Field Updates
June 11, 2010
Field biologists are back at Rat Island this month, and so are the birds! This is the first year in which measurable increases in native bird populations are expected – 2009 presented the first full rat-free breeding season in more than 200 years. It’s also the fourth consecutive year in which biological monitoring has occurred on the island — this includes standardized surveys for landbirds, shorebirds, seabirds, waterfowl, game birds, birds of prey, and intertidal and vegetative communities. A second visit in late August finishes invasive rat-detection monitoring.
The eagles and gulls that were collected on Rat Island last summer and tested for rodenticide residue all were positive. Therefore, we know the birds were exposed, and they likely died from rodenticide exposure. This was not expected and we are deeply saddened. We have commissioned an independent review of our procedures to understand what happened, and how we can prevent this sort of non-target mortality from occurring again.
We remain cautiously optimistic that the island is free of rats, and expect a full recovery of native habitat and species assemblages.
July 1, 2009
The U.S. Fish and Wildlife Service has received laboratory results on an initial group of bird carcasses collected on Rat Island in late May and Early April. Examination of the livers of two bald eagles, two glaucous-winged gulls, one peregrine falcon, and one rock sandpiper all tested positive for the rodenticide brodifacoum. We are in the process of analyzing all of the viable bird remains and tissue samples collected, in order to more fully understand the cause of mortalities and more effectively plan future operations in the Aleutians. Results will be released when they are available. In addition, soil and water samples were collected, and will be analyzed to more fully understand the potential movement of the rodenticide into, and degradation from, the ecosystem.
No living rats have been detected on the island, and the Service and its partners are cautiously optimistic that all of the rodents have been eradicated. If another year passes without a rat sighting, the team can declare the island rat-free for the first time in 229 years.
Early signs of positive ecosystem change were documented; nests and chicks of black oystercatchers, glaucous-winged gulls, and common eiders were observed, in addition to a first-time record of breeding seabirds on an offshore rock previously inhabited by rats. Reports from the camp indicate that all bird species on the island except eagles are present in numbers similar to those found during pre-treatment surveys. Falcons and gulls were observed successfully nesting on the island, and several observations of live adult and sub-adult eagles were made. Species such as murrelets, storm-petrels and puffins are expected to recolonize the island in the coming years if the rat eradication is proven successful
A survey team dispatched to the island this May encountered a higher-than-expected number of carcasses of two non-target species. Biologists found 213 glaucous-winged gulls and 43 bald eagles. The team of biologists has reported no evidence of ongoing mortality on the island.
The Service has no evidence that new mortalities have occurred. The partnership intends to dispatch a second team in early August to continue monitoring on the island.
June 11, 2009
After more than two weeks of intensive field monitoring on Alaska’s Rat Island, biologists have found no sign of the invasive rats that have decimated native bird populations. The same studies have documented that several bird species, including Aleutian cackling geese, rock ptarmigan, peregrine falcons, and black oystercatchers are nesting on the island.
The survey team also collected a higher-than-expected number of carcasses of two non-target species. Biologists have found 157 juvenile and 29 adult glaucous-winged gull carcasses and a total of 41 bald eagle carcasses. About 75 percent of the eagle carcasses appear to be juvenile birds.
Fewer than ten rat carcasses have been found. This is consistent with the project’s expectations. Based on field trials in 2006, the team expected that 90 percent of rats would return to burrows.
The cause of the bird deaths is unknown. Bird carcasses and tissue samples have been sent to the National Wildlife Health Center laboratory in Madison, Wis. The U.S. Fish and Wildlife Service has expedited the tests to confirm the cause of death of the birds. Tests are expected to be complete by mid-June.
Biologists established a monitoring camp on Rat Island on May 26 and reported the results of its surveys June 10. The carcasses and tissue samples were picked up by the R/V Tiglax, a U.S. Fish and Wildlife Service research vessel on June 10. All collected samples are to be shipped to the National Wildlife Health Center from Adak, the nearest port.
October 13, 2008
The Rat Island seabird restoration crew safely returned to Alaska Maritime National Wildlife Refuge headquarters in Homer aboard the 120-foot Tiglax research vessel.
Because the team completed its mission ahead of schedule, the Rat Island project was able to donate about $9,000 in food to the Homer Food Bank.
October 6, 2008
The Rat Island conservation partners have completed the entire bait application! All the bait has been broadcast, and now the team begins its two years of monitoring to determine the success of the eradication. The excellent planning by the entire team allowed the field team to take advantage of the excellent weather on the island the last two weeks.
The team will continue to demobilize the field camp today, they expect that job to be completed by 1500 or 1600 hours this afternoon at which point the helicopters will begin their return trip to Homer. The R/V Tiglax will pull the field team off the island today, and return to Adak this afternoon or Tuesday morning.
October 3, 2008
Good weather persists on Rat Island, and the seabird restoration team continues to make great progress. The first bait application is complete. Bait was applied by hand to freshwater exclusion zones around the island’s lake complexes on Wednesday and Thursday. This time-intensive process was conducted to prevent bait from entering the island’s freshwater systems. Also on Thursday, the team began the second application on the mountains in the center of Rat Island and baited the small islet off of Ayugadak Point on the southeast corner of Rat Island. This islet is used by Steller sea lions and great care was taken to minimize disturbance to the sea lions during baiting operations.
On Friday, the team will take a day to assess the progress made and review all application data. The second bait application will occur on Saturday and Sunday on the inland and coastal sections. Once the second application is finished, the baiting operations will be complete and the team will begin to demobilize and prepare for their return.
October 1, 2008
The continuing good weather on Rat Island has allowed to team to continue to make great progress. The remainder of Rat Island, including sea stacks offshore, was baited on Tuesday, September 30. A small islet offshore of Ayugadak Point that is used as a haulout by Steller sea lions is scheduled next. An on-site observer is required when baiting on or near areas used by Steller sea lions. Additional crew, including the observers, are arriving aboard the U.S Fish & Wildlife Service research vessel, the M/V Tiglax, this morning (October 1). The Tiglax crew will conduct the pre-application sea lion count, and baiting will occur either this afternoon or tomorrow morning. The low-pressure system that appeared to be moving in has moved off, and good weather is expected through the weekend. If good weather continues, the second application will begin in the mountain area Thursday or Friday, October 4 or 5. If the good weather holds, the rest of the island will receive the second treatment over the weekend or early next week.
Sept. 29, 2008
Today marked the second day of seabird restoration operations on the island, and it's also the first sunny day. When the sun came up, the entire mountain range in the center of the island was clear. The helicopters were in the air by 11 a.m. and were able to spread bait on the mountain range (the project's first priority area) and on nearly 1,850 hectares overall. This amounts to nearly two-thirds of the island.
A promising weather forecast for Sept. 30 suggests that all of Rat Island proper should be baited by day's end. The team expects to put bait on the small islet off the southeast point of Rat Island (Ayugadak Point) on Wednesday. This would complete the first bait broadcast.
A second application is planned to help ensure the project's success. Another weather front is moving in (there always is in the Aleutians) expected to hit on Thursday, Oct. 2. That is expected to last three days. The second round of baiting may start as early as Monday, Oct. 6, but it is far too early to say so definitely.
"This is way ahead of schedule, and is a very positive sign for the entire project," according to Steve MacLean, director of The Nature Conservancy's Bering Sea program. "To have this level of success early in the project is incredible. This is a testament to the hard work that the whole partnership - the Conservancy, Island Conservation, and the Alaska Maritime National Wildlife Refuge - has put into restoring seabirds."