Tuesday, January 13, 2009

Eradication of feral cats at Wake Atoll

Source: Atoll Research Bulletin, no.560 (Nov.2008)
"Feral cats (Felis catus) were introduced at Wake Atoll, (19°18' N, 166° 38' E)
in the 1960s as pets and probably to control rats on this U.S. military base in the North Pacific Ocean. After base-downsizing in the 1970s, feral cats became a noticeable problem. Hunting and trapping to control their numbers has been sporadic over time but began seriously in 1996 and continued through 2002, during which time about 200 cats were removed. The eradication effort began in July 2003 and by January 2004 another 170 cats had been removed. During visits from late 2004 to 2007, two feral cats were seen but no cat reproduction was detected. Bird populations responded quickly to the release of predation: Masked Boobies (Sula dactylatra) increased from three breeding pairs in 1996 to 25 by 2007; the Brown Booby (S. leucogaster) population rose from 73 nests in 1996 to 162 in 2003. Wedgetailed Shearwaters (Puffinus pacificus) recolonized around 1998 and populations expanded to form at least three colonies with individuals in numerous locations around the atoll. Gray-backed Terns (Onychoprion lunata), not recorded breeding on the atoll since the 1980s, began nesting in two new sites, and Great Frigatebirds (Fregata minor),which had not been recorded nesting since the 1960s, renewed reproductive efforts in 2005. Laysan Albatross were finally successful in rearing a chick and appear to be increasing. Due to feral cat removal and wet weather, Pacific Rats (R. exulans) greatly increased. Current rodent control effort was less effective than it should be because hermit crabs (Coenobita perlata) ate the bait before the rats did. A bait station model design to exclude crabs was designed and tested. The island managers continued to control rats at Wake around housing areas, and rodent populations have declined since their peak following cat eradication."