Snooping on Red-Cockaded Woodpeckers
Revealing aspects of red-cockaded woodpecker ecology
- Wendee Holtcamp
- Apr 01, 2001
Biologist David Richardson didn't like climbing trees, but that was simply part of his job monitoring endangered red-cockaded woodpecker cavities. Tethered by a safety strap, he would climb 20 to 60 feet up a pine tree using a tall ladder, peer inside the tiny opening with a dental mirror and pen light, and count eggs or nestlings. One day in 1994, Richardson's safety belt unfastened and he took a 20-foot fall. Luckily, he sustained only minor injuries, but his fall initiated a new era in red-cockaded woodpecker management.
"I was extremely timid about climbing after that," says Richardson, who works at Mississippi's Noxubee National Wildlife Refuge. Richardson had seen a fiber-optic endoscope designed to look in cars for drugs, and thought to himself, "It would be great if we could come up with something like this to monitor nesting cavities."
Richardson tracked down inventor John Christensen of California-based Sandpiper Technologies, who had previously designed a camera for scientists studying owl nests. Working with Richardson, Christensen invented the Treetop Peeper, a miniature video camera mounted on a 50-foot telescoping pole that allows biologists to peer into woodpecker cavities. That was in 1996.
"Dave Richardson took his prototype to a conference and we started getting orders all over the place," Christensen says. Today, nearly every national wildlife refuge and national forest where the woodpeckers nest has at least one of the devices.
Red-cockaded woodpeckers are native to mature pine forests of the southeastern United States. They were listed under the original Endangered Species Act of 1973. Even with federal protection, however, their populations dropped through the 1970s and 1980s. The major reason for their decline was a quirky fact of their life history: The birds selectively prefer to raise their young in living pines more than 80 years old. But with extensive clear-cutting and shortened forestry rotations throughout much of the Southeast, few pines lasted 80 years and the woodpeckers had nowhere to go. Less than 5,000 acres of the original old-growth southern longleaf pine forest currently remains in the region. In contrast, nearly three million acres of younger, secondary-growth longleaf pine forest grows in the Southeast and Texas.
Red-cockaded woodpeckers "are the only bird in America that excavates a cavity in a living pine tree," says Ralph Costa, a U.S. Fish and Wildlife Service biologist who heads the species' recovery team. Only older pines develop red-heart disease, a fungus that softens the heartwood, making cavity excavation easier. To complicate matters, the woodpeckers live in territorial family groups, which require not one, but multiple old-growth pine trees for nesting and roosting cavities. Only in the 1990s, after biologists began using artificial cavities to supplement natural cavities, did populations stabilize and start to increase.
To get accurate population estimates, scientists have to locate active nests and monitor them during nesting season. That used to mean a lot of tree climbing, but Peepers enable biologists to check nearly triple the number of cavities in a given day.
Today, about 12,500 red-cockaded woodpeckers live in approximately 5,000 family groups, less than 3 percent of the birds' abundance when the first Europeans settled in America. Lack of suitable habitat, forest fragmentation and fire suppression continue to threaten the birds' recovery.
Before it can be removed from the Endangered Species List, the woodpecker must flourish with little, if any, human assistance, and that will require healthy old-growth pine forests. The 1985 Red-cockaded Woodpecker Recovery Plan allowed clear-cutting, but the newly revised draft 2000 plan recommends against clear-cutting of natural pine stands in all national forests, military installations and national wildlife refuges that provide habitat for the species, or that are potential recovery areas. "It is a bold move," Costa says. "Every acre of public land where the birds are will have some ancient trees." The revision advises using selective logging or leaving up to ten old-growth pine trees on each acre logged.
The plan makes recommendations to private landowners, including timber companies, but does not require them to follow the same forestry guidelines that are being proposed for public lands. However, says Costa, "There's no train wreck here, like [former Interior] Secretary Babbitt talked about with spotted owls. With private land we have a huge amount of cooperation." More than 100 landowners in five states are protecting 260 woodpecker groves by participating in the Safe Harbor Program, in which they voluntarily enhance woodpecker habitat but are not restricted from altering their land.
The revision to the species' recovery plan is based on years of research. "We have learned volumes and volumes about red-cockadeds," Costa says. "They are probably the most studied birds in North America." And Peepers have contributed a great deal to this knowledge base. Originally used solely to keep tabs on population numbers, Peepers have become valuable research tools that have revealed new aspects of red-cockaded woodpecker ecology.
One such discovery is the large number of species that depend on the woodpeckers' cavities. Eric Walters, a Florida State University graduate student, has looked in more than 6,000 cavities since June 1998. He has documented other species of woodpeckers, eastern bluebirds and several other species. So many species use the red-cockadeds' cavities that Costa thinks of them as the gopher tortoise burrows of the arboreal world. "That's why we call the species a keystone species," he explains. If the woodpeckers disappear, wildlife that depends on their cavities will suffer.
Another researcher, Clemson University graduate student Felicia Sanders, fixed permanent video cameras inside four red-cockaded woodpecker cavities to study nesting ecology in a South Carolina pine forest. "We've always known that they experience brood reduction, where the weakest nestling doesn't survive," Sanders says. But nobody knew how it happened. "Would the other nestlings attack it, or would it not get fed, get weak and die?"
Using time-lapse video surveillance, Sanders recorded nearly 5,000 hours of nesting behavior during 1998 and 1999. Watching the tapes, she learned that the weakest nestling died of starvation, probably because it wasn't begging as vigorously. This contrasts to other bird species, like masked booby nestlings, which actually engage in siblicide. Because red-cockaded woodpecker nests had never before been continuously monitored, Sanders also observed previously undocumented activities.
The ability of Peepers and similar video cameras to record animal behavior without human disturbance has potential to open a new chapter in wildlife research. Since their first use for woodpecker cavities, Christensen has modified Peepers to monitor a wide variety of animal homes that were traditionally difficult to study. "Treetop Peepers were first built for red-cockaded woodpeckers," says Christensen. "Now they're used for everything under the sun."
Texas journalist Wendee Holtcamp Peepered bird nests with scientists at the Noxubee National Wildlife Refuge while reporting this article. The red-cockaded woodpecker is one of 25 species highlighted in NWF's Keep the Wild Alive™ campaign. For more information, see www.nwf.org/keepthewildalive.