Wildlife-aircraft collisions (wildlife strikes) pose safety risks to aircraft and cost civil aviation over $390 million annually in the USA. We reviewed published studies to summarize findings on habitat management techniques that have shown potential for wildlife strike reduction. Habitat components that may attract wildlife to airports include food, cover, water, and loafing areas. Although maintaining tall herbaceous vegetation on airfields may reduce the attractiveness of loafing and feeding sites for some species of birds such as gulls, this strategy may also increase cover and food resources for other hazardous species. Thus, optimum vegetation height management strategies require further research and may be site-specific. Replacing attractive vegetation with less palatable vegetation has also been recommended, but studies with widespread application are lacking. Removal of ornamental trees and shrubs reduces cover for deer and small mammals and nesting sites for birds while also reducing availability of perches. However, exclusion techniques are also needed for reducing the availability of artificial perches and water. Despite more than 30 years of substantive discussion on the importance of these habitat management techniques, few reliable studies of the effectiveness of these techniques have been conducted under operational airport conditions.

Establishing the impact of double-crested cormorants on commercial farmed channel catfish production using visual assessments of cormorant GI tract contents is complicated by, first, the difficulty in distinguishing between partially digested fish of different species, and secondly, the possibility that the fish appearing in the diet have a natural source of origin. We analyzed the fatty acid profiles of selected game fish and farm-raised channel catfish to establish profiles that may allow for the application of this technique in establishing cormorant foraging patterns. We obtained for analysis farm-raised channel catfish from three commercial producers and one research facility. For comparison, we also collected channel catfish, gizzard shad, green sunfish, bluegill, and largemouth bass from natural waterways. A total of 12 sample groups were analyzed. Lipids were extracted using a modified Folch extraction and trans-esterified in 3N HCl in methanol. The resultant fatty acids were identified using gas chromatography/mass spectrometry. The relative mass percent distributions for the major fatty acids were calculated for each individual. A classification tree analysis was performed to identify groupings based on these individual fish distributions. These preliminary results have led us to conclude that it is possible to distinguish not only between farm-raised channel catfish and game fish in the diet of cormorants, but that it may be possible to identify the source of the farm-raised channel catfish in the diet. The management implications are that it may be possible, based on fatty acid analysis of GI tract contents of cormorants, to assess the actual impact of birds from a given roost or colony on a specific channel catfish producer.

We evaluated bird and small mammal use of two mowed (15 to 25 cm height) and two unmowed vegetation plots (40 to 88 ha) at John F. Kennedy International Airport (JFKIA), New York, in 1998 to 1999 to determine which management strategy would best reduce wildlife use of the airport. We counted more birds per 5- minute observation period in unmowed plots than mowed plots in both 1998 (9.0 versus 7.9) and 1999 (11.7 versus 8.6). Maximum vegetation height was greater (P<0.05) for unmowed areas than mowed areas after mowing commenced in 1998 and 1999 for each two-week monitoring period. In 1998 to 1999, vegetation density was also higher (P<0.05) for unmowed plots for 13 of 14 sampling periods. The species composition of vegetation differed (X2=20.54, df=3, (P<0.01) among mowed and unmowed plots. Mowed plots contained a higher percentage of grasses (81% versus 68%), and a lower percentage of forbs (16% versus 25%) and woody plants (1% versus 4%) than unmowed plots. Vegetation was generally sparse in both unmowed and mowed plots, a consequence of the poor, sandy soils on much of the airport. We captured 33 small mammals from three species in unmowed plots and 12 individuals of one species in mowed plots in 1999. Small mammal populations increased seasonally in unmowed plots, but remained constant in mowed plots over the same time period. We recommended JFKIA switch from the unmowed vegetation management regime in place since 1986 to a regime of maintaining vegetation mowed at 15 to 25 cm height. This management strategy should reduce bird and small mammal use of grassland areas at JFKIA. Further research should examine use of alternative vegetation types to improve ground cover and vegetation density at JFKIA while minimizing attraction to wildlife.