FINAL Hummingbird Migration Update: May 9, 2002 Today's Report Includes: Rubythroats Almost There! Rufous Hummingbirds Reach Yakutat, Alaska! Raising Twins? Hummingbirds Start Nesting Sharing Duties: Link to Lessons More Hummingbird Adaptations: Can You Make a Match? Flowers or Weather: Discussion of Challenge Question #11 Alphabet Dance: Discussion of Challenge Question #12 Year-End Evaluation: Please Share Your Thoughts! Rubythroats Almost There! We add 383 Ruby-throat sightings to the map this week! You'll see that Ruby-throated Hummingbirds are steadily working their way north, but still shy of the cold area around Lake Superior, where snow was on the ground on May 8! And Rufous Hummers are slowly moving inland, away from the mild temperatures of the coast. This spring the weather started warm and some hummers migrated earlier than normal, but with the cold April and May things have defininitely slowed down. With this final report (next time is data only), we'd like to send a big thank you to Lanny Chambers and Mike Patterson for sharing their hummingbird maps and data once again this spring! Ruby-throated Hummingbird Migration Data Migration Map Courtesy of Lanny Chambers, Hummingbirds.net Rufous Hummingbirds Reach Yakutat, Alaska! Rufous Hummingbird, Larry & Terrie Gates 1999 Mike Patterson sent interesting news the past two weeks. Several reports from Idaho and a report from Swan Valley, Montana, came in the week of April 29. Yakutat, Alaska represents the northern-most rufous report to date. Most observers in Alaska report later-than-usual arrivals and blame the unusually cold spring this year. Reports from central and eastern Washington are also increasing as more birds take advantage of warming weather. This week, new rufous hummingbird reports seem to be slowing down as we add only 13 sightings to the map. Cold, unsettled weather throughout the region is probably contributing to the trend. But hummingbird densities west of the Cascades are decreasing. Rufous Hummingbird Migration Data Migration Map Courtesy of Mike Patterson Neawanna Wetland Ecological Observatory Do you wonder why there would be fewer rufous hummers there now than earlier? Probably because the birds migrate along the coastal areas first, and then move inland! Raising Twins? Hummingbirds Start Nesting Photo Dorothy Edgington Even as hummingbirds are still migrating, birds that have arrived at their own breeding grounds are starting to nest. Mike Patterson noted a female Rufous Hummingbird carrying nesting material as early as March 10! And Ruby-throated Hummingbirds start building their nests as soon as they arrive in an area. Female hummers just about always lay two eggs. After a hummer lays her first egg, it takes at least one day, and often up to three days, before she can lay the second. But hummingbird eggs are so tiny (about the size of a large pea) that they need warmth right from the start. So even though there are almost always two babies, the first one hatches 1 - 3 days earlier than the second. Fortunately, hummingbird babies are not aggressive, and the older nestling doesn't hurt the younger one. Are these babies "twins"? Real twins develop when an egg splits in two, or when the mother ovulates two eggs at the same time. If an egg was already fertilized when this happens, both babies will be exactly the same genetically, and we call the twins "identical." If the egg splits before fertilization, the babies will get identical genes from their mother, but different genes from their father. If the mother ovulates two eggs at the same time, the babies will have different genes from the mother and the father both, and will be the same age as each other but be no more identical than non-twin brothers or sisters. Birds only have one ovary, and since its hard for the mother to produce two huge yolks at the same time, females virtually never ovulate two eggs at the same time. Once in a while this happens, or the egg splits, and a double-yolked egg is formed. But if one of these eggs is fertile, the babies are too cramped to develop normally. The inside of an egg is not as stretchy as the inside of a mammal mother! Sharing Duties: How Hummingbird Parents Divide Their Chores Photo Dorothy Edgington Raising baby birds is a lot of work, and requires enormous investments of energy by the mother and father. Some species, like Bald Eagles, share just about all their duties evenly. Some species, like robins, share some chores, while the male and the female take over other chores by themselves. Hummingbird fathers don't seem to be doing ANY work But it turns out that hummer males invest an enormous amount of energy into defending the territory. This is critical for baby hummer survival. If other hummers invade their territory and use up the precious nectar, the mother will have to travel to find more flowers, and the baby hummers will be alone, getting chilled and maybe even starving. So the father hummingbird may not have many "chores," but what he does is still very important. To learn what a pair of hummers must do to raise their babies, see: Hummingbird Nesting Phenology Then try your hand at assigning hummingbird jobs, using this chart: Hummingbird Chore Chart. More Hummingbird Adaptations: Can You Make a Match? This season we've looked closely at hummers from head to toe, learning about some of their amazing adaptations. Could you do some of the things hummingbirds do? See colors that are invisible to other species, including humans Navigate by the stars Fly 600 miles nonstop under your own power Fly straight up, straight down, and backwards, making walking unnecessary A hummingbird easily does all these things and more, thanks to special adaptations. But you'd need a lot of help to do things a hummer does! Try This! Imagine yourself doing some things that hummingbirds do. Play your own "Survival" game to see if you can match the hummingbird adaptation to a human invention to accomplish the same thing. Find our game here: Hummingbird Matching Game Flowers or Weather: Discussion of Challenge Question #11 Last time we asked, "Which do you think is more directly tied to Rufous Hummingbird migration: blooming flowers or weather? Explain your answer." Weather is VERY tied to migration. Hummingbirds simply do not migrate during rain or snow, or against strong winds. On the other hand, Rufous Hummingbirds seem very keyed into flowers blooming. Mike Patterson is studying this question. You can find interesting things about what Mike is learning at his website: Hummingbirds and Flowers. Alphabet Dance: Discussion of Challenge Question #12 Last time we gave you a lesson and asked, "Why are hummingbird flight patterns usually shaped like an O or a U rather than any other letter?" Think about your ABC's. Most of the letters have irregular shapes, straight lines crossing each other, or other things that make it hard for a bird to shape its flight to match. But it's easy for a hummer, who can go up and down and backward, to loop the loop in an O or swoop up and down in a U! Year-End Evaluation: Please Share Your Thoughts! Please take a few minutes to share your suggestions and comments in our Year-End Evaluation Form below. The information you provide at the end of each year is the single most important tool used to guide our planning. Journey North Year End Evaluation Please share your thoughts This is the FINAL Hummingbird Migration Update. Data Only Will Be Posted on May 16, 2002. We look forward to welcoming you back next spring! Copyright 2002 Journey North. 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