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Accueil du site → Master → Etats Unis → 1981 → Seed utilization by heteromyids in a Chihuahuan desert community

University of Texas at El Paso (1981)

Seed utilization by heteromyids in a Chihuahuan desert community

Cordova, Frank Glen

Titre : Seed utilization by heteromyids in a Chihuahuan desert community

Auteur : Cordova, Frank Glen,

Université de soutenance : University of Texas at El Paso

Grade : Master of Science 1981

Seasonal diets of three desert rodents : Dipodomys ordii, D. merriami, and Perognathus penicillatus were analyzed and compared in terms of seed energy content, seed weight, and heteromyid foraging strategies to determine methods of food resource allocation in a mesquite hummock community of south-central New Mexico. Items ingested and their relative frequencies were determined by microscopic examination of fecal pellet contents. Seeds, comprising the primary food of all species, were analyzed for availability, weight, and energy content. It was found that seeds from six forb and four shrub species commonly were used as they became available, but unclear species-specific preferences and microhabitat use determined the relative quantities used by different heteromyids. The rodents were found to specialize on certain food items during mid-summer when resource levels were low. Average dietary overlap for heteromyids in July and August was < = 0.468. During the late summer-early fall and late fall months resource allocation became less important and more generalized patterns of feeding and foraging were evident. Average dietary overlap in September and October was * = 0.623 and « <= 0.594 in November and December. No significant rank-order correlations were shown between seed energy content and diet. Use of seeds of intermediate or low energy levels occurred when such seeds were abundant. In September and October seeds used by D. merriami and seed weights were negatively correlated (r = -0.9000, p < 0.05). This correlation appears to be a result of preference for open, interdunal microhabitat where a large number of small forb seeds occurred. R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. Perognathus penicillatus used seeds from shrubby plants that provided cover. The diet of D. ordii was positively correlated with high seed densities on the study plot in November and December (r = 0.7394, p < 0.05). Dipodomys ordii. which probably was intermediate in cover requirements, ate seeds that occurred both in the open, interdunal microhabitat and in the densely vegetated, dunal microhabitat during this period.

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Page publiée le 27 août 2010, mise à jour le 11 décembre 2018