Bird Strike Committee Proceedings


Date of this Version

May 1999


Wildlife-aircraft collisions caused an estimated $114 million of damage annually to civilian aviation aircraft in the United States between 1993 and 1995 (Cleary et al. 1996). Significant damage to aircraft and crashes may result from the ingestion of one small bird (Cleary et al. 1996). Collisions that do not cause physical damage to aircraft often result in costs related to aircraft downtime while structural inspections are completed. Despite heightened awareness of the hazards wildlife present to aircraft, strikes occur often and occasionally have catastrophic results. The yellow bittern (Ixobrychus sinensis) is a common breeding bird throughout the western Pacific. Yellow bittern threats to aviation safety have not been previously documented, but are presumably present at airfields throughout the tropical Pacific. Bitterns feed primarily on lizards and insects and forage in open grassy areas that are typical of most airfields. Bitterns are year-round residents on the island of Guam in the Mariana chain, and are the only native bird commonly breeding on the island. Bitterns are widely distributed throughout Guam and are abundant around the few remaining freshwater wetlands on the island. Bittern breeding occurs all year, although a peak in activity may occur between January and June (Jenkins 1983). Common nest sites on Guam include wetland vegetation, palm trees, ornamental shrubs, and ground nests in dense grass. Nests and foraging sites are often located miles from water. The birds are generally solitary, but are occasionally observed in loose flocks of 30 birds or more. This paper summarizes the activities and results of an on-going management program dealing with aviation hazards created by yellow bitterns on Guam.