A Decade of U.S. Air Force Bat Strikes

From 1997 through 2007, 821 bat strikes were reported to the U.S. Air Force (USAF) Safety Center by aircraft personnel or ground crew and sent to the National Museum of Natural History, Smithsonian Institution, for identification. Many samples were identified by macroscopic and or microscopic comparisons with bat specimens housed in the museum and augmented during the last 2 years by DNA analysis. Bat remains from USAF strikes during this period were received at the museum from 40 states in the United States and from 20 countries. We confirmed that 46% of the strikes were caused by bats, but we did not identify them further; we identified 5% only to the family or genus level, and 49% to the species level. Fifty-five of the 101 bat-strike samples submitted for DNA analysis have been identified to the species level. Twenty-five bat species have been recorded striking USAF planes worldwide. The Brazilian free-tailed bat (Tadarida brasiliensis; n = 173) is the species most commonly identified in USAF strike impacts, followed by the red bat (Lasiurus borealis; n = 83). Bat strikes peak during the spring and fall, with \u3e57% occurring from August through October; 82% of the reports that included time of strike were recorded between 2100 and 0900 hours. More than 12% of the bat strikes were reported at \u3e300 m above ground level (AGL). Although$825,000 and \u3e50% of this sum was attributable to 5 bat-strike incidents. Only 5 bats from the 10 most damaging bat strikes were identified to the species level, either because we did not receive remains with the reports or the sample was insufficient for identification

Identification of Batstrikes (Poster)

Identification of fragmentary evidence such as hairs, bones, and claws that have been recovered from United States Air Force (USAF) aircraft has been undertaken by the Biological Survey Unit (USGS) for the last 5 years. The results of these investigations may be useful in preventing future damaging batstrikes. Examination of batstrikes may also provide valuable information to the scientific research community about patterns in bat migration, flight altitudes, and times of flight. Positive identifications are made by comparing unknown samples with the collection of museum specimens housed in the Smithsonian Institution’s National Museum of Natural History. Macroscopic characters such as color, texture, and size help narrow the possibilities, while microscopic features such as patterns seen in scales and medulla of the hair can be used to distinguish major groups of bats. All but eight of the 70 reported wildlife strikes during this reporting period were identified to species level. The Brazilian free-tailed bat (Tadarida brasiliensis) was struck 23 times, while the red bat (Lasiurus borealis), was identified from 15 strikes. The hoary bat (Lasiurus cinereus) was only identified in 10 strikes although this large species of bat caused the most damage to USAF aircraft. Damage reported from these strikes by the USAF totaled over $50,000. One strike alone caused over$21,000 in damage. An examination of damage caused by different species indicates that Brazilian free-tailed bats caused approximately $12,000 while the second most commonly hit bat, the red bat, caused no damage, even though several strike reports documented multiple impacts with these bats. These results indicate that body mass plays a large role in damages incurred by collisions with these bats

BAT STRIKES: PAST, PRESENT, AND FUTURE

All but a few North American bats are insectivorous and weigh less than 35 g, but this diverse group of mammals also contains species with wingspans up to 2 meters and weighing a kg or more. Even small-bodied bats can cause considerable damage when encountered in swarms. When aircraft head into new territory and encounter strikes, the ability to identify the species of bat struck is paramount to preventing future strikes. Identifications of bats from fragmentary evidence are made by comparing samples recovered from aircraft with specimens housed in the Smithsonian Institution’s National Museum of Natural History. This collection, worldwide in scope, is the largest collection of mammal specimens in existence. The species of bat most frequently identified in U.S. Air Force aircraft strikes is the Brazilian free-tailed bat, Tadarida brasiliensis (38%). Tree bats, which include the red bat, Lasiurus borealis (19%), Seminole bat, L. seminolus (7%), and hoary bat, L. cinereus (13%), along with strikes identified only to the genus level, collectively comprise 44% of identified bat strikes. The information obtained from these identifications has already greatly enhanced our understanding of when and where bats are flying. The data associated with these aircraft strikes in respect to date, time, location, and altitude of flight may also provide important insights for other projects, such as the development of wind energy resources

A Curious Pellet From a Great Horned Owl (\u3c/i\u3eBubo Virginianus\u3c/i\u3e)

One of the traditional methods of determining the dietary preferences of owls relies upon the identification of bony remains of prey contained in regurgitated pellets. Discovery of a pellet containing a large, complete primary feather from an adult, male Ring-necked Pheasant (Phasianus colchicus) prompted us to examine in detail a small sample of pellets from a Great Horned Owl (Bubo virginianus). Our analyses of feather and hair remains in these pellets documented the presence of three species of birds and two species of mammals, whereas bones in the pellets represented only mammals. This finding indicates an important bias that challenges the reliability of owl pellet studies making use of only osteological remains