LE3 .A278 2018

2018

Shutler, Dave

Acadia University

Bachelor of Science

Honours

Biology

Biology

Avian nest defense is a particularly sensitive form of parental investment. Flushing distance (the distance at which a bird flies from a nest when a predator approaches) during incubation is one measure of nest defense; parents that stay too long risk being eaten, whereas those that flush too early risk slowing development of their eggs. The general prediction is that incubating birds will remain on a nest that is being approached by a predator until risks of staying reach a threshold that outweigh costs of fleeing. This threshold is assumed to vary depending on the value and habitat characteristics of a nest. I evaluated flushing distance in tree swallows (Tachycineta bicolor) relative to clutch size, initiation date, stage in development, environmental temperature, time of day, day of the year, visit number, and overhead and lateral vegetation density. I obtained 185 flushing distances from 34 different nests in Port Williams, Nova Scotia, Canada. For non-parametric correlations, flushing distance increased with clutch size, and decreased with overhead vegetation density and air temperature; remaining associations were not significant. Sample sizes prevented me from considering interactions among variables. For the univariate parametric linear regressions only overhead vegetation density was significantly associated with flushing distance. Finally, my review of the literature found limited support for most of the associations I tested, suggesting that further insights are needed into this aspect of parental investment.

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https://scholar.acadiau.ca/islandora/object/theses:2617