In a variable environment, the ability to track food resources that vary in time and space may increase the foraging efficiency of individuals. Tracking can be accomplished by repeatedly visiting patches, but this sampling will be economical only if its benefits outweigh its costs. I examined the effects of patch characteristics and social factors on sampling using simulation models and both large- and small-scale field experiments on eastern chipmunks ( Tamias striatus). In the first experiment, chipmunks discovered large renewing patches within a few days, sampled them frequently enough to detect most renewals, and then decreased their sampling effort after renewal ceased, showing that they can track patches over both long and short time scales. Sampling rate was higher for animals that lived near the patch, for animals that were more aggressive while in the patch, and when the number of other animals that sampled was high, but was unaffected by the quantity and frequency of renewal. I developed a model, which predicts that the optimal sampling frequency should increase with the frequency and duration of renewal and with the rate of gain in the patch, and decrease with the duration of each sampling trip. An extension of this model predicts that conspecifics will affect even non-group foragers, by competing for food and providing social information. A second field experiment showed that chipmunks decreased their sampling in response to higher competition. Although chipmunks used social information to discover a patch, there was no indication that social information caused a decrease in sampling. In conclusion, sampling to keep track of varying patches is an important component of the foraging behaviour of chipmunks. Optimal sampling behaviour is affected by patch characteristics and sampling rate will depend on (i) the ease with which animals can estimate these characteristics, (ii) the level of competition, which can alter the patch valu
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.84256 |
| Date | January 2003 |
| Creators | Hall, Carolyn L. |
| Contributors | Kramer, Donald L. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Biology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 002085354, proquestno: AAINQ98269, Theses scanned by UMI/ProQuest. |
Page generated in 0.0018 seconds