovery because they will significantly threaten integrity of the listed entity. Directing Mexican wolf recovery northward outside historical range threatens the genetic integrity and recovery of the subspecies, is inconsistent with the current 10(j) regulations under the ESA, is unnecessary because large tracts of suitable habitat exist within historical range, is inconsistent with the concepts of restoration ecology, and disregards unique characteristics for which the Mexican wolf remains listed.

Postcranial diversity and recent ecomorphic impoverishment of North American gray wolves.

Recent advances in genomics and palaeontology have begun to unravel the complex evolutionary history of the gray wolf, Canis lupus Still, much of their phenotypic variation across time and space remains to be documented. We examined the limb morphology of the fossil and modern North American gray wolves from the late Quaternary (<ca 70 ka) to better understand their postcranial diversity through time. We found that the late-Pleistocene gray wolves were characterized by short-leggedness on both sides of the Cordilleran-Laurentide ice sheets, and that this trait survived well into the Holocene despite the collapse of Pleistocene megafauna and disappearance of the 'Beringian wolf' from Alaska. By contrast, extant populations in the Midwestern USA and northwestern North America are distinguished by their elongate limbs with long distal segments, which appear to have evolved during the Holocene possibly in response to a new level or type of prey depletion. One of the consequences of recent extirpation of the Plains (Canis lupus nubilus) and Mexican wolves (C. l. baileyi) from much of the USA is an unprecedented loss of postcranial diversity through removal of short-legged forms. Conservation of these wolves is thus critical to restoration of the ecophenotypic diversity and evolutionary potential of gray wolves in North America.

Revisiting revising Mexican wolf historical range: A reply to Hendricks et al.

Hendricks et al. () questioned our clarification of Mexican wolf historical range and our criticism of their expansion proposals far to the north and west. A recent habitat suitability analysis identifies large areas of high quality habitat in Mexico and the latest population viability analysis shows Mexican wolves can be recovered in their historical range. Expanding historical range descriptions based on poorly understood distribution of molecular markers is unnecessary and serves only to impede the recent successful progress to recover the Mexican wolf.

Critics pan wolf plan.

Recovery plan for Mexican wolf promises no new U.S. habitat. States are pleased; some biologists are dismayed.

Defense of an expanded historical range for the Mexican wolf: A comment on Heffelfinger et al.

A recent review titled “Clarifying Historical Range to Aid Recovery of the Mexican Wolf” by Heffelfinger et al. () reviews historical range delineation but misinterprets published studies and encourages the support of antiquated methods to determine appropriate range for this highly endangered subspecies. We respond to Heffelfinger et al. () and argue against a simple typological model, which we maintain is not appropriate for informing conservation or reintroduction decisions, and argue for the use of genome‐wide data and species distribution models when determining historical range for this vagile wolf population.

Attraction-repulsion among top predators following reintroduction efforts

Much of our understanding of the effects top predators play in structuring ecological communities are from studies documenting ecological changes following the recovery or reintroduction of large carnivores. Reintroduced predators, for example, may create unanticipated competition scenarios that influence local carnivore guilds. Here, we tested whether newly released Mexican gray wolves in Chihuahua, Mexico interacted with resident pumas, as a first step in exploring potential competition between the two species. We employed GPS data and novel methods offered by MoveMine 2.0 to quantify attraction-repulsion between individual wolves and pumas during two time periods: the first when wolves were free roaming, and the second when they restricted their movements to an area around their den and rendezvous site to protect and provide for pups. In summary, attraction-repulsion analyses conducted with MoveMine provided meaningful outputs, but we would highlight the importance of fieldwork to interpret interactions and significance values calculated between pairs. We found that high attraction values resulted from mutual attraction between wolves in the same pack, between wolves and one puma they repeatedly harassed, as well as between two pumas that repeatedly exhibited social tolerance for each other. Thus, the analyses offered by MoveMine provided a powerful means of identifying interactions and assessing attraction-repulsion relevant to questions of intra- and interspecific competition, but required intimate knowledge of the species studied and the interactions between them to interpret outputs correctly.

Clarifying historical range to aid recovery of the Mexican wolf

ABSTRACTWe assessed historical, morphological, and genetic information on the range of the Mexican wolf (Canis lupus baileyi) to plan the recovery of this endangered subspecies. Early accounts of its range included the Sierra Madre Occidental, Mexico, and southeastern Arizona, southwestern New Mexico, and sometimes western Texas, USA. Such accounts are supported by ecological, physiographic, and morphological data. Recent suggestions to depict a more extensive northern periphery have been based primarily on a fragmented geographic sampling of genetic markers assumed to be diagnostic at subspecies level. Some of these genetic markers, found in extant Mexican wolves, reportedly also occur in a few individuals far to the north of the range defined in early accounts. Extending the historical range northward would necessitate drawing that line far north of transitions in wolf phenotype, breaks in vegetation associations, barriers to gene flow, and differences in prey base. We review morphologic, genetic, and ecological information to illustrate why such historical range extensions are not supported. The historical distribution of the Mexican wolf likely does not correspond to the detected distribution of certain molecular markers. The historical range of the Mexican wolf should not be altered through the identification of similar habitat in other locations, the distribution of inadequately sampled molecular markers, or by theoretical arguments about movement capacity. Rather, it should respect the original descriptions that were made when the animal was still present on the landscape, and which are concordant with ecological relationships, physiography, morphology, and the principles of population genetics. Clarifying the historical range of the Mexican wolf accurately will be foundational to developing a scientifically defensible recovery plan. © 2017 The Wildlife Society.

Long-term quantification of faecal glucocorticoid metabolite concentrations reveals that Mexican grey wolves may habituate to captivity

Mexican grey wolves are considered the most endangered wolf in the world. The aim of this longitudinal study was to assess the physiological stress level of 24 captive-born wolves confined at four zoos and two parks, by measuring faecal glucocorticoid (fGC) metabolite concentrations in 1005 samples, for 1 week in every season of the year over a 2-year period. Total overall mean fGC concentration of individual scats was 153.83 ± 8.16 standard error mean (SEM) ng/g dry matter (DM). Paired samples from the same individuals showed a decline in fGC levels between years (173.09 ± 12.15 and 135.94 ± 10.93 for 2010 and 2011, respectively; P = 0.02). Significant differences were also observed between reproductive and non-reproductive seasons (116.78 ± 12.48 vs. 173.20 ± 10.50, respectively; P < 0.0001), and between genders (males: 214.53 ± 13.43 vs. females: 121.51 ± 10.03; P < 0.0001). Tukey’s post hoc comparisons showed that elder wolves excreted higher levels than young adults and reproductive adults (P = 0.016). High-social-ranked wolves showed higher (P < 0.0001) fGC levels (202.03 ± 19.94; n = 229) than medium- (175.33 ± 19.94 ng/g DM; n = 214) and low- (162.06 ± 16.15; n = 377) ranked wolves did; however, no correlation was found between social rank and fGC levels. Anthropogenic acute stressors during husbandry procedures a day before sampling resulted in considerable elevations of fGC concentrations above 1270.34 ng/g DM, returning to baseline levels after 2 days. Our results suggest that wolves are becoming habituated to confinement at the zoos; these findings may contribute to a more comprehensive definition of confinement, which has traditionally been perceived as a stressful habitat for wild animals. Using fGC concentrations as an overall physiological state in long-term studies may provide crucial information on the resilience of captive animal populations.

Genetic management and setting recovery goals for Mexican wolves (Canis lupus baileyi) in the wild

Mexican wolf recovery planning has spanned >3 decades, yet federal and state planners have not reached consensus on how to structure recovery efforts with the remaining inbred founder lineages to maximize genetic diversity while balancing many other demographic and social considerations. The US Fish and Wildlife Service and state wildlife agencies are working to draft a revised recovery plan specific to the Mexican wolf that will appropriately incorporate genetic concerns in recovery criteria that can be implemented on a human-dominated landscape. Inbreeding effects, where present in the remaining lineages, are stochastic and unpredictable in a management context. Despite these effects, population growth in Mexican wolves the past 5years rivals the rate observed in Yellowstone wolves during the last decade. While small populations risk extinction via inbreeding depression, there are often larger, more imminent threats of demographics, mortality, or habitat loss that may impact success of recovery efforts. Releasing captive-reared wolves is problematic and often creates conflict in local human communities, but fostering of captive-born wolves into wild wolf packs is a viable means of increasing genetic diversity and decreasing habituated wolf-human conflict. There are many alternative ways to estimate the number of wolves per population needed to recover the Mexican wolf. Efforts should thus be made to provide for sufficient genetic diversity, but not at the expense of more immediate factors that influence successful recovery.

Whole mitochondrial genomes illuminate ancient intercontinental dispersals of grey wolves (Canis lupus)

AbstractAimGrey wolves (Canis lupus) are widespread across the Holarctic. Here, we test the previously proposed hypothesis that extant North American wolves originate from multiple waves of colonization from Asia. We also test the hypothesis that land connections have been important in the evolutionary history of other isolated wolf populations in Japan.LocationHolarctic.MethodsWe analyse 105 previously published and newly obtained complete mitochondrial genomes from a geographically diverse sample of grey wolves and date critical branches in the phylogenetic tree. Phylogeographical hypotheses are tested in an approximate Bayesian computation approach.ResultsWe find that the mitogenomes of all living wolves in North America, including Mexican wolves, most likely derive from a single colonization event from Eurasia that expanded the grey wolf range into North America. This colonization occurred while a land bridge connected Eurasia and North America before the Cordillerian and Laurentide ice sheets fused in the Last Glacial Maximum,c. 23 ka, much more recent than predicted based on the fossil record. Pleistocene land bridges also facilitated the separate colonization of Hokkaido and the southern Japanese islands.Main conclusionsExtant wolf lineages in North America derive from wolves that migrated into North America coincident with the formation of the most recent land bridge with Eurasia. The maternal lineages from earlier Pleistocene American wolves are not represented in living American wolves, indicating that they left no descendants. The timing of colonization of North America, Hokkaido and the southern Japanese islands corresponds to the changes in land connectivity as a consequence of changing sea level.

A noninvasive method to detect Mexican wolves and estimate abundance

Monitoring wolf abundance is important for recovery efforts of Mexican wolves (Canis lupus baileyi) in the Blue Range Wolf Recovery Area in Arizona and New Mexico, USA. Although radiotelemetry has been a reliable method, collaring and tracking wolves in an expanding population will be prohibitively expensive and alternative methods to estimate abundance will become necessary. We applied 10 canid microsatellite loci to 235 Mexican wolf samples, 48 coyote (C. latrans) samples, and 14 domestic dog (C. lupus familiaris) samples to identify alleles that provide reliable separation of these species. We then evaluated an approach for prescreening, noninvasively collected DNA obtained from fecal samples to identify Mexican wolves. We generated complete genotypes for only those samples identified as probable Mexican wolves. We used these genotypes to estimate mark–recapture population estimates of Mexican wolves and compared these to known numbers of wolves in the study area. We collected fecal samples during 3 sampling periods in 2007–2008 and used Huggins-type mark–recapture models to estimate Mexican wolf abundance. We were able to generate abundance estimates with 95% confidence for 2 of 3 sampling periods. We estimated abundance to be 10 (95% CI = 6–34) during one sampling period when the known abundance was 10 and we estimated abundance to be 9 (95% CI = 6–30) during the other sampling period when the known abundance was 10. The application of this noninvasive method to estimate Mexican wolf abundance provides an alternative monitoring tool that could be useful for long-term monitoring of this and other recovering populations. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

Variations in the locomotor activity of the Mexican wolf (Canis lupus baileyi) respect to moon periodicity: a study in an outdoor enclosure

It is assumed that the response of the regulatory system of mammal activity depends on the changes in light intensity throughout the 24-h cycle. The aim of this study was to determine whether the moon luminosity cycle exerts an effect on the locomotor activity of the Mexican wolf (C. lupus baileyi). Data collection was carried out with the actimetry, of 11 individuals were analyzed using ANOVA to determine the effect of the lunar cycle. Significant differences were encountered between moon phases (p = 0.001), with a decrement of activity during new and full moon. However, effects were dependent also on the age of the individuals and the daylight period. On the other hand, it is a possible regulation of the activity pattern by the effect of lunar periodicity. This periodicity needs a more detailed examination to determine its adaptive function.

Re-defining historical geographic range in species with sparse records: Implications for the Mexican wolf reintroduction program

Reintroduction is often the only remaining option for recovery of extirpated species. According to the U.S. Endangered Species Act, species should be reintroduced to suitable habitats within their probable historical range. However, accurately defining historical range often proves difficult, especially for taxa with limited historical information, and may represent a significant impediment for successful recovery. Here, we combine ecological modeling methods with morphometric and phylogenetic data from museum specimens to define a more biologically realistic historical distribution. We apply this approach to the Mexican wolf (Canis lupus baileyi), the most endangered and genetically distinct wolf subspecies in the New World. Our model substantially increases the potential geographic range of the Mexican wolf to include areas in southern California and Baja California, areas not previously recognized as part of the historical range. Motivated by this prediction, we reanalyzed morphometric data and genetically typed the only historical specimen known from southern California, which was previously assigned to another wolf subspecies. We found that the specimen was in fact of pure Mexican wolf ancestry and fell within our predicted range for this subspecies. Our findings provide an impetus for reconsidering reintroduction sites for the Mexican wolf and highlight how critical taxonomic assignment can be to reintroduction programs and species recovery. Re-analysis of potential range in other extirpated species that have ranges defined by antiquated taxonomic approaches used on a limited number of specimens could enhance the success of future reintroduction programs and restore historical processes such as admixture that can preserve the adaptive legacy of endangered species.

When shooting a coyote kills a wolf: Mistaken identity or misguided management?

The recovery of wolf populations in the United States (U.S.) is hampered by ongoing human-wolf conflicts. In particular, the illegal killing of grey wolves (Canis lupus), red wolves (Canis rufus), and Mexican wolves (Canis lupus baileyi) protected under the U.S. Endangered Species Act has contributed to relatively high mortality rates in some areas. One issue is that wolves are often mistaken as coyotes (Canis latrans) and illegally shot by hunters. To minimise cases of mistaken identity, stricter regulation of coyote hunting is being adopted in some areas where endangered wolves exist. Here we argue that such management should be adopted more widely, and especially in areas where wolves are at low densities or recolonising new areas. Such a proposal may face opposition, particularly where coyote hunting is common, or where coyotes are perceived as a threat to human enterprises such as livestock ranching. Appropriate education and training is needed to ensure that the public is aware that (i) wolves and coyotes are difficult to distinguish from a distance and (ii) coyotes are far too resilient to be affected by most periodic eradication programs, let alone from derbies or recreational hunting. We conclude that recreational hunting of coyotes could restrict wolf recolonisation while providing little benefit to animal agriculture. Consideration of new management strategies is therefore required to assist with wolf restoration efforts and to minimise ongoing human-wildlife conflicts.

U.S. creates more roaming room for Mexican wolves, but green groups say they’ll sue

U.S. creates more roaming room for Mexican wolves, but green groups say they’ll sue

Polyphyletic ancestry of historic gray wolves inhabiting U.S. Pacific states

Given the recent re-colonization of gray wolves (Canis lupus) to the Pacific northwest, USA, and subsequent migration into northern California, understanding how well natural migration has restored historic diversity can inform management decisions. In this study, we report the mitochondrial DNA control region haplotypes of nine museum specimens that curators identified as C. lupus from Oregon, Nevada, and California. Among the nine samples currently available for genetic analysis of historic genetic diversity of C. l. spp. in the U.S. Pacific states, we found six previously described haplotypes including two domestic dog (C. l. familiaris) haplotypes. Notably, we present the first evidence of Mexican wolf (C. l. baileyi) ancestry in southern California while the northern Californian specimen, as well as one individual from Nevada, present a haplotype common to wolves from the historic American West and extant Canadian wolf populations. Finally, the three Oregon specimens shared a haplotype that is only observed in extant wolves from coastal British Columbia (the “coastal rainforest” wolf ecotype), indicating that the historical range of this haplotype reached as far south as southwestern Oregon. In conclusion, our results indicate that the genetic composition of historic wolf populations in the Pacific northwest and southwest states was polyphyletic and included wolves that share maternal ancestry with current populations from adjacent regions. These findings, in addition with future nuclear analyses, reveal more accurate historic range delimitations, which is critical information when designing appropriate management plans for wolves naturally re-colonizing the U.S. Pacific northwest and southwest regions.

A GIS-based approach to documenting large canid damage to bones

Experimental studies of modern carnivore tooth marking patterns are integral to understanding the nature of carnivore involvement in archeological bone assemblages. However, modern bone damage data for most carnivore taxa are limited. This is particularly true for canids. This study presents bone damage data collected from feeding experiments conducted with Mexican Gray Wolves (Canis lupus baileyi) and Red Wolves (Canis rufus). This is the largest experimental assemblage reported for canids to date. The image-analysis GIS approach described by Marean et al. (2001) is expanded on here and used to document bone preservation and tooth mark distribution for the first time in a carnivore-modified bone assemblage. Further, we introduce the use of the ArcGIS Spatial Analyst to identify significant concentrations of bone modifications. Results show that the distribution of tooth pits varies considerably across elements as well as across different portions of the same element, and that significant clusters of tooth pits occur on all long bones. We suggest that with a large enough sample, the GIS Spatial Analyst can be a useful tool for analyzing the distribution of bone modifications with greater resolution than previous methods. This method facilitates comparisons between experimental and fossil assemblages which may aid in identifying the timing of access to carcasses by carnivores involved in modifying fossil assemblages. Finally, the use of this rigorous methodology is a step toward increasing standardization in methods of taphonomic analysis.

Firepower

When, on September 18, 1909, Aldo Leopold shot a she-wolf and then watched the “fierce green fire” in her dying eyes, he found a story that he subsequently reworked into a foundational parable for humanity's relationship with nature. A century later, in June 2011, a wildfire boiled out of the Bear Wallow Wilderness on the Apache National Forest and burned over that hallowed landscape. The fire spoke to an odd entangling of symbols. The Apache National Forest was, during Leopold's time as a ranger, a progressive emblem of state-sponsored conservation. The Bear Wallow Wilderness was a sterling token of a postwar environmentalism that emphasized nonanthropogenic values. Between them, and a bit to the east, and no doubt inspired by Leopold's morality tale, Mexican gray wolves had been reintroduced in 1998. The Wallow fire burned over all three sites. At 548,000 acres, it was the largest forest fire in Arizona's recorded history.

Economic Analysis of Indemnity Payments for Wolf Depredation on Cattle in a Wolf Reintroduction Area

Mexican gray wolves were reintroduced into New Mexico and Arizona in 1998. When wolves kill a producing cow, ranchers in the region are eligible to receive an indemnity payment equal to the market value of the lost animal. We developed a model that allows estimation of the present value of the revenue stream that a cow or herd provides and find that if a producing cow is killed, the decrease in the present value of the rancher’s revenue stream is about $1,230. Mean indemnity payments are currently $1,000, implying ranchers are not being sufficiently compensated.

Presencia de doble estro anual en una hembra de lobo mexicano (Canis lupus baileyi) en cautiverio

Resumen As in most of the wolf subspecies, sexual behavior in Mexican wolf is shown in late winter once a year. Reproductive cycle in female wolves includes seasonality and monoestrum, with a long anestrus period. Estrogens and progesterone are responsible for estrus appearance and presence of both seems to be necessary for the full stimulation of sexual behavior in female wolves. In previous studies we made quantification of fecal estrogens and progesterone to several couples of Mexican wolves in captivity, in all the cases peaks on both hormones are correlated with reproductive behavior and shown in winter. Lately, another couple hosted in Aragon Zoo, Mexico City, shown, on in an unexpected way, sexual behavior during August in addition to the normal one in February; then we performed a sexual hormones analysis since this last periods in fecal samples. Results show a significant rise on female sexual steroid hormones concentrations in both, winter and summer. Female was checked for clinical and physical disorders, finding no evidence of pathologies. Pedigree was reviewed looking for possible hybridization, but only a pure wolf lineage was found, environmental factors were also studied providing no evidence that could explain such hormones concentrations. This is first report in summer of estrus behavior in Mexican wolf.