Owls adjust to new burrows Published Nov. 26, 2010 By Megan Just 452 AMW Public Affairs MARCH AIR RESERVE BASE, CALIF. -- For years, the southwest corner of March Air Reserve Base has been everything a burrowing owl could want. There are ready-made underground tunnels, courtesy of the base's ground squirrel population, and groundskeepers mow the grasses in the area, which helps the little owls keep their vigilant lookout for food and predators from atop their stilt-like legs. But soon, the remote corner of base will be anything but a haven for burrowing owls. On Dec. 2, the 452nd Civil Engineering Squadron will break ground for a 28,000-square foot indoor firing range, directly above the owls' underground nest. The new range will contain 28 small arms lanes with seven of the lanes being suitable for the firing of heavy weapons. It will replace the aging, 19-lane outdoor range March Airmen currently use. "The lifespan of an average range is 20 years. Our range was constructed in the 1940s," said Master Sgt. Daniel McDow, 452nd Security Forces Squadron noncommissioned officer in charge of combat arms, who worked closely with the civil engineering squadron to design the new range. The outdoor firing range is located on property that has not been inside the confines of the base since the Defense Department's Base Closure and Realignment Commission downsized the base in 1996. The base's 4,000 reservists use the range for periodic and predeployment small arms qualifications. Airmen from Los Angeles Air Force Base use the range, as well as Army reservists and local law enforcement agencies. With the arrival of a new active duty associate squadron in October, the demand for the range is even greater. "(The current range) is an outdoor range where the bullets are being stopped by a dirt berm," said Maj. John McDowell, 452nd Security Forces Squadron commander. "The new range will trap the bullets and filter the air so there won't be any contamination going outside the facility. This facility will better prepare our troops deploying to increasingly hostile combat zones and will vastly improve our current training capability." THE OWLS Burrowing owls are designated as a Species of Special Concern in California and are a National Bird of Conservation Concern through the U.S. Fish and Wildlife Service. The owls are listed as threatened in Mexico, endangered in Canada and are protected by international treaty through the Migratory Bird Treaty Act of 1918. In 2003, Riverside County adopted a multiple species habitat conservation plan that includes the burrowing owl. "The plan requires all new construction projects to survey the site to determine if there are burrows or suitable owl habitat," said Gearld Haas, acting natural resource manager with the 452nd Environmental Management Flight. "In this case, we already knew we had owls and that there was an active burrow on site." Haas contacted raptor ecologist Dr. Jeffry Lincer who specializes in burrowing owl biology and management to advise the base on the best way to mitigate the impact of the firing range. "It may seem seem like a lot of effort for two little owls, but the protection measures we're taking will benefit the entire owl population on base," he said. "The base may be surrounded by a fence, but ecologically speaking, we are not isolated from the land around us." Dr. Lincer is the research director of Wildlife Research Institute, a non-profit organization based in Ramona, Calif., that Lincer co-founded in 1997. He is also helping the base manage a parcel of land the base set aside as a relocation site for the owls. "The owls are declining in many of the western states," said Lincer. "They have declined tremendously in all of the coastal counties in California and many of the counties in the interior." According to an article Lincer published in 2007 with Dr. Peter Bloom, in San Diego County, burrowing owls have decreased 90% in the last 25 to 30 years, which is typical of a coastal county. Lincer, who previously conducted an inventory of the owls on base in 2004, visited the base in March to conduct an initial assessment of the firing range site and the relocation site. "When I arrived on the site, I found a pair of burrowing owls in an abandoned California ground squirrel burrow. They appeared to be a mated pair," he said. "The new site was very similar. . .There was evidence of burrowing mammals and there were plenty of beetles, grasshoppers and other insets for prey." Although the relocation site is slightly closer to the runway than the former site, Lincer said there is not an increased bird aircraft strike hazard, where birds caught in an aircraft's engine can jeopardize the aircraft and crew. He said burrowing owls have high nest site fidelity, which means the owls tend to stay in a particular place once they have nested there. CONSTRUCTING NEW BURROWS Because burrowing owls nest between February and August, Lincer recommended waiting to translocate the owls until the late fall. He returned to the base in early September with a team of four volunteers to construct six burrow clusters in the relocation area. Using a backhoe, Lincer and his crew dug three-foot holes in which they placed plastic totes to serve as nesting boxes. They used drainage pipes to create two, eight-foot tunnels leading from each box. The volunteers and environmental flight staff filled in the holes and Lincer forced the ends of the piping into concrete blocks to protect the entrances against accidental crushing. Lincer said the base probably could have taken fewer mitigation measures, but the fact that they didn't speaks highly of the base's dedication to protecting the environment. "Providing for an active translocation, including the preparation of a recovery site, substantially increases the chance of the owls surviving and breeding, and therefore, contributing to future generations of owls in the population on base," he said. "This commitment to natural resources is not only admirable, but necessary by many individuals and agencies if the owl is to survive," Lincer continued. "Military bases have great potential to properly manage and support these owls and many other species of wildlife. This is a wonderful example of doing things right." MOVING DAY The final step in the firing range mitigation was the translocation, which Lincer scheduled to occur two weeks before the groundbreaking for the new firing range. On Nov. 16, he carefully trapped the two owls with bow nets and moved them to a 6-by 8-foot predator-proof cage above the primary entrance to the owls' new burrow. He blocked the second entrance to the burrow, which will ensure the owls remain in the area to adjust to their new home. Because the owls will not be able to hunt, Haas will feed the owls a diet of three mice per day. A solar-powered electric fence in a 30-foot square around the cage prevents ground predators like coyotes from harassing the birds. By the time Lincer releases the owls in five to six weeks, the construction project will be underway and the noise and activity at the construction site will discourage the owls from returning to their old home. Lincer hopes the owls will stay in the burrow, or nest nearby, but he said the ultimate measure of the success of the translocation is "if they're permanently removed geographically from the nesting site." He will monitor the owls weekly while they remain in the hack cage and, after, will continue to periodically track the owls and the occupancy of the other six burrows. PRESERVING THE SPECIES The two owls that were translocated were the only burrowing owls on the firing range site and are now the only owls at the relocation site. However, it wasn't always this way. In 2008, Haas recalls seeing 12 owls and owlets at the firing range location. Additionally, in 2004, Lincer documented more than 20 owls on the relocation site. Lincer said there could be a number of reasons for the this, but he speculates the reasons could be a change in the land use around the sites, a decrease in the prey population or a decrease in available burrows because of a decrease in the ground squirrel population. He said a comprehensive survey for comparative purposes would be needed to make an accurate determination. "Just because there's been a decrease in one small area doesn't mean there is a decrease across the entire base," he said. "If there was a decrease, the likelihood of an increase or a return in original population would depend on what caused that decrease and if it was something we could control or manage." Lincer and Haas hope the small preserve at March Air Reserve Base will provide a model the base can learn from as well as provide a habitat for more pairs of burrowing owls. "We, as a human species, we're simplifying our ecosystem every time we manage to make another species extinct," he said. "When we do that, it takes with it a small part of the web that we are a part of. You can only take so many strands out of a web before it collapses." Unlike other owl species, which are nocturnal, burrowing owls are most active at dawn and dusk and can often be seen outside their burrows during the day. For this reason, Lincer said people feel a special connection to the tiny, "charismatic" owls, with their striking yellow eyes. In taking action to mitigate the primary threat to the owls--loss of habitat--the base is helping to preserve this unique species for the next generations.