About Ask the Expert Answers From the Loon Expert Photo: Dr. F.G. Irwin Ted Gostomski LoonWatch Coordinator Sigurd Olson Environmental Institute Northland College, Ashland, Wisconsin. Special thanks to Ted Gostomski, for providing his time and expertise in responding to your questions. Questions From: Lac La Biche, AB ksanders@sandnarrows.com Q. What is the reason for loon 'rafting' in the fall before their southern migration? (rafting being when they gather in huge numbers) A. We are not real sure, but we think that rafting helps loons to feed more efficiently. If they are feeding in groups then they are not spending their time chasing off other loons who are intruding on their feeding area. Sharing a space makes more sense because then everyone can spend their time eating. It may also help to prevent loons being attacked by predators because there are more eyes looking out for attacks. Adult loons don't have very many predators, though, so this is probably not the reason. Q. Do all loons 'raft' with others for migration? A. We know that Yellow-billed Loons do form rafting groups during migration. There is not a lot of information on similar behavior for the other three species of loons (Arctic, Pacific, and Red-throated), but it is likely that they form rafts as well. Q. Is there any importance to the lakes that loons raft up on? Will anylake do or are they specific in their needs? A. Lakes where loons form rafts are probably not being utilized as a nesting territory by a pair of loons, or if it was a nesting territory, the nesting is done and the pair are no longer defending it. The primary importance for a "rafting lake" is that it has to have a lot of fish to feed on. Having islands and deep water seem to be some other important characteristics, as loons tend to raft over the drop offs in a lake, and the islands provide important protection from wind. Questions From: ON Scott Young Public School, ON kevin.adams-syps@fc.vcbe.edu.on.ca Q. Why do loons only have two eggs? A. This is kind of a difficult question because it has two answers that are both related to the evolution of loons as a species. The first answer is that loons only lay two eggs because their body size and physiology (how their body works) does not allow them to produce any more than that. Loon eggs are about the size of one and a half tennis balls. That's a big egg, and it takes a lot of energy to produce two of them! In order to gain that energy loons have to eat a lot of fish and NOT spend time chasing off intruders or other activities that use up their energy. The other answer is that loons live for a long time. It is believed that loons can live to be 30 years old, which is a long life compared to most birds. Animals that have long life spans produce low numbers of young because it prevents overpopulation and exceeding the carrying capacity of the habitat. Q. Why are the eggs laid and hatched on different days? A. As I mentioned above, making a loon egg takes a lot of energy. To produce two of them at once would take even more. Besides that, loons would need to be bigger birds to hold two eggs inside them that are as big as one and a half tennis balls. So loons work on one egg at a time. Usually a loon lays its eggs one day apart. Because they are laid one day apart, they also hatch one day apart. Q. What are their favorite fish in their winter (Florida) and summer (Canada) grounds? A. Because loons typically eat what they catch while still underwater, we do not have a good idea of what they really like to eat, but based on observations of food brought to the surface, we know that during the winter loons eat, among other things, flounder, crabs, lobster, shrimp, gulf menhaden, bay anchovies, and silversides. During the summer, the loon's favorite food is yellow perch, but they will eat whatever is available and what they can catch. This includes trout (though trout tend to be too fast for loons) and aquatic insects like dragonfly larvae. Questions From: Beaufort, SC rvdien@islc.net Q. Since Loons summer in the north on fresh water, and winter on the coasts of the south in brackish and salt water, how are they equipped to expel the salt from their system taken in from eating salt water fish and drinking salt water? A. Loons have a pair of salt glands above their eyes which expel salt taken in from seawater. These drip almost constantly during the winter season. Q. I have observed that loons are silent in the winter here in the south, Why is this? A. Though loons have been heard giving yodels and tremolos on the wintering grounds, it is not common. It probably is because the hormone levels in loons are not high enough (i.e., they don't feel a need to defend a territory) to bring about calling. Besides that, loons spend more time in groups during the winter, so the long distance calls like yodels and wails are not needed. They can communicate with quiet hoots to one another. Ted Gostomski LoonWatch Coordinator Sigurd Olson Environmental Institute Northland College, Ashland, Wisconsin. Visit the LoonWatch Web site Copyright 1999 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form