Meeting Abstract

P3.5  Saturday, Jan. 5  Seasonality of territorial aggression in equatorial rufous-collared sparrows Zonotrichia capensis CLASS, A.M.*; MOORE, I.T.; Virginia Tech; Virginia Tech classam@vt.edu

The majority of studies of avian behavior are aimed at species existing in distinctly seasonal, high-latitude environments. In these populations, territorial aggression is often associated with periods of reproduction. However the majority of bird species exist at tropical latitudes where seasonal environmental cues are less predictable. Despite inhabiting less seasonal environments, some tropical species exhibit fairly consistent annual reproductive cycles. We examined the seasonality of territorial aggression in a population of year-round resident, equatorial rufous-collared sparrows (Zonotrichia capensis) in cloud forest habitat of Ecuador (0�35-37’S, 77�53-54’W; elevation 2100-2250m).We did simulated territorial intrusions (STIs) on resident male Z. capensis using a decoy and song playback to test if territorial aggression is seasonal. We tested birds during pre-breeding, breeding, feeding fledglings, molting and non-breeding. STI�s were divided into three ten minute periods: 1) pre- intruder (decoy covered, song playback off), 2) intruder simulation (decoy uncovered, song playing back), 3) post-intruder (decoy covered, song playback off). The following aggressive behaviors were measured: time within 5 m of the intruder, closest approach to the intruder, number of songs, number of song-switches and number of flights. Using principle components analysis we then determined a single composite aggression score from the variables measured. We found significant differences in territorial aggression during different periods even with the relative population asynchrony. Despite the aseasonal environment of this tropical population of Z. capensis, we found that similar to high latitude species, males are most aggressive during breeding and least aggressive during molt.