Meeting Abstract
Reliable environmental cues, such as photoperiod, allow birds to time their reproduction to match peak food abundance for their offspring. It is possible, however, that more variable local cues, like temperature, can provide more temporally precise information about the timing of these food events. Resident birds especially should be sensitive to temperature cues and use them to modulate their reproductive timing on a fine scale. We conducted two experiments to examine the effect of temperature on reproductive condition in a resident songbird, the black-capped chickadee, Poecile atricapillus. In the first experiment, we exposed birds to three over-winter temperature treatments under semi-natural conditions and assessed gonadal development in the spring. In the second experiment, we used a 2×2 factorial design to assess changes in gonadal development and circulating testosterone levels of birds experiencing different temperatures under photostimulatory and non-photostimulatory photoperiodic conditions. Temperature had no independent effect on gonadal development or testosterone levels, but when photostimulated, birds exposed to warmer conditions became reproductively ready earlier than birds experiencing cooler conditions. We conclude that temperature acts as a supplementary cue that aids birds in the timing of reproduction.
