Conquering the night: understanding nocturnal migration in birds

Abstract

Migration is a biologically distinct and unique phenomenon that enables the birds to migrate twice-a-year between the breeding and wintering grounds. These movements are known as spring and autumn migration, respectively. Depending on their inherent programming, the migratory birds may fly during day or night or both. Different environmental factors such as, temperature, food, predator pressure and physiological demands of energy storage and expenditure, contribute to the pattern of migrations, day or nighttime. Since, most of them are nighttime migrants they have to make dramatic changes in their physiology and behavior to transform them from being diurnal to predominantly nocturnal. These changes result in different life history stages (LHSs) such as migration, reproduction and molt, in their annual cycle, which are regulated by endogenous circadian and circannual clocks. As a result, the birds start preparing well in advance for the approaching LHS. The present review focuses on behavioral strategies of a nocturnal migrant and understanding of the possible physiological responses to ensure successful migration.

Keywords:

• Birds
• fattening
• food intake
• nocturnality
• spring migration
• stopover
• Zugunruhe

Acknowledgments

Financial supports from the Department of Biotechnology, New Delhi is gratefully acknowledged. Ruchi Komal is a recipient of UGC BSR Research Fellowship. Khushboo, Anshu Dwivedi and Vaibhav Vaish are recipients of DBT Junior Research Fellowship.