The Giant Otter (Pteronura brasiliensis) is an endangered otter of Amazonian lakes and rivers. It is the only otter of 13 extant species to breed cooperatively in family groups, with young of several years helping to raise younger siblings. I studied giant otters' behavior and ecology in 4 oxbow lakes (or "cochas") in the Manú Biosphere Reserve, Perú during 2003-2006. The objectives of this research were: (1) to investigate whether oxbow lakes return to random or predictable faunal communities after annual flooding; (2) to document seasonal and annual patterns in the diets of giant otters on two phytoplankton-dominated oxbow lakes; and (3) to document and characterize helping behavior in giant otters.
I initially classified the four study lakes into 2 lake types, phytoplankton-dominated lakes and macrophyte-dominated lakes. I obtained data on their faunal communities, limnology, and otter diet through four seasons of 2003, and during the dry-seasons of 2004-2006. I show that lakes' bird communities and caiman populations, and to a lesser degree fish communities, respond predictably by lake identity and type. Lake communities also responded to seasonal changes in 2003 data, but generalization to other years is complicated by the destructive flood in January of that year.
I studied giant otters’ diet using visual observations, and demonstrated seasonal and annual changes not previously reported for the species. Giant otters shift to more intensive use of small cichlid prey found in edge habitats when with young cubs in the dry season.
In studying the giant otters' behavior, I showed that hunting skills and helping activities generally increase with age. This observation is consistent with a pattern of "slow learning" suggested by the Skills Hypothesis of Heinsohn (1991). I observed considerable variation in dispersal age and helping contribution within families, particularly with respect to defensive behaviors against potential threats.
Finally, the elderly matriarch in one family switched from being a provider of large prey to a beggar from other family members in 2007, apparently from the effects of old age. During 8 days of observation, her offspring assisted her through sharing prey and other types of assistance.
|Commitee:||Burmeister, Sabrina S., Powell, Roger A., Whalen, Stephen C., White, Peter S.|
|School:||The University of North Carolina at Chapel Hill|
|School Location:||United States -- North Carolina|
|Source:||DAI-B 69/11, Dissertation Abstracts International|
|Subjects:||Ecology, Zoology, Limnology|
|Keywords:||Amazon, Cooperative breeding, Manu Biosphere Reserve, Otter, Oxbow lake, Peru, Pteronura brasiliensis, Shallow lake|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be