Oriole Migration Update: April 5, 2001 Today's Report Includes: Where are the Orioles? This Week's Migration Map and Data Dr. Aborn's Weather Forecast for the Birds Celestial Navigation: Challenge Question #3 Finding Their Way in the Dark Teacher Tip: Follow the Stars A River of Birds Beep! Beep! Try This Teacher Tip: The Built-in Barometer Orioles Round the Bases Keep Kitty Indoors! Poster Contest: National Keep Your Cat Indoors Day Two Different Birds? Discussion of Challenge Question #2 Where are the Orioles? As you can see from the map and data, there have been a few sightings of migrating Bullock's Orioles in the western states, though none have reached Oregon quite yet. Bullock's Orioles move along the coast at first, and if they hit a sudden spring storm, can stop right where they are. Many Baltimore Orioles cross the Gulf of Mexico, and can hardly stop in the middle of that huge body of water if they hit a storm! So they wait until later than Bullock's to begin their migration. Bullock's Oriole Migration Data Today's Migration Map Oriole Range Map by Macalester College Where are the orioles coming from? This range map above shows breeding range for both species, and their common winter range. Several Baltimore Orioles wintered in the eastern half of the continent this year, but we took them off our map for now sowe won't get confused when actual migration kicks in. If winters grow milder in the future, these non-migrating orioles may become more common. They pass their non-migratory genes to their offspring, and if weather and winter food allow more and more of them to survive, they may multiply at a greater rate than the truly migratory individuals. When is it time to start looking? From Texas, Journey North observer Harlen Aschen sent us this great "rule" for timing the arrival of orioles: "Start looking March 15th but don't expect much until the tax has been sent in (April 15th)." Harlen also notes that in Texas when mulberry fruit is ripe, "there will be orioles and tanagers." When you see your first oriole this year, pay attention to what plants are doing, to see if your area also has a special plant event happening at the same time. Dr. Aborn's Weather Forecast for the Birds Dr. David Aborn Dear Students: "In my last report I mentioned a cold front that was moving across the country. I said that the rain and north winds that came with it would force migrants to land, and that is what happened. After a few days, as the high pressure area moved east, the winds started coming from the south, allowing the birds to move northward. "The coming weeks promise even more excitement! This week, a cold front has stalled across the Gulf coast states. This means that there have been several straight days of bad weather. Any birds arriving from the tropics will be grounded for a while, and people in those states should have some great birding. On April 1st, the Texas coast reported 23 species of warblers! The front is expected to weaken and fall apart this weekend, which should allow all those birds to continue their journey north. People in the Midwest and mid-Atlantic states should be ready to see some good birds! There do not appear to be any new fronts coming in until the middle of next week, so there may not be anything to force birds to land in large numbers. Things are really starting to pick up, however, so keep your binoculars handy! Happy Birding!" David Aborn Find the weather map and read more about the species of migrating birds spotted with the rest of David's letter here: Weather Forecast for the Birds Celestial Navigation Photo courtesy Provincial Museum of Alberta Every spring, orioles and other migrants flood over the Gulf of Mexico to their breeding grounds in North America. Some birds migrate over land the entire way from central and northern South America, but in spring they often head out right over the Gulf of Mexico. Most of these birds set out right as night is falling. See Last Night's Migrants That leads to the question: Challenge Question #3: "What advantages does night migration have over day migration? What special dangers does night migration have?" (To respond to this question, please follow the instructions below.) Finding their way in the Dark Here's another question: How do night migrants find their way? They have a few different systems, but most rely heavily on stars to find their way. Ornithologists have discovered that many baby birds look up at the sky during the time they're in the nest. They learn the patterns of stars, how stars seem to rotate in a circle as the earth rotates, and which star in the Northern Hemisphere never changes position. Even when clouds obscure most of the sky, birds can set their direction if they can see a wedge of stars. In autumn they migrate away from the North Star and in spring move toward it. Teacher Tip: Follow the Stars Imagine! A young bird lies awake at night in its nest looking at the sky and observing something few people realize: The night sky rotates in a complete circle every 24 hours. All the stars appear to move around the sky in a big circle except one--the North Star. Why? Explorers have used the North Star for navigational purposes for centuries. It might be a surprise to know that animals can use stars as a compass too. In this activity, students learn how they might use the North Star as a compass. We provide reproducible patterns and instructions for students to make their own Sky Map Star Clocks. These devices will help them visualize the full rotation of the stars. They can even tell time with their Sky Map Star Clocks. Go to: Finding Their Way--The Stars as a Compass A River of Birds Each spring, roughly a billion birds migrate northward across the Gulf of Mexico, en route to breeding habitats from their wintering quarters in the tropics. Imagine being a bird, flying over hundreds of miles of water without food or any place to rest. And imagine being there to watch as thousands and thousands of migrating birds fly over your head! People working on oil platforms on the Gulf of Mexico don't have to imagine it. They've had the experience. Read one observer's description: A River of Birds Beep! Beep! If hundreds of orioles, along with thousands or millions of other birds, migrate over the Gulf on a single dark night, how do they keep from bumping into each other? Unlike cars, birds don't have headlights, but they can do something similar to what car drivers do to help other drivers notice them. In the way that car drivers use horns, birds make little calls as they move. Fortunately, birds have such good hearing that they don't need to be as loud as car horns! But the tiny sounds that migrants make can be heard hundreds of feet away on the ground. Try This: When migration starts in your area, choose a nice night, when birds might be migrating, and stand out in your backyard after dark. Listen! Do you hear any migrating birds? Teacher Tip: The Built-in Barometer Like all travelers, birds pay close attention to the weather. Scientists also have known for a long time that migrating birds fly at different altitudes than non-migrating birds, and maintain this altitude even on moon-less nights when they can't see the ground at all. Many scientists suspect that their ability to "feel" air pressure helps them maintain a particular altitude. Studies have proven that birds are extremely sensitive to small changes in air pressure, comparable to differences of only 5 to 10 meters in altitude. A very sensitive inborn barometer is a handy adaptation for all birds, even non-migrants. But recognizing air pressure helps migrants because birds often migrate along frontal systems, and changing air pressure is one of the first signs that a front is coming. High pressure systems often have clear skies, which make using celestial navigation easier, and flying on high pressure days may even help "buoy" birds up a bit. Interested? Investigate more with our lesson: The Built-in Barometer Orioles Round the Bases It's April and time for baseball season openers. Have you noticed that the Baltimore Orioles baseball team recently made their logo look more like the real bird? Did you know that they hand out baseball cards with orioles on them at their ballpark? They show orioles on their scoreboard too. The team also promotes International Migratory Bird Day. Go Orioles! Keep Kitty Indoors! Poster Contest: National Keep Your Cat Indoors Day The American Bird Conservancy's first national poster competition was held last year with entries from 28 states. Did you enter? This yearís contest will yield winners in three age categories: Ages 6-7, 8-9, and 10-12. The deadline for competition entries is May 1, 2001, so you have plenty of time to create your entries. Your poster should depict a happy, safe, indoor cat. Winners will be announced by May 12 on American Bird Conservancy's Web site. Find out about prizes, poster sizes, and where to mail your entries at this site: American Bird Conservancy View Last Year's Poster Competition Winners During migration, birds are particularly vulnerable to predators. They are unfamiliar with their surroundings, and tired and hungry after the long journey. This makes them perfect prey for a cunning cat roaming outdoors. Cats are dangerous predators for birds at other times of the year, too. For example, most young birds leave the nest before they can fly well. Any newly fledged baby birds on the ground or taking short practice flights are easy prey for a cat. There's an easy solution: Keep kitty indoors. True or False? Worldwide, cats may have been involved in the extinction of more bird species than any other cause, except habitat destruction. To see the answer, and why keeping kitty indoors isn't just for the birds, go to: Keep Kitty Indoors Two Different Birds? Discussion of Challenge Question #2 Last time we told you that recent DNA work has supported an AOU decision to "split" the Northern Oriole into two separate species: Baltimore and Bullock's Orioles. We asked, "What differences can you name between Baltimore orioles and Bullock's orioles?" Baltimore Oriole Bullocks Oriole Appearance: Males of both species are orange, black and white, but the color pattern is different. Female Bullocks are grayer and whiter than the more brown and orange-yellow Baltimores. Sound: Their songs are somewhat different. Range: The Baltimore Oriole is found mostly in the eastern part of the continent and the Bullockís in the western. Molt: Baltimore Orioles molt their feathers after breeding while still in the north. Bullockís Orioles molt on their wintering ground. DNA: Baltimore and Bullockís Oriole DNA suggest that the two species are actually much more different than ornithologists used to think! Journey North talked to the ornithologist who researched the decision to "split" the Northern Oriole into two separate species. We asked him how the committee came up with their decision, and why the two orioles were ever considered the same species in the first place. His answer is here: From Northern Oriole to Baltimore and Bullock's: A Split Decision How to Respond to Today's Challenge Questions: IMPORTANT: Answer only ONE question in each e-mail message. 1. Address an e-mail message to: jn-challenge-oriole@learner.org 2. In the Subject Line of your message write: Challenge Question #3 3. In the body of your message, give your answer to the question above. The Next Oriole Migration Update Will Be Posted on April 19, 2001 Copyright 2001 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form