The ABCs of Lewis’s Woodpecker Conservation

For many decades we have suppressed the natural fire regimes of forests across the continent, primarily to retain the economic value of America’s timber and to prevent the loss of homes and humans living in the forest. This is especially evident in the West, where timber values soared through the last half of the 20th century. Prior to our settlement of the region, ponderosa pine forests generally experienced ground-clearing understory fires at three- to thirty-year intervals, creating enough snags (standing dead or partly-dead trees) to support healthy woodpecker populations.

Fire suppression facilitates the development of a dense forest understory, which serves as “ladder fuel” for a ground fire, sending the flames to the crowns of trees. Such crown fires are extremely difficult to fight, often leading to fires of much larger scale and higher severity than those that occurred before the settlement of our forests. Large-scale crown fires in the ponderosa pine forest may then become stand-replacement fires, whereby all the trees in a stand are killed. This leads to large stands of highly favorable woodpecker habitat in the short term. However, these conditions deteriorate rapidly, with successive years of storms toppling remaining snags, leaving a grass-and-shrub understory and a forest that takes centuries to redevelop to its pre-burn state. The 1990 Aubrey Hall burn between the city of Bend, Oregon, and the Deschutes National Forest epitomized these stand-replacement fires occurring across western pine forests.

The U.S. Forest Service lists the Lewis’s Woodpecker as a sensitive species both in the Northwest Region and locally in Deschutes. DNF wildlife biologist Lauri Turner reported that a regional conservation assessment is underway, one which the agency will then use to assess future projects on the forest to consider any impacts on the bird’s habitat. Turner said that the Forest supports the efforts of the East Cascades Bird Conservancy (ECBC) to provide and monitor nesting boxes for the Lewis’s Woodpecker.

“The volunteers are providing unique information that we don’t have any means of collecting on our own and providing innovative ideas on potential solutions to a specific problem,” she explained.

Deschutes currently manages extensive swaths of ponderosa pine forest for the region’s iconic White-headed Woodpecker, a resident species that is far more widespread than the Lewis’s. Although they are not managing burns specifically for the Lewis’s Woodpecker, biologists recognize that burns provide future habitat for the species. According to Turner, White-headed management priorities are backed by the types of studies the forest needs for the Lewis’s.

“We know more about the White-headed Woodpecker,” Turner noted. “We work in White-headed habitat more often and we have more scientific information than we do for Lewis’s to help guide us in our prescriptions. That’s what the conservation assessment is dealing with—trying to gather information to determine where to utilize our resources.”

The ECBC project is a model for volunteer-based citizen science efforts, but the Forest Service requires more rigorous science on which it can base future management plans. Turner hopes that efforts by ECBC volunteers will help fill in large gaps in scientists’ knowledge of how Lewis’s Woodpeckers utilize both burned and “green” habitats in Deschutes.

Research biologist Victoria Saab coordinates the “Birds in Burns” program out of the U.S. Department of Agriculture’s Rocky Mountain Research Station in Montana. Saab explained that Lewis’s Woodpeckers evolved as wanderers, moving from one burn to another to exploit the varying availability of aerial insect prey among burns of different ages. Because of this nomadic behavior, she emphasized that conservation efforts for the species should address populations on a regional scale rather than those within a single burn perimeter. But she acknowledged that Lewis’s Woodpeckers are “hard to monitor long-term when it’s such a dynamic system and they occupy ephemeral habitats.”

The Washington, D.C.-based American Bird Conservancy (ABC) extends its support throughout the western hemisphere, and ABC’s Pacific Northwest coordinator Bob Altman has provided technical support for the ECBC project from the beginning. ABC has also helped with publicity, publishing articles in Bird Conservation magazine, including a feature on ECBC volunteer leader Diane Kook, whom it called an “unsung hero for bird conservation.”

Altman explained that the ECBC project could open the door to studies of greater depth, allowing researchers to statistically evaluate habitat relationships and various factors that contribute to successful use of nest boxes. While all parties await further research, however, the Lewis’s Woodpecker continues to prove that it certainly will use the nest boxes Kook’s team provided.

“We are trying to spread the technique to properties where we are working on habitat restoration projects,” explained Altman. The organization has been working with private landowners throughout the Northwest on its ponderosa pine cavity-nesting bird program.

“We have been creating snags and then using nest boxes until the snags are suitable for nesting,” Altman said. Albeit on a smaller scale than the “parent” project, ABC has installed more than a dozen boxes over three properties in the region.

“The ECBC uses boxes in a burn where Lewis’s Woodpecker already occurred,” Altman noted, “and we’re using it as follow-up to habitat restoration.”

Altman pointed out an unusual conundrum with the Lewis’s Woodpecker, a species that exhibits declining populations despite its selection of versatile nesting habitats, breeding in riparian cottonwood forest, oak-pine woodlands, and burned ponderosa pine forest.

“The bottom line is the loss of snags within those habitat types,” he explained. Even though burns provide snags for a short period, over successive years after a fire snags are lost due to removal or attrition.

Altman also cautioned that the use of nest boxes should not be considered a panacea for a greater conservation problem.

“We have to recognize these things as short-term tools,” he said. “In the interim, we can maintain or improve populations using nest boxes, but the real goal is to have more snags in the landscape.”

USDA research biologist Victoria Saab echoed Altman’s sentiments about the importance of snag availability, adding that the presence of other woodpecker species is also required for Lewis’s Woodpeckers to thrive after a fire.

“If there are strong excavators in the area, (the Lewis’s Woodpeckers) will use already existing cavities,” she said. “Snags created before the fire are really important in the first couple years after the burn, because they are already decayed to the point where they could be excavated.”

Altman explained that the ECBC project will help “maintain local populations a little longer than they would naturally occur. Normally, snags will reach a minimum threshold and the Lewis’s Woodpecker will move on,” he said. “This project will allow continued reproduction and more birds in local populations, buying us a little bit of time and building up the population a little more, supporting the future occupation of other sites.”

“Prey availability may become a limiting factor at some point,” Altman added, “but now that we know that Lewis’s Woodpeckers will use boxes, we may be able to bring back populations using nest boxes as a short-term tool for conservation.”