BEHAVIORAL THERMOREGULATION IN CHICKS - THE BEST NEST

The ability of prehomeothermic chicks to thermoregulate behaviorally w as studied in chicks with continuous access to heated nests, running w heels, and separate sources of high and low protein. In Experiment 1, cold-reared groups with heated or unheated transparent nests ate the s ame amount and selected the same dietary fractions, but chicks with he ated nests ran less and grew faster. Despite this, groups maintained n ormal body temperatures. In Experiment 2, chicks were cold-or warm-rea red with heated or unheated painted nests, or no nests. Cold-reared ch icks with heated nests spent most of their-time in them. They selected diets containing a higher protein carbohydrate ratio than cold-reared chicks with unheated nests but ate less, thereby consuming less absol ute protein and growing more slowly. Despite differences in growth, in take, and dietary choice, all chicks maintained normal body temperatur es. These data reveal that behavioral thermoregulation has a privilege d status for chicks over the first 3 weeks of life. Prehomeothermic ch icks exercise complex and effective solutions to energetic challenges when offered behavioral options that simulate those available in natur e. (C) 1997 John Wiley & Sons, Inc.