Date of this Version
Proceedings of the 15th Wildlife Damage Management Conference. (J. B. Armstrong, G. R. Gallagher, Eds). 2013.
Wetlands constructed for the treatment of urban wastewater effluent have gained world-wide popularity in recent decades. Placement of such wetlands near airports however, is strongly discouraged by the U.S. Federal Aviation Administration, other national airport authorities, and the International Bird Strike Committee because they attract birds that may increase strike risks for aircraft. Despite recognition of this and other wildlife hazards to aircraft and efforts implemented to limit such land-use activities near airports, validated methods are still urgently needed to mitigate wildlife hazards on or near air-ports because bird populations and bird-aircraft strikes in the U.S. and elsewhere around the world persistently trend upward. The city of Augusta, Georgia USA designed and developed 144 ha of wastewater treatment wetlands on land adjacent to its Regional Airport at Bush Field during 1997–2002. In December 2001, we began temporal and spatial monitoring of bird activities in this area, recording species, their numbers, and flight characteristics. Within 2 years of completion, the wetlands, dominated by giant cut-grass (Zizaniopsis miliacea) and cattails (Typha spp.), served as a nighttime roost for millions of migratory blackbirds (family Icteridae) that crossed the airfield in massive flocks daily at sunrise and sunset during November–March. Beginning in December 2005, we investigated the efficacy of habitat alteration techniques to displace the blackbirds, including the use of airboats to mechanically crush wetland vegetation in portions of the treatment wetlands. The results of this method were highly significant, with far fewer blackbirds landing in crushed-vegetation areas than in uncrushed areas. Beginning with the fall of 2008, this vegetation-crushing technique was implemented annually for the entire wetland system; long-term post-crush bird monitoring indicated that blackbird roosting within the wetlands was almost non-existent and blackbird activity around the airport was reduced by about 2 orders of magnitude. The ability of the wetland vegetation to process wastewater effluent was not negatively affected by vegetation alteration. This work successfully demonstrated that with thoughtful wildlife hazard management, including the consideration of novel techniques, it may be possible to mitigate large-scale undesirable wildlife attraction associated with certain land-use activities. Importantly, this success was accomplished through non-lethal means, using a relatively simplistic habitat altering technique. Throughout the succession of these events, careful monitoring of bird-aircraft strikes, bird numbers and their movements, and an unbiased evaluation of bird mitigation efforts formed the foundation of the success that was achieved.