Meeting Abstract
Zonotrichia leucophrys oriantha (MWCS) are unique in that their nestlings have a 25% higher metabolic rate than other open-nesting passerines. Nestlings do not develop endothermy until 3-4 days after hatching and are not fully homeothermic until the time they fledge. Thus, MWCS parents must provide for their own metabolic needs and the nestlings’ elevated metabolic and thermoregulatory needs in the variable temperatures and harsh conditions of a high-elevation environment. Ultimately, MWCS parents must balance their time between feeding and nest thermoregulation in order for the nest to fledge. I hypothesized that this tradeoff in parental nest attendance behavior varies on colder versus warmer days: feeding rates are reduced and/or delayed on cold mornings and on hot afternoons. These patterns accommodate for incubation during early hours and shading from intense sun during afternoon hours. This was tested by monitoring MWCS nests with data loggers that recorded ambient temperature every two minutes and a nest camera that revealed the frequency of different behaviors. Analysis showed a significant but extremely weak negative correlation between the frequency of feeding and temperature (R2 = 0.063831, p = 0.0042) and between the proportion of time parents were absent from the nest and temperature (R2 = 0.047224, p = 0.0141). ANOVAs of both temperature with feeding frequency and temperature with parental absence over 3.5 hour intervals revealed that cold mornings have higher feeding frequency but a lower proportion of parental absence than warm mornings. In cold afternoons, there is a higher feeding frequency but an equivalent proportion of parental absence as warm afternoons. However, only the difference in morning feeding frequency is significant (p = 0.03). This pilot study shows promise in revealing interesting trends should the sample size be expanded across multiple field seasons.
