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Accueil du site → Doctorat → États-Unis → 2005 → Effects of resource availability and food preferences on population dynamics and behavior of Ord’s kangaroo rats (Dipodomys ordii)

UNIVERSITY OF NEVADA, RENO (2005)

Effects of resource availability and food preferences on population dynamics and behavior of Ord’s kangaroo rats (Dipodomys ordii)

Auger, Janene

Titre : Effects of resource availability and food preferences on population dynamics and behavior of Ord’s kangaroo rats (Dipodomys ordii)

Auteur : Auger, Janene

Grade : Doctor of Philosophy (PhD) 2005

Université de soutenance : UNIVERSITY OF NEVADA, RENO,

Résumé
Both observational and experimental methods were employed at Arches National Park, Utah (1997–2001) to determine the role of specific food resources in population dynamics, home range use, food selection, and caching behaviors of a heteromyid desert granivore, Ord’s kangaroo rat (Dipodomys ordii). I described the relationship of rodent populations to high supra-annual variation in seed production of blackbrush (Coleogyne ramosissima), a masting shrub, and assessed usage of a vegetationally diverse pipeline corridor by Ord’s kangaroo rats and Plains pocket mice (Perognathus flavescens). Populations peaked during a mast year and declined precipitously in the second fall season after the mast. Kangaroo rats increased their usage of the pipeline corridor through the blackbrush inter-mast interval more than pocket mice. Evidence indicated that competition occurred and kangaroo rats excluded pocket mice from resource-rich environments. Home range sizes were highly variable, and seed mass per unit area in individual home ranges was significantly negatively correlated with home range size in a year of low precipitation and seed production, but not in a year of high precipitation accompanied by a blackbrush masting event. Home range overlap of males with females was not significantly greater than that of females with females. I concluded that food availability is more influential than movements associated with mating in determining home range size. Digestibility of seeds was high (>83%), and in cafeteria trials Ord’s kangaroo rats did not appear to select seed species (n = 6) to maximize intake of water, energy, orprotein. Palatability correlated strongly with rank preference. Indian ricegrass (Oryzopsis hymenoides) was most preferred, featuring high carbohydrates and free water coupled with the absence of secondary compounds. Blackbrush was less preferred, but was nutritionally and ecologically important to kangaroo rats. To minimize pilferage Ord’s kangaroo rats should cache preferred food items farther from the source, more widely spaced, and nearer to defendable areas of the home range than less preferred items. Evidence did not support those predictions. Caches were placed in areas of home range overlap at the same frequency as random placement. Results were consistent with predictions of a rapid-sequestering hypothesis.

Mots clés : BIOLOGY, ECOLOGY ; BIOLOGY, ZOOLOGY

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