Neurally active stress peptide inhibits territorial defense in wild birds

It is unclear whether the behavioral effects of peptides in laboratory stud ies always reflect natural conditions. Here we test whether we can detect m easurable behavioral changes after rapidly injecting peptides into the brai ns of wild birds. We used a modified stereotaxic-like technique to inject c orticotrophin-releasing factor (CRF) and arginine vasotocin (AVT, the nonma mmalian form of arginine vasopressin), two hormones important in the stress response, into the brains of wild, freely behaving, male white-crowned spa rrows (Zonotrichia leucophrys). We then monitored subsequent territorial be havior to determine whether CRF or AVT altered this behavior. Surprisingly, the potent stressors of capture and surgery did not eliminate territorial behavior, with many birds resuming territorial defense within 60-90 min aft er surgery. Centrally acting CRF, however, significantly reduced territoria l defense whereas centrally acting AVT had no effect. These results indicat e that the behavioral affects of peptides can be studied under natural cond itions. (C) 1998 Academic Press.