Transmitter data confirm that the unusually warm spring is bringing loons back to Minnesota almost three weeks earlier than usual.
At least six of 29 loons tagged with satellite transmitters had returned to their breeding lakes in Minnesota as of last Wednesday, the Department of Natural Resources said Monday. The earliest arrival returned to Big Mantrap Lake in northern Minnesota on March 29.
Most of the tagged loons left Minnesota in October and spent about a month on Lake Michigan before departing for the Gulf of Mexico in early December. Carrol Henderson, supervisor of the DNR's Nongame Wildlife Program, said that until scientists started using the transmitter technology in recent years they had no idea that most Minnesota, Wisconsin and Michigan loons "stage" on Lake Michigan before flying south to the Gulf.
The research is funded partly by donations to the Nongame Wildlife fund on Minnesota income tax forms.
Lori Naumann, spokeswoman for the Nongame Wildlife Program, said some of the same funding is also being used in an ongoing study on whether the 2010 Gulf oil spill has affected Minnesota's official state bird. She said it's still too early to know, partly because young loons that fly south spend two summers on the Gulf Coast before returning to Minnesota. It's not known how many died because of the spill and how many just haven't come back yet, she said.
The transmitters will be useful in gauging the impact on loons of the oil and the dispersants used to break up the spill because loons sink when they die. The telemetry can help scientists recover those carcasses for testing, she said.
Researchers tagged four Minnesota loons in 2010, 30 last year, and plan to tag 30 more this year, Naumann said.