Meeting Abstract

50.6  Monday, Jan. 5  Physiological and behavioral responses of molting house sparrows to protein stress BURNS, Darren J*; BAUCHINGER, Ulf; MUKHERJEE, Shomen; PINSHOW, Berry; Ben-Gurion University of the Negev; Ben-Gurion University of the Negev; Ben-Gurion University of the Negev darrenjo@bgu.ac.il

Birds use both physiological and behavioral mechanisms to gain and conserve protein when they molt. Therefore, we hypothesized that molting birds will forage for longer and enter deeper nighttime hypothermia, than birds not undergoing molt. We divided 18 house sparrows (Passer domesticus) into three equal groups: unmanipulated controls; a group from which we plucked 5 retrices and 5 flight feathers from each wing; and a sham-plucked group with the same feathers cut off above the calamus (to control for the energy expenditure of molt). Each bird had a thermosensitive transmitter implanted in its peritoneal cavity. The birds were fed 50% of their average daily food requirement for 2 days, to induce nighttime hypothermia. By day, we measured their foraging rates. Contrary to our predictions, we found that plucked birds had significantly lower foraging rates (p=0.008) than the unmanipulated control group (1.94±0.29 vs. 2.24±0.29; SE=0.96,). There were no significant differences in foraging rate between the plucked birds and the sham controls. However, a P value of 0.07 for the difference between the sham-plucked and unmanipulated control groups (sham-plucked 2.16±0.22 vs. control 2.24±0.22; SE=0.96) hints that flight was the major energy cost and the addition of the extra energy needed for molt contributed to making the difference significant between the plucked and control birds. Although resting, food-limited birds lowered their body temperatures more than those fed ad libitum, there was no significant difference among the groups. We concluded that it of greater benefit for molting birds to reduce activity to conserve protein, than to forage more in order to take in extra protein.