Meeting Abstract

P3.12  Friday, Jan. 6  Effects of various photoperiod treatments on the molt schedule of house finches. DE CASTRO, DM*; ZYLBERBERG, M; BRAZEAL, KR; HAHN, TP; University of California Davis

Avian life history events are highly seasonal and dependent on their environment. Deviations in the environment can interfere with the timing of these events. For example, climactically mild years and increases in food availability may prolong breeding activity and delay the onset of molt in temperate zone songbirds. Given that molt schedule (the timing and rate of feather replacement) is dependent on photoperiod, a delay in the start of molt may affect the rate of feather re-growth. This in turn could affect trade-offs between molt and other biological functions and reduce individual feather quality. In this study, three groups of house finches (Carpadocus mexicanus) were exposed to photoperiods that rapidly increased from 15L to 18L (long day), followed a natural photoperiod (natural day), or rapidly decreased from 15L to 12L (short day). The short day group molted at a faster rate and greater intensity than the natural day group whereas the opposite was true for the long day group. As these results demonstrate, the rate of molt can be changed depending on time molt commences during the year. House Finches molting later molt faster due to decreasing day length and vice versa. Further research will investigate the influence of molt rate on factors of individual quality such as feather quality and immunocompetence.