By Sarah Díaz for The Island Eye News
Fall migration is well on its way at the Sullivan’s Island Bird Banding Station! I have banded two species of vireo so far this season—White-eyed Vireo and Red-eyed Vireo. Both species are utilizing the Protected Land as a stopover location during their long distance journeys to the Tropics. I am encountering mostly younger birds that hatched earlier this year. Young Red-eyed Vireos actually have brown eyes that will eventually turn red. Similarly, the young Whiteeyed Vireos I band have gray eyes that will gradually turn white. The bird pictured is a White-eyed Vireo. Males and females of this species have identical plumage, so the sex of this bird is unknown. The age of this bird was determined by several factors, including its wing coverts, degree of skull ossification and eye color.
The skull can be quickly and safely examined by spraying a small amount of water on the head and parting the feathers to see through a small window of skin. Observing the degree of skull ossification is a very helpful method experienced banders use to age songbirds during the Summer and early Fall.
Songbirds’ skulls fully ossify by November at the latest, so other ageing methods are utilized later in the Fall season.
If you would like to visit the Sullivan’s Island Bird Banding Station, you can contact Sarah Díaz at email@example.com.