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Vol. 2 | No. 2 | June 2009   

 

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Avian Abattoir

By Jim Cox, Biologist, Vertebrate Ecology

The butcher bird of the Red Hills is finally getting some attention. This mockingbird-sized songbird goes by the professional name of Loggerhead Shrike, but locals often call it the butcher bird because of the bird’s curious habitat of hanging prey on barbed wire fences and broken off limbs. The sight of grasshoppers, lizards, and even small birds seen dangling from a wire fence are sure indications of shrike activity.

Over the past 30 years, the butcher bird has shown a steady decline of >3% per year throughout most of its range in North America. The declines are troubling, and shrike are now listed as a species of special management concern by many state wildlife agencies. Reasons for the declines are not well known, but potential factors include habitat loss, pesticide usage, and changing agricultural practices on private lands, and fire frequency and timber management on public lands.

Jonathan Gray, a graduate student at the University of Georgia, has netted nearly a dozen shrikes on Tall Timbers and Arcadia Plantation this summer and attached small radio transmitters. With help from Tall Timbers Research Station intern Hutch Collins, movements of the tagged shrikes are being monitored daily this summer, and the data collected for our Red Hills bird will be compared to data collected on shrikes found elsewhere in Georgia that live in areas dominated by agricultural land-uses.

Tagged Loggerhead Shrike

The study has produced some tantalizing early information. The nest productivity in the Red Hills appears to be double that recorded at other sites. Three nests in our region have each fledged 4 juveniles, while nest productivity at other locations has consistently been <3 fledglings. Grasshoppers, beetles and other large insects are the main summer staple of shrikes, and our frequently burned pinelands may provide a better diversity of food during the nesting season. The study is also providing information on shrike use of recently burned areas and fields, but data currently are too limited to summarize. 

Intern Hutch Colllings with shrike

With a little luck on the transmiiter front, we may be able to follow our Red Hills shrikes into the fall and winter when our region sees a big influx of migratory shrikes. These birds move south to escape a harsher winter environment and mix it up with the local birds. The winter diet typically includes more mice and small birds, and Jonathan is contemplating netting more birds at that time to help ascertain differences in the winter diet of resident versus migratory birds. Transmitters cost $200 each, so donations for this expanded shrike work will be much appreciated.

Lingering Effects of Tropical Storm Fay

The Red Hills Red-cockaded Woodpecker population seems to be experiencing some lingering effects of Tropical Storm Fay. The storm brought three days of torrential rain and increased juvenile woodpecker mortality in 2008. This breeding season, we’ve found low numbers in some territories that traditionally are very strong as well as a larger number of territories that contain single males. The overall productivity is lower this year, too, with an average of 1.9 nestlings per nest versus the long-term average of 2.1 nestlings. Here’s to hoping for a hurricane-free summer so our birds can start to recover.
The mission of Tall Timbers Research Station & Land Conservancy is to foster exemplary land stewardship through research, conservation and education.