Date of Graduation

5-2012

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Biology (PhD)

Degree Level

Graduate

Department

Biological Sciences

Advisor

Kimberly G. Smith

Committee Member

Edward E. Gbur

Second Committee Member

Douglas A. James

Third Committee Member

Arthur V. Brown

Abstract

The Louisiana Waterthrush, Parkesia motacilla, is a migratory wood-warbler and breeding season resident of the eastern United States. Males defend breeding territories that extend linearly along clear, fast-flowing, gravel-bottomed, forest streams. Defense includes two song types, primary and extended song. As riverine specialists, birds rely upon aquatic invertebrates as prey and riparian habitat features for nesting. They use a unique foraging maneuver, leaf-pulling, that involves picking up or pulling a leaf from water, and turning it over to search for prey. Their relationship with riparian habitat introduces potential for Louisiana Waterthrushes to serve as indicators of stream health. The first objective was to determine if, during territorial defense, males exhibit the `dear-enemy' effect with neighbors, strangers, and neighbors at incorrect boundaries. The second was to determine physical properties of extended song with different levels of aggression to test Morton's (1977) motivational-structure rules of vocalizations. The third objective was to determine prey available in stream corridors as the result of leaf-pulling. The final objective was to determine how Louisiana Waterthrushes are affected by anthropogenic change in the watershed of the Buffalo National River and if functional relationships existed between territory size and common measures of riparian habitat quality. Territories were mapped and monitored on three watershed streams with legally protected and unprotected reaches. Birds were federally and color-banded and records of fidelity and nest-success were kept. Playback studies were run to test for neighbor-stranger and neighbor-neighbor discrimination and extended songs were analyzed alongside behavior. Territories were sampled for prey by simulating leaf-pulling. Bioassessment metrics were calculated. Males discriminated among neighbors, strangers, and neighbors at incorrect boundaries. Extended songs in more aggressive contexts had lower low-frequency components and longer suffixes of harsh, low-frequency components. Differences in prey were found among different areas in the stream corridor and different configurations of leaves. Aquatic invertebrate taxa differed with degrees of anthropogenic change. A functional relationship was found with lengths of territories and metrics indicative of riparian habitat quality and indicating that Louisiana Waterthrushes, as riverine specialists, could be useful bioindicators in the watershed of the Buffalo National River.

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