WILD THING

Shrikes in the City

Biologists study the ‘butcher bird’ in hopes of reversing its decline.

by Paula Levihn-Coon

In Old Settler’s Park in Round Rock, loggerhead shrikes make their homes in small trees next to asphalt streets and busy playing fields.

“There’s tons of human activity, packed parking lots, lots of people on the weekend, yet the shrikes choose to put their nests in these trees,” says Tania Homayoun, a Texas Parks and Wildlife Department biologist studying the birds.

Striking black, white and gray loggerhead shrikes sport hooked beaks and black eye-masks. They live exclusively in North America, from Mexico to Canada. Northern populations migrate, but southern populations, like those in Texas, are year-round residents.

Loggerhead shrikes experienced a 74 percent population decline from 1970 to 2014. The U.S. Fish and Wildlife Service has designated them a “migratory nongame bird of management concern.” Scientists fear that, if nothing is done to help, more than half of the population that existed in 2016 will disappear by 2040. Habitat loss, pesticide use and urban sprawl are likely reasons for their decline.

Insect-eating songbirds with raptor habits, loggerhead shrikes (Lanius ludovicianus) are nicknamed “butcher birds” for their macabre eating habits. (Lanius means “butcher” in Latin.) The butchers paralyze prey such as lizards and mice with a bite to the head, then shake them to break their necks. Sometimes they impale their prey on sharp thorns and barbed wire, returning later to devour the skewered animals.

Homayoun, TPWD biologist Craig Hensley and scientists from the Oaks and Prairies Joint Venture are studying the loggerhead shrikes in Old Settler’s Park. Their goal is to collect data to help determine the source of the birds’ decline and ways that urban land management can reverse the trend. The five-year study began in 2020.

Using binoculars, biologists and volunteers locate nests and learn when the mother starts incubating eggs, when the babies hatch, when the nestlings fledge and the location of impaled prey.

When eggs hatch and babies fledge, “we make sure to have eyes on the nest,” Homayoun said. By knowing the incubation time (15-17 days) and the nesting period (16-20 days), the bird-watchers know when to act. When they spot a mother leaving her nest just after a hatch, they hustle to make a video of the nestlings with a cellphone attached to a telescoping pole, documenting the nest materials and number of babies hatched.

When nestlings fledge, Homayoun and Hensley band them under a federal permit. They lure a juvenile shrike into a wire trap with live bait — either large crickets or a mouse. The location and colors of the bands they attach uniquely identify the bird, enabling the biologists to document its territory and lifespan. Then they measure the bird, photograph it and release it.

By monitoring individual birds, the scientists have been able to document bird deaths, which might lead to recommendations to prevent the deaths. A volunteer witnessed a Cooper’s hawk taking a baby shrike out of its nest. Another volunteer found a banded male shrike dead in a tree.

The next time you venture to Old Settler’s Park, look for loggerhead shrikes or their unfortunate victims. You might even spot the biologists studying the shrikes.