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Little Ricky became the sixth fledgling osprey in the Cape Region to be tagged and fitted with a transmitter by Richard “Rob” Bierregaard, who has been studying the population and migration patterns of osprey since 1969.
Little Ricky was tagged in Lewes at the nest at the Pilottown Road campus of the University of Delaware College of Marine and Earth Sciences, where faculty members had nicknamed the adults in the nest Lucy and Ricky.
Fish eaters, ospreys are one of the largest birds of prey in North America. Some reach 24 inches in length with a 6-foot wingspan. Ospreys were threatened with extinction until after the Environmental Protection Agency banned the pesticide DDT in 1972. “It’s gotten to the point now where no one’s counting ospreys anymore,” Bierregaard said, eliciting applause from his audience during a University of Delaware Ocean Currents Lecture Series presentation July 28.
University representative Joe Scudlark said Bierregaard’s was one of the most popular Ocean Currents presentations, drawing more than 180 people. Bierregaard discussed the habitat, hunting and eating, mating, nesting, breeding and physical characteristics of ospreys. But his most fascinating tales were about discovering and recording their migration patterns.
Bierregaard said that by 2004 research had established generally uniform adult bird migratory patterns, often over water from North America into South America, based on the adults’ faithful annual returns to their nesting and wintering spots. Wanting to learn about the birds’ first flights, when they would be operating on instinct with no destination in mind, he began attaching transmitters weighing approximately one ounce to young ospreys that year.
The Friends of Cape Henlopen State Park and Delaware State Parks are high on Bierregaard’s list of eight collaborators who have supported his tagging and migration projects.
In 2006 he tagged three Cape birds. Erica and Lew died. Della’s signal was lost this spring, two months before she was expected to return to the area a year following her initial two-year migration. Bierregaard said some have a lingering hope Della may still be alive.
Two birds were tagged in 2007. Patience died north of Panama. Claws has survived and has settled down near a reservoir in Venezuela. He is expected to return during the spring of 2009.
“There is a very high risk of birds not returning,” said Bierregaard, adding that the juvenile mortality rate for osprey is close to 80 percent during the first year.
The migrations of more than 120 adult ospreys have been recorded and Bierregaard has tagged 21 fledglings. Bierregaard said he plans to track the juvenile birds one more year before publishing the results of his migratory studies.
The GPS transmitters now used cost approximately $4,000, and deliver amazing results. “The old transmitters were fine for recording general migration patterns, but with the GPS we can tell which tree the bird is in,” Bierregaard said. Monitoring costs range from $400 the first ear to $500 - $1,000 in following years.
More information, including migratory maps and regular updates on the travels of all of the young ospreys, is available online at www.bioweb.uncc.edu/bierregaard/ospreys.htm.
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