Signs of Spring Update: March 13, 2000 Today's Report Includes: Swallows On a Mission Did You Know? Some Birrrrrrds Like It Cooler: Challenge Question #9 Mighty Tiny, Mighty Welcome What Do Swallows Swallow? Mates for Life: Discussion of Challenge Question #4 Swallows On a Mission Every year on March 19, people at the Mission at San Juan Capistrano in California look up in the sky and see their first swallows of the year. It sounds impossible that swallows could time their migration so precisely--and it is! The swallows that have been nesting on the walls of the Mission to rear their young are Cliff Swallows. In San Juan Capistrano they've been a village tradition since at least 1777. Photo: James R. Gallagher Most years, the first Cliff Swallows arrive in California sometime between early February and mid-March. In very rare years they don't get back until late June. But virtually every year at least a few Cliff Swallows return to San Juan Capistrano before March 19. How come so many people see their first one exactly on March 19? It could be that they simply keep their eyes down, trying not to pay attention to swallows, until that day each year. Watching for swallows at Capistrano on March 19 is a long-standing tradition, so TV and newspaper reporters often cover the event. Most reporters, however, aren't birdwatchers. One TV news report about the "Swallows of Capistrano" actually showed White-throated Swifts! Check out this picture of a swallow and YOU won't make that mistake! Did You Know? Photo: James R. Gallagher The Cliff Swallow makes a nest of mud pellets but shapes it like a hollow gourd with a hole for the parents to enter and the babies to look out. The babies and parents recognize each other's voices. What do Cliff Swallows sound like? The family migrates together in mid-October, and parents teach the route to their young. What else is fascinating about swallows? You'll find out when you see: Journey North's Swallow Fact Sheet Some Birrrrrrds Like It Cooler Most swallow species spend the northern winter in South America, and start heading north in February. Days are getting noticeably shorter in Argentina by then, and the birds grow restless. People have counted thousands of swallows passing over Panama as early as February 24. As they continue northward, they join up with Tree Swallows and Violet-green Swallows from the Gulf Coast, and move into the US in early March. The first swallows to continue on to colder areas of the central and northern states and the Canadian provinces are almost always Tree Swallows, which can survive colder temperatures than other swallows. Challenge Question #9: "How can Tree Swallows survive colder weather than other swallows?" (Hint: the answer has partly to do with their sleeping habitat, and partly to do with their guts.) (To respond to this question, please follow the instructions below.) Mighty Tiny, Mighty Welcome Swallows are little birds. The Cliff Swallow weighs less than an ounce (about 24 grams). The Barn Swallow, who can migrate from the bottom of Argentina all the way up to Alaska, weighs even less (about 19 grams). Barn Swallows are found over most of the globe. The only swallow of New Zealand, which looks a lot like a Barn Swallow, is called the Welcome Swallow, but wherever they go, just about every swallow is a welcome one. What Do Swallows Swallow? Swallows eat mainly flying insects, including mosquitoes and other harmful species, so people benefit from swallows being around. And their graceful movements are among the loveliest of any bird. Report the First swallows of spring to arrive in your region to Journey North To catch enough flying insects for survival and good health, swallows spend most of their waking hours on the wing, darting here and there to sweep up small and large insects in their big, wide mouths. When they aren't swooping about, they rest on branches or power lines. A scientist who studied Barn Swallows once calculated that Barn Swallows fly about 600 miles per day just coursing back and forth capturing insects. During migration, swallows are simply flying more in a straight line than back and forth, and so unless they're flying over a large body of water where they can't rest, swallows don't do much more work in migrating than they do in their normal day-to-day living. Because they eat as they go, and because they fly all day anyway, swallows tend to migrate by day (most small songbirds migrate at nighttime). Once in a while a swallow gets lost at sea, but swallows usually follow a land course as they migrate. Mates for Life: Discussion of Challenge Question #4 Last time we asked, "What do bird species that mate for life have in common? Give reasons that would explain why these species might mate for life when others don't." Birds that mate for life include a variety of species, from ravens and eagles to swans and cranes, but they have a few things in common: relatively long life spans, large territories, and, for the most part, only a few young produced every year. If a Tundra Swan or Sandhill Crane arrived on its vast, empty territory in spring without a mate, it might take a while to find one. Both of these species find their mates during the winter, when large groups of their species gather, and the pair migrates together. Every year, the two of them become more familiar with their huge territory--all the little hiding places and good feeding spots, and predators that live there--and every year they become more and more familiar with each other. Year after year they become better at successfully raising babies together. Cranes only lay two eggs a year, and usually only successfully raise one chick each year, so it takes many years together to produce what Red-winged Blackbirds can produce in a single season. Birds with shorter life expectancies would waste time learning all the tiny details about their mate if their mate gets killed before the eggs are even laid. They have to adapt quickly when their mate dies so they won't lose their chance to produce young before their own death. Red-winged Blackbird males put on enormous shows with plumage and song to attract females, and then produce five or six young per nesting. There are so many millions of blackbirds, and the males are so conspicuous, that females have an easy time finding males. And if either male or female dies, it's an easy matter to find a new mate during the breeding season. How to Respond to Today's Challenge Question: Please answer ONLY ONE question in each e-mail message! 1. Address an E-mail message to: jn-challenge-spring@learner.org 2. IMPORTANT: In the Subject Line of your message write: Challenge Question #9 3. In the body of the message, give your answer to the question above. The Next "Signs of Spring" Update Will be Posted on March 27, 2000. Copyright 2000 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form