Rats to be attacked from the air

  • Nov. 30, 2012 5:00 p.m.

By Jane Wilson–Gwaii Haanas will be conducting the first aerial rat eradication in Canada next fall, in the next phase of its $1.6 million rat eradication program.The SGin Xaana Sdiihltl’lxa – Night Birds Returning initiative is ?designed to protect nesting seabird habitats and restore the ecology of? small island ecosystems, which are negatively affected by the loss of the seabirds. Dr. Carey Bergman, Gwaii Haanas terrestrial ecologist says that people ?often don’t realize that the problem does not just effect Gwaii Haanas, as birds that nest on the islands travel as far away as California and Japan. “The rats are having a global impact,” she said.GwaiI Haanas completed the first part of its rat eradication plan ?in August 2011 when Gwaii Haanas staff used baited traps to eradicate rats on the Bischof and Arichika Islands. Dr. Bergman said that phase of the project was successful so far and there are no further signs of rats on the islands, although they won’t declare complete success until two years of monitoring are completed.The next phase of the plan is to eradicate rats on Faraday and ?Murchison Islands to restore their ecology and create a buffer zone to keep ?rats off Ramsay Island, which Dr. Bergman described as “a globally significant seabird colony.”Gwaii Haanas staff will be dropping rodenticide made of pressed grain and a rat toxicant over 700 hectares of these two islands. Dr. Bergman said this method was chosen because there is a much greater area to cover during this eradication and ?because the rats on Faraday and Murchison are black rats, rather than? the Norway rats on the Bischof islands. Black rats are a climbing rat,?which the Norway rat is not, so the black rats have a denser population ?and cause more damage. It is crucial that 100 percent of the rats eat the bait,?otherwise success will not be achieved.The grain-based pellets will break down in three to six weeks, she said. The timing of the operation has been carefully chosen to minimize the impact on other species. By doing the eradication in September and October, ravens and eagles are expected to be eating salmon from streams and seabirds will? be out to sea.Dr. Bergman’s work on the project will be monitoring the ecosystem recovery. Staff install seabird recording devices and remote cameras into affected areas to trackanimal populations. According to her, when you listen to an island with rats it is totally silent but an island without rats will have “an incredible cacophony of birds.”While the rats are a significant problem in Gwaii Haanas they are not as prevalent as has been recently reported, she said, as they have only been found on 18 of the 50 islands park’s staff have checked. The majority of the islands are still rat free.