Meeting Abstract
Every year, thousands of birds make long and costly trips migrating. The successful navigation that supports migration in part relies on the use of a geomagnetic compass. Cluster N, a forebrain region thought to control the geomagnetic compass, is active at night when captive night-migrating birds are exhibiting nocturnal migratory restlessness (Zugunruhe). However, no comparisons of Cluster N activation within the same species of a night-migrant have been made between birds exhibiting Zugunruhe and those not exhibiting Zugunruhe at night. This led us to ask: Does Cluster N activity have a circadian cycle during migration season, regardless of migration behavior, or is it more facultatively regulated on a night-to-night basis? We housed 18 white-throated sparrows (Zonotrichia albicollis), a night migrant with frequent stop-over periods, in outdoor aviaries. Brains were collected during the day or at night. In the night, brains were collected from birds that were exhibiting Zugunruhe as well as those that were inactive, as observed with IR video cameras. Thus, we had birds in three different groups: day (n=5), night migratory active (n=7), and night migratory inactive (n=6). We used immunohistochemistry to quantify immediate-early gene expression (ZENK expression) in Cluster N. Based on preliminary analyses, birds in the night migratory active group had significantly greater numbers of ZENK activation in Cluster N than those in the day, and more importantly, night migratory inactive groups. This leads us to conclude Cluster N is behaviorally regulated on a night to night basis, and given its likely control by retinal stimulation, reflects “eyes open” during nights with migration.
