FINAL Common Loon Migration Update: May 20, 1999 Today's Report Includes: Loons Settling In Nesting Needs: Discussion of Challenge Question #9 Discussion of Challenge Question #10 Stopwatch: Discussion of Challenge Question #11 Sink or Swim: Discussion of Challenge Question #12 Take the Plunge: Discussion of Challenge Question #13 Have a Wonderful Summer! Loons Settling In Loon migration has pretty much finished up for the year. Just about all loons are back on territory, filling the north with haunting calls and flashes of brilliant color. A few stragglers are still arriving in the far north, but for the most part they've settled into nesting. Loons building nests, incubating eggs, and raising babies are fulfilling their responsibility to ensure the world a steady supply of loons forever. We wish them well! Nesting Needs: Discussion of Challenge Question #9 Loon in breeding plumage Photo: Woody Haage We asked you to give at least one reason that each of Dr. Judith McIntyre's "nest site criteria" are important for loons to raise young successfully: Clear water Good supply of fish Variety of bottom types and depths Nesting islands with a steep drop-off and a good view of the territory Quiet, protected places to raise chicks Clear water is essential for seeing fish and chasing them down. It takes a TON of fish to feed two loon adults and two chicks over the summer, so a good supply of fish is critical. The wider the variety of bottom types and depths, the greater the variety and supply of fish. A nesting island with a steep drop off allows loons to slip into the water quickly when confronted with a predator. The good view of the territory is important to detect predators before it's too late. The quiet, protected place is important so they can avoid predators to begin with. Discussion of Challenge Question #10 We asked when loon migration peaked this year. This graph shows the peak clearly. Stopwatch: Discussion of Challenge Question #11 "How might a careful, honest observer make a mistake clocking a loon's dive?" When a loon dives, it can come up far away. Then, many minutes later, if that loon or another one comes up near where the first one went down, the observer might think it was one loon and one dive. OR the loon might keep its body under water with only its beak above the surface, allowing it to breathe while submerged. This is one loon strategy to avoid predators. Sink or Swim: Discussion of Challenge Question #12 "How might a loon's air sacs determine how high or low in the water the loon was swimming?" When a loon fills the air sacs with air, its body becomes much less dense, and more buoyant, allowing it to swim high in the water. As it forces air out of the sacs, its body becomes more and more dense, and it sinks lower and lower into the water. Take the Plunge: Discussion of Challenge Question #13 "If a loon were trying to elude a motorboat, would it be more likely to dive or to sink into the water? How about if it were trying to elude a distant Bald Eagle?" When a loon wants to get away in a hurry, to avoid a mororboat or other fast danger, it dives fast! To avoid a distant Bald Eagle, and to escape detection in the first place while the eagle is still far away, the eagle will slowly sink into the water, without leaving a ripple. Have a Wonderful Summer! This is our final loon migration update for Spring, 1999. We hope you enjoyed learning about this magnificent diver's journey north. See you next year! Copyright 1999 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form