Patch selection in heterogeneous environments : a hierarchical view of foraging decisions /
I investigated how spatial and temporal variation in foraging rewards affected patch use of animals in heterogeneous environments. Using artificial patches (seed trays), I measured foraging rates Of groups of 1-4 bobwhites (Colinus to examine relationships between patch depletion, satiation and for...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1995.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=742145141&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | I investigated how spatial and temporal variation in foraging rewards affected patch use of animals in heterogeneous environments. Using artificial patches (seed trays), I measured foraging rates Of groups of 1-4 bobwhites (Colinus to examine relationships between patch depletion, satiation and foraging rewards. Mean encounter rate of birds declined with increasing group size, while handling time remained constant. Groups size effects on individual harvest rates were nonlinear: functional response curves changed markedly as group size increased to > 3 birds. In a second experiment, I used captive bobwhites in field enclosures containing seed trays and 3 levels of supplementation to investigate how foraging decisions are affected by habitat quality. Supplementation caused birds to abandon seed trays at higher giving-up densities (GUD) than in unsupplemented enclosures. In a third experiment, I measured GUDs in seed trays with different availability of structural cover. Birds used patches in cover more intensively than those without cover, indicating that cover may have reduced foraging costs due to predation. Two experiments with captive white-tailed deer ( docoileus examined the spatial and behavioral response of deer to spatial heterogeneity in foraging rewards. In the first experiment, patch depletion in differently grazed field enclosures caused deer to select patches offering highest rewards (CP intake) regardless of grazing history and available biomass of the patch. In the second experiment, I studied the distribution and patch use of white-tailed deer foraging at 2 continuous input patches offering different reward opportunities. At equilibrium distribution, deer overutilized the poor patch. I tested 4 alternative models explaining over-utflization of poor patches and conclude sampling and information gathering was an essential part of the foraging process. Lastly, I investigated the role of pre-harvest information, reward distribution and patch spacing in foraging decisions of captive bobwhites. Bobwhites appeared to have a distinct spatial radius across which they were capable of selectively exploiting patches of different rewards. Pre-harvest information and a bimodal (rather than uniform) distribution of patch qualities appeared to improve foraging performance. Patch use in heterogeneous environments appears constrained by "missed opportunity" costs and cognitive processes. |
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| Item Description: | Vita. "Major Subject: Wildlife and Fisheries Sciences". |
| Physical Description: | xiii, 133 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references. |