FINAL American Robin Migration Update: May 16, 2000
Today's Report Includes:
Reaching the End of the Road
Spring's robin migration is reaching the end of the road! From Alaska's chilly Tuluksak Junior High School (61.11N, -160.95) comes this news:
The robins have reached Alaska's Denali National Park, too, according to Mitch Knabbe of Tri-Valley School in Healy, Alaska (63.9N, -148W). Mitch says,
Although the newest arrivals in Alaska weren't reported singing yet, it won't be long now until robins across the continent are sitting very still, incubating the next generation. Speaking of this season's baby robins. . .
Welcome to the World!
Baby robins grow quickly--growing from the size of their egg to the size of their parents in only about two weeks! For their first four days of a nestling's life, the parent birds regurgitate partly digested food into the orange, yawning mouths of the babies. By their fifth day, the nestlings are receiving earthworms that have been broken into small mouthfuls. As the days go by, parents give the babies complete worms and large insects. Fred Charles found that Illinois robins put in 15.5 hours a day feeding young in late May, bringing an average of 356 pieces of food daily! In his book "The American Robin," Roland Wauer says this food is composed of:
Try This! Make a pie chart showing what baby robins
Splish, Splash, Robin's in the Bath
What's the best way to attract robins? Provide water! Few birds bathe as often as American Robins. If you watch them, you'll see how much they enjoy baths! Sometimes several robins line up around a birdbath and wait contentedly for a turn! Whether the water is in a birdbath or pond, robins will drink and bathe whenever water is available. If you have a birdbath, water only an inch deep is enough to attract robins. Moving or dripping water also attracts more birds than a quiet birdbath.
Watch as they dip and splash water in every direction, and see what tremendous splashes they can make! Bird expert Roland Wauer believes that robins will bathe twice a day and will look for any water to bathe in. They'll go for tiny mud puddles, puddles left from watering the lawn, snow water along roadsides, stock watering tanks on farms, and even rain baths.
Robins sometimes take dust baths, too, although these are less common than water baths. Birds in dry areas are likely to take dust baths as a way to maintain their feathers. Frequent dusting helps to keep just the right amount of oil on the feathers. Any extra feather oils are absorbed by the dust and fluffed off along with dry skin. Dusting may also discourage bird lice.
You might even see a robin take a sunbath on the lawn, crouched on the grass with wings spread, or lying on one side with an uplifted wing so the sun can penetrate the fluffed-out feathers.
You already know that robins love worms! Last time you learned that worms have lots of nutritious protein and and valuable calories for robins. But robins round out their diets with food besides worms. When robins are running on a lawn hunting for worms, they're also searching for other tasty morsels. They eat beetles, caterpillars, spiders, and even snails and slugs. All are rich in protein and other nutrients that robins need for growing strong bodies and new feathers.
Use binoculars to carefully study a robin on a lawn. Can you identify any of its prey besides earthworms? Make a list of the different animals a robin takes.
Spread the Word: Poster Contest
Did you remember National Keep Your Cat Indoors Day on May 13? If you sent a poster entry for the contest we told you about in our March 21 Update, check out the American Bird Conservancyís Web site where the winning poster will be featured:
Most important, remember the message and pass it on: The lives of
billions of songbirds will be saved each year (and pet cats will be safer too) if people keep cats indoors. The
birds and cats will thank you, and so will future generations who will still see and hear the songbirds that beautify
each spring and summer.
Answers From the Robin Expert
Special thanks to Laura Erickson for providing her time and expertise in responding to your questions! Don't miss this year's questions and answers:
Robin Attitudes at Different Latitudes: Response to CQ #19
Last time we asked: "If we estimate a 2-week delay for every 5 degrees north in latitude, and we assume robins in Jackson, Mississippi are now beginning to lay eggs, when would you expect robins in Madison, Wisconsin to begin laying their eggs?"
Jackson is at 32.32 N, and Madison is at 43.08 N, so that's a difference of about 11 degrees. If there's two weeks' delay for every 5 degrees north, robins will probably lay eggs in Madison about 4 weeks later than robins in Jackson.
Robin as Predator: Response to Challenge Question #20
"Calculate how many calories per gram of body weight a 100-pound child needs, and how many calories per gram an adult robin needs. Which needs more? Why?"
Calories provide the energy that fuels every living thing. A normal, active child who weighs 45,000 grams requires 0.049 calories per gram every day. Just to keep breathing, a robin weighing 55 grams requires 0.34 calories per gram every day, almost ten times as much as a child! This is because robins have such a high rate of metabolism. Their hearts beat much faster, they breathe faster, and they keep their body temperature at about 106 or 107 degrees.
Response to Challenge Question #21
We asked: "If a robin requires a minimum of 18.9 calories a day just to keep breathing, and an average worm has 0.7 calories, how many worms does a robin need to eat each day just to stay barely alive? Why do robins seem to prefer nightcrawlers over smaller worms?"
Hooray for Kelcie and Barbara from PA, who had the answer! They said, "The Robin would need to eat 27 worms to stay alive. The Robin would prefer nightcrawlers over worms because they are bigger and they would have more protein and therefore more calories."
Bird expert Laura Erickson added, "They probably need more like 50 a day to stay healthy and active, especially while growing new feathers! They prefer nightcrawlers and other large worms because these worms have the biggest bodies and the most calories. Robins can get more food for less work."
Robin as Prey: Response to Challenge Question #22
We asked, "Why are robins so much warier in forests?" If their timid behavior in forests seems strange, you'll understand when you think about this:
Robins in backyards get used to people, but robins in forests do not. Also, our backyard robins usually have a clear view of a much wider distance than robins in forests, so they can more easily figure out what people and other potential enemies are doing than robins in forests can. If people or other "intruders" don't pose a real threat, the backyard robin doesn't need to fly away. The forest robin flies away because it's better to be safe than sorry!
Year-End Evaluation: Please Share Your Thoughts
This is the FINAL Robin Migration Update for Journey North 2000.
We have had a lot of fun learning about YOUR robins this spring! Thanks to everyone who shared observations to build a picture of the robIn's spring migration. And three cheers for everyone who will watch their robins with a caring and attentive eye this summer!
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