Geology ReportsSearch

Geology topics

James W. Pitman

Publications and source records attributed to James W. Pitman.

2 recordsLinked to original sources

Diurnal habitat selection and survival of elk neonates

Natural selection should favor development of behaviors that increase survival, including juvenile survival. Habitat characteristics (e.g., hiding cover, forage quality and availability), maternal habitat selection, and microhabitat selection by the calf may influence elk ( Cervus canadensis ) calf survival and recruitment. We assessed diurnal microhabitat selection of bed sites by elk calves and calf-rearing areas selected by adult females to determine if these characteristics were associated with calf survival. We radio-tagged 33 elk calves in west-central New Mexico in 2011 and 55 calves in north-central New Mexico in 2012. We tracked calves daily to locate calf bedding sites and collected data on selected physical features and vegetation characteristics at used and paired random sites. The paired differences in these characteristics were then associated with calf fate. At the calf selection scale, for every 1-m difference in the distance to nearest concealment cover, the odds that a site was from a surviving calf increased by 7.8%. Habitat selection by adult females also was associated with calf survival. The odds of a bed site being from a surviving calf increased by 1.9% for every 1% difference in percentage of grass cover. High levels of concealment cover at the bed site were related to calf survival status. When we expanded selection to the adult level, females with surviving calves selected areas with higher grass cover, suggesting adult selection for higher forage availability while still providing high concealment cover for the calf.

Southwestern Naturalist

Post-parturition habitat selection by elk calves and adult female elk in New Mexico

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&ndash;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.

New Mexico