Of all the fascinating and inspiring facts about birds that I’ve learned during my tenure as editor of Birder’s World magazine, the most amazing is that so much remains to be learned — and that what we don’t know yet may well hold the key to ensuring that the birds you and I enjoy today are healthy and abundant tomorrow.
The list of unanswered questions about migratory birds is especially long, and understanding how and when they use urban natural areas is at the top of the list.
As I’m sure you know, this is a major focus of the work of Julie Craves, who in addition to being a contributing editor and the author of the popular regular column Since You Asked, serves as the supervisor of avian research at the Rouge River Bird Observatory.
In fact, Julie just published the results of that research in the Wilson Journal of Ornithology, the respected quarterly journal of the Wilson Ornithological Society. Here's the title of her paper and the abstract:
A Fifteen-Year Study of Fall Stopover Patterns of Catharus Thrushes at an Inland, Urban Site
By Julie A. Craves
The Wilson Journal of Ornithology 121(1):112–118, 2009
ABSTRACT. Little is known about how landbirds use urban habitats as migratory stopovers despite increasing urbanization in North America and the importance of the migratory period to annual survival of birds. I examined 15 years of autumn stopover data for three species of migratory Catharus thrushes from an urban natural area in metropolitan Detroit, Michigan, USA. The majority of birds were in good condition on first capture with 59% having more than a just a trace of fat, a higher proportion than reported for passerines at other fall stopover sites. Condition was similar among species, and there was little difference in fat class or mass between age groups. A linear regression of the condition of each bird at first capture and time of capture indicated positive diurnal mass gains in two species and mass loss in the third. Fourteen percent of thrushes banded were recaptured. Lean birds were not more likely to be recaptured than fatter birds and, among recaptured birds, there was no difference in stopover period or mass or fat increases between young and adults. Seventy-nine percent of recaptured birds gained mass, and mass and fat class increases were significant for all species. These results are discussed in view of the high prevalence of non-native fruit resources and rates of human disturbance at the study site. Received 5 April 2008. Accepted 14 August 2008.
Just how important is Julie's work? Despite the ever-increasing loss of crucial habitat to urbanization, hers is the first published long-term study of stopover ecology of migrant birds in an urban natural area. The first.
We couldn't be prouder of Julie's work or more pleased that she's a member of the Birder's World team. Please join me in congratulating her on her accomplishment. --C.H.