Smithsonian researchers hatch ‘butcher birds’

A recently hatched loggerhead shrike sits perched on a branch at the Smithsonian Conservation Biology Institute in Front Royal. Courtesy photo

The loggerhead shrike is in decline and researchers at the Smithsonian Conservation Biology Institute in Front Royal are part of an ongoing effort to figure out why.

In early May, the institute saw 10 loggerhead shrikes hatch from three different pairs of shrike.

Warren Lynch, head of the institute’s bird programs, noted that the institute is expecting to transport the birds to the Toronto Zoo for a reintroduction program within a couple of weeks.

The Loggerhead shrike is commonly called “the butcher bird” because it impales its prey — which largely consists of bugs and small snakes — on sharp objects such as thorns or barbed wire.

Once an abundant species in Canada, Virginia, much of New England and parts of thge southern United States, the “butcher bird” has been in a sharp population decline over the last several decades.

Lynch said peer review literature has reported an overall decline in the shrike population of “about 70 percent over [the] past 50-60 years.”

Lynch said they are not sure why the loggerhead shrike is disappearing at such rates.

“Habitat is always a big front-runner with most species that are declining,” Lynch said. “That’s kind of where we want to focus first, before expanding to other areas.”

Lynch added that they believe that it could most likely be a combination of different factors that have lead this decline.

At the moment, researchers at the institute in Front Royal are monitoring the recently hatched birds until they are transported to Canada.

“Generally, we like to keep them with their parents for at least three weeks … when they first come out of the nest,” Lynch said, adding, “Because of the way they feed … there is some learning that goes on.”

To aid this development, Lynch said they provide the young shrike with live prey so that the birds can get used to that kind of hunting while in captivity.

On top of ensuring that the shrikes are mature, Lynch said the birds must be screened for their health, parasites and any diseases they might be carrying.

With the rise of avian flu in the Midwest, Lynch said, “That could restrict any transport from areas where avian influenza has been documented.

“Luckily, it is not a problem in Virginia yet, although it could be in the near future. We’re hoping to pull this off before there’s any concern with that.”

The bird flu is impacting the country’s poultry industry and Lynch said they are keeping an eye on it.

“It depends on what Canada requires for us to bring those birds across the border,” Lynch said.

“Any birds that are reintroduced … are going to be banded, so we would get information from any band returns or sightings for those birds,” Lynch said.

The banding will provide researchers with critical information on the birds’ location preference, migratory patterns, breeding grounds and mortality in different habitat types.

“Once we get [the program] up and going … we do hope to do releases here in Virginia,” Lynch said.

The Front Royal institute is working with officials in the Virginia Department of Game and Inland Fisheries as well as the West Virginia Department of Natural Resources to research the shrike’s biology.

“We’ve been going out and doing field surveys with them, collecting feather samples from the birds, banding birds,” he said.

Lynch said any reintroduction program for Virginia would be complicated, since researchers are unclear as to which subspecies of shrike live in the state.

“Virginia, historically and probably still, has migratory as well as resident birds,” Lynch said. “The question, ‘Which birds are actually breeding here?”

Lynch said captive releases of loggerhead shrikes in Virginia are several years down the road, and depend on when researchers can answer that question.

Moving forward, Lynch said the institute has some birds that are “sitting on a second clutch” with 11 total eggs that could hatch within the next week.

“Out of that, I’m hoping that we’ll get half of those to hatch,” Lynch added, noting the his estimates are due to the fact that the eggs are coming from an older female shrike.

“We might end up retaining some of these birds for future breeding pairs,” Lynch said. “Some of these birds might be retained in captivity up in Canada.”

Contact staff writer Kevin Green at 540-465-5137 ext. 155, or kgreen@nvdaily.com