LE3 .A278 2014

2014

Shutler, Dave

Acadia University

Bachelor of Science

Honours

Biology

Biology

Predation accounts for greater than 60% of egg and nestling losses in many species of birds. Thus, crypsis (ability of an organism to avoid detection by other organisms) can be critical to egg, nestling, and parent survival. I studied behavioural crypsis, and in particular whether tree swallow parents use feeding “choreography” to avoid alerting predators of the location of occupied nests. Choreography was quantified as coordination of parental movement around nests, including both entry/exit angles and entry/exit timing. Twenty-two different tree swallow nests, located at four sites within the Annapolis Valley, were included in the study. During multiple 30-min observations at each nest, entry/exit angles and times of entries and exits were recorded. Feeding rate gradually increased during the first two weeks and slowly leveled off as offspring reached asymptotic size. Entry/exit angles deviated from a null expectation, but not in a manner which would suggest parents were attempting to deceive predators. Furthermore, there was no difference in vector preference between entries and exits. Feeding was more synchronous than expected by chance, with most feedings falling between 0 and 2 minutes of each other. Results support presence of choreography in behaviour, but not in the manner predicted. Further data and analyses may reveal other factors influencing choreography, and the value of choreography to fledging success.

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https://scholar.acadiau.ca/islandora/object/theses:1128