MOORE, Ignacio T.; BELDEN, Lisa K.; PERFITO, Nicole; LERNER, Darren; WADA, Haruka; WINGFIELD, John C.: Seasonality in an equatorial population of rufous-collared sparrows

Most northern latitude bird species display seasonal reproduction, territoriality and molt. Typically, males aggressively guard territories and mate during the spring and early summer and subsequently go through prebasic molt (replacement of all feathers) after the breeding season when the gonads are regressed. This seasonality is largely driven by seasonal environmental cues such as photoperiod. We are investigating the seasonality and endocrine control of reproduction, territoriality and molt in an equatorial population of the rufous-collared sparrows, Zonotrichia capensis. We have color banded approximately 250 individuals in the Papallacta River valley at 00 latitude and 3300 meters altitude in Ecuador. The environment is relatively constant year-round with no seasonal change in photoperiod. We have monitored this population during four periods of the year: February, May, July, and August-September. During February all individuals were molting, non-territorial, had regressed gonads and basal sex steroid levels. During May individuals were at all stages of reproduction but not molt. During July, individuals were paired up but had regressed gonads and were not molting. Individuals were at all stages of reproduction during August-September and were actively guarding territories but not molting. Thus, molt appears to be seasonally organized while reproduction may occur during an extended, less well defined period. In addition, there could be yearly variation, with plasticity in seasonal patterns dependent on local conditions. Future studies will continue to monitor the population and attempt to determine which cues are used to synchronize the population.