Sunning behavior in Black Kite (Milvus migrans): an opportunistic observation from South India

Sunning is a widespread avian behavior with significant physiological and ecological implications, including thermoregulation, feather maintenance, and ectoparasite control. In Black Kites (Milvus migrans), sunning involves adopting a distinctive posture to maximize exposure to solar radiation. However, the functional significance of this behavior remains insufficiently understood. This study presents an opportunistic field observation conducted during a Raptor Monitoring Program at Kollam Beach, Kerala, on 17 November 2024. A single Milvus migrans was observed sunning at 11:30 AM, lying horizontally on beach sand with its wings and tail fully outstretched and head slightly elevated, directly facing the sun. Ambient air temperature was recorded at 33°C, while sand surface temperature reached 51°C. The posture and environmental conditions suggest antiparasitic advantages, with intense solar and substrate heat potentially aiding in ectoparasite control by exposing feather lice to lethal temperatures. Although anecdotal, the study contributes to our understanding of the adaptive value of heliothermic behavior and highlights the importance of natural history observations in avian behavioral ecology. Further research is recommended to quantify the effects of sunning on parasite loads and to examine its ecological function across varied habitats.