Garrison K.R.,New Mexico State University |
Cain J.W.,U.S. Geological Survey |
Rominger E.M.,Wildlife Way |
Goldstein E.J.,Wildlife Way
Journal of Wildlife Management | Year: 2016
Foraging behavior affects animal fitness and is largely dictated by the resources available to an animal. Understanding factors that affect forage resources is important for conservation and management of wildlife. Cattle sympatry is proposed to limit desert bighorn population performance, but few studies have quantified the effect of cattle foraging on bighorn forage resources or foraging behavior by desert bighorn. We estimated forage biomass for desert bighorn sheep in 2 mountain ranges: the cattle-grazed Caballo Mountains and the ungrazed San Andres Mountains, New Mexico. We recorded foraging bout efficiency of adult females by recording feeding time/step while foraging, and activity budgets of 3 age-sex classes (i.e., adult males, adult females, yearlings). We also estimated forage biomass at sites where bighorn were observed foraging. We expected lower forage biomass in the cattle-grazed Caballo range than in the ungrazed San Andres range and lower biomass at cattle-accessible versus inaccessible areas within the Caballo range. We predicted bighorn would be less efficient foragers in the Caballo range. Groundcover forage biomass was low in both ranges throughout the study (Jun 2012-Nov 2013). Browse biomass, however, was 4.7 times lower in the Caballo range versus the San Andres range. Bighorn in the Caballo range exhibited greater overall daily travel time, presumably to locate areas of higher forage abundance. By selecting areas with greater forage abundance, adult females in the Caballo range exhibited foraging bout efficiency similar to their San Andres counterparts but lower overall daily browsing time. We did not find a significant reduction in forage biomass at cattle-accessible areas in the Caballo range. Only the most rugged areas in the Caballo range had abundant forage, potentially a result of intensive historical livestock use in less rugged areas. Forage conditions in the Caballo range apparently force bighorn to increase foraging effort by feeding only in areas where adequate forage remains. © 2015 The Wildlife Society.
Lien L.A.,New Mexico State University |
Millsap B.A.,New Mexico State University |
Millsap B.A.,U.S. Fish and Wildlife Service |
Madden K.,Wildlife Way |
Roemer G.W.,New Mexico State University
Ibis | Year: 2015
Life history theory predicts that individuals should maximize lifetime reproductive success (LRS) by breeding as soon as they reach sexual maturity, yet many species delay breeding, either because there are insufficient available mates or breeding sites, or because delayed breeding yields higher LRS. Accipitriform species, such as Cooper's Hawk Accipiter cooperii, exhibit both delayed breeding and delayed plumage maturation. However, in certain circumstances, first-year females in non-definitive plumage do breed and apparently compete with older females for high-quality breeding territories. We predicted that these young females are at a competitive disadvantage compared with older females and that older females would have both higher reproductive success and be able to acquire higher quality nesting territories. We conducted brood counts and measured prey delivery rates by male Cooper's Hawks in an expanding urban population located in Albuquerque, New Mexico (USA), to assess our prediction. We found that older females had higher reproductive success, fledging 1.6 more offspring than younger females, and that they occupied territories where males provisioned at higher rates of 0.37 more prey items per 2-h period. Our results showed that older females fared better than first-year females but it is unclear if this is the result of passive or active competition. Older females initiated nesting 14.3 days sooner than first-year females and thus may have filled vacant, high-quality territories before first-year females began seeking mates. Additionally, first-year females were never observed persistently to confront older females for breeding territories, but they did actively compete against each other. First-year females may defer to older females who, in a direct competitive interaction, would be most likely to prevail. Thus, delayed plumage maturation in Cooper's Hawks may serve to focus competition for nesting territories within age classes. © 2015 British Ornithologists' Union.
Pitman J.W.,New Mexico State University |
Cain Iii J.W.,U.S. Geological Survey |
Liley S.G.,Wildlife Way |
Gould W.R.,New Mexico State University |
And 2 more authors.
Journal of Wildlife Management | Year: 2014
Neonatal survival and juvenile recruitment are crucial to maintaining viable elk (Cervus elaphus) populations. Neonate survival is known to be influenced by many factors, including bed-site selection. Although neonates select the actual bed-site location, they must do so within the larger calf-rearing area selected by the mother. As calves age, habitat selection should change to meet the changing needs of the growing calf. Our main objectives were to characterize habitat selection at 2 spatial scales and in areas with different predator assemblages in New Mexico. We evaluated bed-site selection by calves and calf-rearing area selection by adult females. We captured 108 elk calves by hand and fitted them with ear tag transmitters in two areas in New Mexico: the Valle Vidal and Blue Range Wolf Recovery Area. In both study areas, we found that concealing cover structure and distance to that cover influenced bed-site selection of young calves (i.e., <2 weeks of age). Older calves (i.e., 3-10 weeks of age) still selected areas in relation to distance to cover, but also preferred areas with higher visibility. At the larger spatial scale of calf-rearing habitat selection by the adult female, concealing cover (e.g., rocks, shrubs, and logs) and other variables important to the hiding calves were still in the most supported models, but selection was also influenced by forage availability and indices of forage quality. Studies that seek to obtain insight into microhabitat selection of ungulate neonates should consider selection by the neonate and selection by the adult female, changes in selection as neonates age, and potential selection differences in areas of differing predation risk. By considering these influences together and at multiple scales, studies can achieve a broader understanding of neonatal ungulate habitat requirements. Published 2014. This article is a U.S. Government work and is in the public domain in the USA. © Published 2014. This article is a U.S. Government work and is in the public domain in the USA.
Witt C.C.,University of New Mexico |
Graus M.S.,University of New Mexico |
Walker H.A.,Wildlife Way
Western Birds | Year: 2010
A small alcid of uncertain identity was salvaged from a brine pool associated with a potash mine in Eddy County, New Mexico, on 12 July 2009. The carcass was brought to the Museum of Southwestern Biology, prepared as a specimen, and tentatively identified as a Long-billed Murrelet (Brachyramphus perdix), but identification based on measurements and plumage characteristics was not conclusive. DNA sequence from the mitochondrial gene cytochrome-b confirmed the specific identity but revealed a previously unrecognized mitochondrial variant of the Longbilled Murrelet. This specimen provides the first documentation of the Long-billed Murrelet in New Mexico, a record that was anticipated from the species' established pattern of vagrancy across North America. This vagrant's novel mitochondrial DNA haplotype reveals previously undescribed population genetic structure within the Long-billed Murrelet.