LE3 .A278 2004

2004

Taylor, Phil

Acadia University

Master of Science

Masters

Biology

Biology

Our understanding of broad-scale landbird migratory patterns is extensive; however, knowledge of small-scale species- and population-specific migratory patterns is generally limited. Migrant landbirds in eastern North America are faced with increased survival risks that are associated with migrating along and stopping over in coastal regions, but there is little understanding of the impact these migratory risks could have on avian populations. Therefore, an understanding of small-scale and population-specific migratory patterns and the mechanisms influencing these patterns will enhance our ability to assess the impact of migrating along coastal regions. To better understand migratory patterns in this geographic region, and the factors influencing them I assessed sources of variation in orientation behaviour of Yellow-rumped Warblers ('Dendroica coronata'). The orientation behaviour of Yellow-rumped Warblers was studied using a new video-based orientation cage that permitted temporal analysis of orientation behaviour during user defined time intervals, an advancement over previous methodologies that relied upon cumulative data. I used two experimental treatments to test for the effect of view of the horizon on orientation behaviour. Then using circular regression models, I examined the effect of a variety of variables and the experimental treatments on orientation. The model that showed the best fit to the data indicated that experimental treatment, fuel reserve, breeding origin, and wind conditions influenced orientation. Individuals chose more seasonally appropriate directions and their directions were more concentrated, especially after sunset, under exposed experimental treatment. The influence of an individual's breeding origin on orientation indicates that population-specific migratory preferences likely contribute to observed regional migratory patterns.

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