Energy budgets, risk and foraging preferences in dark-eyed juncos Junco hyemalis
Behavioral Ecology and Sociobiology 8.3: 213-217
ISSN/ISBN: 0340-5443 DOI: 10.1007/bf00299833
Juncos' preferences for constant versus variable food rewards were tested in three series of aviary experiments. Deprivation and feeding rates were varied across the three treatments, but the mean of the variable reward equalled the constant reward in every experiment. When the birds gained energy faster than required to meet all 24-h costs, they preferred the constant reward. When the birds' energy intake was less than the minimally required rate, they preferred the variable reward. When energy intake just balanced average daily costs, the birds preferred the constant reward or were indifferent, and their response depended on the particular mean-variance combination presented.