Abstract
Electrolytic lesions in the ventral hypothalamus of 28 adult male white‐crowned sparrows interrupted photoperiodically induced hyperphagia and fat deposition. Lesions in posterior regions of the infundibular nuclear complex or median eminence (22 birds) eliminated both the fattening response and testicular recrudescence. Lesions restricted to the anterior division of the median eminence or the tractus hypophyseus (6 birds) eliminated the fattening response only.