LE3 .A278 2005

2005

Shutler, Dave

Acadia University

Master of Science

Masters

Biology

Biology

Parental effort can be strongly tied to energetic demands of a brood. In this two-year study, I experimentally manipulated brood size and flea (' Ceratophyllus idius') load in tree swallow ('Tachycineta bicolor ') nests to determine the influence of these variables on parental effort, nestling begging vocalizations, and nestling condition. Parental effort (feeding and defence) and begging vocalizations (length, rate, and amplitude) were measured when nestlings were 8, 10, and 12 days old, and nestling condition (mass and structural size) was measured when nestlings were 12 days old. Parental feeding rates increased with brood size, but per capita feeding rates decreased with brood size. Also, brood begging rates increased, while average nestling mass decreased, with brood size. These results may indicate that, because parents did not compensate for increases in brood size, nestlings in enlarged broods were of poorer condition and therefore begged for more food. However, parents did not appear to base feeding rates on variation in begging calls, so further investigations of this signalling system in experimentally manipulated broods may be warranted. Although no variables were significantly related to flea load, flea manipulations did not result in higher flea loads than in control nests. Therefore, before further studies of this host-parasite system are undertaken, the population dynamics of 'C. idius' in nest boxes should be resolved.

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https://scholar.acadiau.ca/islandora/object/theses:3085