At the beginning of 2006 when we started this web site I thought I would have to scramble to find something to post on a weekly basis. I’ve been holding some stories back for a “rainy” day. Hmmm…that rainy day is nowhere on the horizon. So here’s an article created in April about how one of our members manages rattlesnakes and raptors on the job.
There are rattlesnakes two feet away from me. They are curled inside a wooden box in the bed of a pickup truck ready for a new destination. Yes, the back wall of the pickupâ€™s cab is between me and the box of snakes but I know these venomous occupants are there. I volunteered to help with a migratory bird count, not sit next to reptiles. But these reptiles are part of the environment that is under the management of the Natural Resources Manager at Dyess AFB, Mr. Kim Walton. It is his responsibility to ensure wildlife and aircraft don’t meet on the ground, during takeoffs or landings, or in the air.
So how does he balance the requirements of the Air Force with the needs of wildlife such as rattlesnakes, rodents, rabbits, or raptors?
It all starts with grass. Back in the 1970â€™s a team at Kirtland AFB, New Mexico, experimented with different ways to discourage flocking birds from airfields. They discovered that if the grass was maintained at a height of 7 to 14 inches this height was too short for rodents to comfortably hide in. If there were no rodents in the grass the large hawks would look for them in their proper habitat, tall grass. For this reason there are areas on base (far from the airfield) that are not mowed. Mice, rats, and rabbits prefer the taller grass and it doesn’t take long for the hawks to figure out where to look for the rodents.
Keeping the grass between 7 and 14 inches also prevents the grass from going to seed. Rodents eat plant seeds and there are many passerines (song/perching birds) that are seed eaters. If their food is eliminated around the airfield they, too, will go elsewhere to look for food. Even small birds have the ability to cause damage to aircraft. In September, 2005 a DC-10 landing at Forth Worth Meacham International Airport ingested about 15 to 20 pigeons in the # 3 engine. An engine change was required and the aircraft was out of service for one week. Cost estimated at $1.5 to $2 million. Starlings are known as “feathered bullets” having a body density 27% higher than Herring Gulls. Starlings are now the second most abundant bird in North America with a late summer population of approximately 150 million birds. Luckily, Starlings are not an issue for Dyess.
The most problematic birds for Dyess are the small swallows and meadowlarks because they are so numerous and short grass contains insects, the birds’ favorite food. Sometimes Turkey Vultures are spotted soaring in the airspace above the runways. If a cow has expired on land adjoining the airfield, vultures will be attracted to the carrion. A phone call to the landowner is usually all it takes to remove the carcass thus eliminating the vultures.
Neither are ducks, geese, or cranes problematic for Dyess. There is no large body of water on base to entice wintering waterfowl. If ducks flocked in such numbers as to cause concern, Kim has a depredation permit to eliminate the problem. However, this drastic solution hasnâ€™t been necessary because Kim manages the habitats correctly. The Air Force also developed a bird avoidance model using data collected from over thirty years of Christmas Bird Counts, Breeding Bird Surveys, and other datasets. This data along with Nexrad radar identifies migratory flocks of birds and the Air Force notifies pilots to adjust their route or ceiling to avoid collisions. Last December I accompanied Kim to the airfield and we watched newly arrived Northern Harriers course over the short grass hunting for rodents. Two weeks later during the Christmas Bird Count, none could be found. By eliminating the rodents and by eliminating suitable perching sites by installing bird spikes on utility poles or other structures, Kim sends a “no trespassing” message to all raptors that try to stay. Like most of us, the birds prefer to hang out where food is abundant and the seating is comfortable.
But what if some of the smaller rodents find the short grass suitable? What if some of the grass goes to seed? This is where the rattlesnakes enter the picture. Rattlesnakes discovered near base housing are relocated to the shorter grass around the far west side of the airfield just for rodent control. It won’t take long for the snakes to find their furry snacks.
There were over 5,100 bird strikes reported by the U.S. Air Force in 2005 (Dyess reported none that year). When strikes occur, the birds’ remains are sent to the Feather Identification Laboratory, National Museum of Natural History at the Smithsonian Institution in Washington, D.C. There Dr. Carla Dove (no pun intended) and her team identify the species of birds involved in the collisions, even if all that is collected is a little bit of blood. This is forensic ornithology at its best. It is important to report all strikes even if no damage occurs to the aircraft. Only after identifying the species can habitat managers design better schemes to discourage birds’ use of airfields, and the results help aircraft manufacturers design aircraft that can withstand the impact of bird collisions.
Now that you know rattlesnakes are an important tool for Mr. Walton to reduce bird/aircraft collisions, you might find it amusing to know the name the Air Force gave to this set of guidelines: Bird/Wildlife Aircraft Strike Hazard guidelines or “BASH” for short. I always knew snakes were good for bashing, just didn’t know they would enjoy it.
Pictures of a rattlesnake den, and re-enactment of a hunt, capture, and containment are now on the web.