PARENT SESSION
Poster Session 28: Avian Ecology
Thursday, August 11, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Latitudinal differences in avian reproductive ecology and behavior: a comparative framework.

Robinson, Tara^*,1, Robinson, W. Douglas¹, ¹ Oregon State University, Corvallis, OR

ABSTRACT- Latitudinal differences in life histories have intrigued ecologists for decades. Avian clutch sizes, for example, increase consistently from equatorial to temperate regions, yet underlying mechanisms and associated patterns in life history variation remain poorly understood. In large part, a paucity of knowledge from tropical locations limits our abilities to test predictions from theory. Since 2003, we have monitored bird nests in lowland forests of Panama and Michigan from phylogenetically paired taxa. We used video cameras to quantify nest attendance and identify nest predators. Other traits we measured include: nest fate and exposure days, egg measures (clutch size, mass, sizes), nestling growth, incubation and nestling periods, activity patterns of parent birds, and response to human approach to the nest. The last trait provides an index to parental response to a standardized threat and helps inform us of differences in how parents may value their offspring relative to their own safety. To date we have more than 900 nests in Panama and 750 in Michigan. Temperate taxa have larger clutch sizes, smaller eggs, faster nestling growth, shorter incubation periods, and respond more aggressively to intrusions at nests. Tropical birds are usually shier at the nest, but have similar nestling periods and similar feeding rates to temperate congeners. Although many of the differences in reproductive ecology fit predictions of life history theory, several traits do not vary across latitudes suggesting a stronger influence of evolutionary history than environmental variation on life histories of these birds.

Key words: life history