Delayed induction of a filial predisposition in the chick after anaesthesia.
In domestic chicks, Gallus gallus domesticus, early filial preferences are formed as the result of at least two processes: learning by exposure to conspicuous objects (filial imprinting) and a developing predisposition to approach some stimuli rather than others. The predisposition may be measured in visually naive chicks, e.g. as a preference for a rotating stuffed jungle fowl hen rather than for a rotating red box. Non-specific experience, such as handling or being placed in a running wheel in darkness, for a short time, is sufficient to induce the predisposition. In Experiment 1, the existence of a sensitive period for the induction of the predisposition, between approximately 14 and 42 h after hatching, was confirmed. The putative effect of anaesthesia on the induction of the predisposition was investigated in Experiment 2. Soon after hatching dark-reared chicks received injections of the anaesthetic equithesin (0.12 ml, I.P.), or saline, or they did not receive injections (controls). The chicks were subsequently placed in running wheels for a total of 2 h at either 24 h or 48 h after hatching. The following day the chicks' preferences were tested. In the 24 h-chicks, the saline and control groups showed a significant mean preference for the stuffed fowl, whilst the equithesin group did not. In contrast, in the 48 h-groups of chicks, only the equithesin group showed a significant mean preference for the stuffed fowl. These results suggest that the anaesthetic equithesin affects a developing filial predisposition in the domestic chick, and does so by delaying the onset of a sensitive period for the induction of the predisposition.
Bolhuis
J J
JJ
University of Cambridge, Department of Zoology, Madingley, UK. jjb19@cus.cam.ac.uk
Horn
G
G
D000758:Anesthesia; D019162:Anesthetics, Combined; D000818:Animals; D000831:Animals, Newborn; D002645:Chickens / Q000502:physiology*; D002697:Chloral Hydrate; D003624:Darkness; D007173:Imprinting, Psychological / Q000187:drug effects*; D008278:Magnesium Sulfate; D009043:Motor Activity; D010424:Pentobarbital
D019162:Anesthetics, Combined; C034864:chloropent; D002697:Chloral Hydrate; D008278:Magnesium Sulfate; D010424:Pentobarbital