Abstract

Photosensitive redheaded buntings were kept at short daylength (SD, 8L/16D) for 7 days. These birds were then exposed to long daylength (LD, 13L/11D) to induce migratory restlessness i.e. zugunruhe. The experiment was continued till termination of zugunruhe in each bird. The actogram shows that birds held at short days show activity only during light period (pre-migratory stage). Upon exposure to long days birds start showing nighttime activity (zugunruhe). Nighttime activity indicates that birds have attained migratory stage in simulated photoperiodic conditions. Birds stop their nighttime activity after showing zugunruhe for many days. The total activity count is highest during migratory stage of buntings. We can say that with increase in day length the buntings show night time restlessness i.e. zugunruhe and this is the mark of onset of migration. Because of their night time activity, the total activity count is high during migration. Buntings store highest amount of body fat in sub-cutaneous adipose tissue during migratory period. This adipose-stored fat helps the bird to fuel their migratory flight. Increase in bodily fuel stores prior to long-distance flights is an important metabolic feature of migratory birds.

Description