American Robin Migration Update: May 1, 2001 Today's Report Includes: This Week's Migration Maps and Data At the Top Not Exactly Summer Go Lay An Egg: Challenge Question #22 Welcome to the World! One Robin, Two Nests? Challenge Question #23 Spying Worms Listening or Looking? Discussion of Challenge Question #18 Breakfast, Lunch, Dinner: Discussion of Challenge Question #19 Tug of War! Discussion of Challenge Question #21 Year-End Evaluation: Please Share Your Thoughts! This Week's Migration Maps and Data (For data, click on caption.) First Robins Seen Waves of Robins First Robins Heard Singing At the Top Robins have reached all but 5 of the Northern Observation Posts! By April 25, there were several robins singing in Kenai, AK, according to Brian Bailey. Here's what our northern observers are seeing: Pam Randles of Haines, AK, noted on April 24, "Yesterday as I was driving around the area, I saw waves of robins. It is difficult here to see the waves because we live in pretty dense forest, and we are a small town with few lawns. But there were definite groups of 8 or more robins, and they are singing everywhere." On April 26, 2001, Sara Hepner from Sterling, AK, saw "one beautiful male robin picking through dead leaves along the road this morning. He wasn't making noise yet, but he was here, and was very pretty. This is usually the week they show, so he's right on schedule." Fred Broerman writes on April 25, 2001, from Bethel, AK, "We had our first Robin sighting yesterday and one has been singing outside my window all today." Mike Sterling of Anchorage, AK, wrote on April 27, "Yeah, there are TONS of birds coming through here now. I pass a coastal wildlife refuge--a big waypoint on many migrations-- going to school on my bike every morning, and the sound of geese, ducks, swans, cranes, and songbirds is getting overwhelming. The big robin in my yard is finding answers to his territorial chortles, and the bugs are out. The big wave hasn't quite arrived here, though I am hearing more every morning." K.C. Robertson reports robins April 20 in Clarenville, NF. On the same day (April 20) in Nipawin, SK, Vi and Richard Darling report, "Ta-dah!! This afternoon a pair of robins flew into our glassed-in car port. I had to help one of them find their way out the door, but hope they will make a nest with us." Robins reached Homer, AK, on April 19. Stan White reports, "First Robin sighted singing atop a spruce tree. Same place as last year; possibly same bird? (He sounds the same.)" On April 19, 2001, another observer reported a robin in Pullman, WA, and was surprised to see one at such high altitude so early. Jill Rogers of Sacred Heart School in Corner Brook, NF, reports that robins "finally arrived!" on April 18. Margot Hervieux of Grande Prairie, AB, writes, "Finally, yes! I heard three different robins on April 27th." Kristina Owens of Fireweed Academy in Homer, AK, wrote on April 27, "Yes, we have heard Robins singing! No sightings right around the school though." Not Exactly Summer Courtesy Ann Cook. Robins and humans alike are waiting for warmer weather at some northern observation posts. "Everyone agrees that it feels like spring at the lower elevations but it is still very snowy up high," wrote Kristina Owens of Fireweed Academy in Homer, AK on April 27. "Photoperiod is approaching sixteen hours with daytime temperatures in the high 40's and low 50's. Nights are in the 30's." Marc Landry wrote cool notes from Beresford, NB, on April 29: "Water is frozen in the morning and the activity in the soil is not acting up. Poor robins... no worms yet." Marc noted on April 27 that robins were starting to pair up and were much more territorial. We'll keep you posted on the news from five Northern Observation Posts that have yet to report seeing their first robins: Fairbanks and Valdez, Alaska and Pinawa, MB; Lion, ON; and Beresford, NB. Still, it won't be long now until robins across the continent are sitting tight, incubating the next generation. Go Lay an Egg! While we're waiting for robins to reach the end of the migration trail, the breeding cycle is underway in places where robins have already arrived. The main purpose of a robin's life is to make more robins. Migration, territory, courtship, nest building, egg laying, incubation, and care of the young--all are parts of the breeding cycle. These activities happen so robins can pass their genes on to new generations. But who do you think does more work in raising young, the robin male or the female? Which robin takes more risks, the male or the female? Which robin would you rather be: a male or female? How does a robin produce an egg? Why does she lay only one egg per day? Why is four the best size for robin clutches? You'll be able to answer these questions a lot better after digging into the pages we've made to help you collect clues and sort facts: Eggstra! Eggstra! Read All About It! Chore Chart for Raising Robins When you know the story behind the eggs, come back and answer: Challenge Question #22: "If a robin lays her first egg on May 1 and everything happens in an exactly average way, what date do you think her babies will fledge from the nest?" (To respond to this question, please follow the instructions below.) Welcome to the World! How old do you think these robins are? Why are only two hatched? When will the other(s) hatch? Photo Courtesy of Jim Gilbert Baby robins grow quickly--from the size of their egg to the size of their parents in only about two weeks! Check out the questions in this photo caption! Hatching out of an egg can take an entire day. Each chick must fight its way out of the egg. First it breaks a hole in the shell with its egg tooth, a hard hook on its beak. Then the baby pokes and stretches and struggles, with rest stops in between, until it breaks free of the shell. Eggs usually hatch a day apart in the order they were laid. One Robin, Two Nests? Photo courtesy of Jim Gilbert. Journey North received a question that helped us all learn something new! It came from Dawn Chance of Rochester, MN, who writes, "We have a pair of robins nesting under our deck on the supporting beam. We have been watching the female fly off to collect nesting material. She has built 2 nests within 5 feet of each other. Is this common? I thought at first she had started one and abandoned it, but she has worked on them both and they are almost finished, and in 2 days! Can you tell me any reason why she would do this? Could she be building her second nest already for summer?" Journey North's robin expert Laura Erickson has never observed double nesting in robins, so she wrote to Len Eiserer, author of The American ROBIN: A BACKYARD INSTITUTION. Len writes back, "Building multiple nests simultaneously happens every now and again in robins. One started 26 different nests on roof rafters of a garage under construction; another built 8 on successive steps of a fire escape. "Support from underneath is the primary site selection factor for the female robin--it's more important than concealment, e.g. Since some human structures provide repetitive sites with terrific support, the female can get 'seduced' into building multiple nests. This is an example of "supernormal stimuli"--artificial stimuli that are even more effective than those provided by Mother Nature (tree limbs in this case). Animals have a hard time resisting supernormal stimuli." Challenge Question #23: "There are some records of robins building more than one nest, but very few. Most people, including people who study robins, have never seen this happen. Why do you think this is such a rare event?" (To respond to this question, please follow the instructions below.) Spying Worms Last time we talked about worms, a favorite robin food. Many people wonder how robins find the worms. Most scientists now conclude that robins find worms by vision, thanks to experiments by an ornithologist named Frank Heppner. In his experiments, Heppner investigated all the robin's senses. Heppner established that vibrations, odors, and sounds do NOT help robins find worms. Instead, robins SEE worms inside their burrows or wiggling on the ground. Robins cock their heads to improve their ability to look at the ground. Some robins find worms the EASY way; they learn that worms emerge from burrows after rain, which can make them really easy to pick up on sidewalks. So, that's the answer to how robins find worms, but figuring it out wasn't easy. Last time we asked you the following question about Heppner's experiments to learn how robins find worms: Listening or Looking? Discussion of Challenge Question #18 Photo courtesy of Jim Gilbert. "If you had the materials Frank Heppner used, how would you design experiments to prove which sense(s) robins use to find worms? Why do you think he used each of these materials?" Pieces of dead earthworm Living earthworms Rotten eggs Decaying meat Rancid butter Mercaptoacetic acid (which smells like a cross between sewer gas, rotten cabbage, a skunk, and a stinkbug) A small drill A tape recorder that was extremely sensitive at low frequencies Several students from Ms. Sheer's fourth grade class at Glenwood School in Chapel Hill, North Carolina, pondered this question long and hard and came up with some fabulous experimental designs. Some were exactly what Dr. Heppner had thought of, and some would make fascinating experiments on their own. We'll categorize their suggestions with the five senses: HEARING The class writes: "The tape recorder can pick up very faint noises so the person starts the drill at low speed. The tape recorder catches the noises and puts the noise near the robin. It might hear the little noises and go down and look at the tape recorder, thinking it is a worm." That's exactly what Dr. Heppner did . Using VERY sensitive recording equipment, Dr. Heppner taped the low-frequency sounds made by burrowing earthworms. He found that robins ignored the sounds. SMELL Ms. Sheer's class suggests: "Mercaptoacetic acid smells really really bad, so the worms are attracted to the smell and robins will smell the scent and go down to where he smelled the smell and dig." Alternatively, "The scientist might put a living earthworm close to a robin, and if it comes down to get it, you will know that the robin is either using its sense of smell or its vision. The scientist might take another earthworm, cover it with one of the smelly substances and then put it at the same distance from the bird. If it comes down, it was probably using its vision. If it doesn't, it was using its sense of smell." We don't know if worms are attracted to mercaptoacetic acid, but Dr. Heppner recorded that "robins nonchalantly ate foods smelling like rotten eggs, decaying meats, rancid butter, and the absolutely worst smell of all bad smells, mercaptoacetic acid." He concluded that robins don't seem to notice that nice wormy smell at all! TASTE Robins would have to taste a LOT of dirt to pick out worms this way! So neither Dr. Heppner nor Ms. Sheer's class even considered this possibility. TOUCH If robins feel vibrations of live, wiggly worms, they wouldn't bother eating still, dead worms. But when Dr. Heppner drilled worm-like holes in the ground and placed dead worms in them, the robins peeked in the holes, found and ate them readily! Do you think robins would eat dead worms just laying around on top of the grass? That would be an easy experiment to try! Ms. Sheer's class suggests using "dead earthworms and live earthworms to see what robins will go to. If they go to the live ones, they are probably using their sense of vision because bits of dead earthworms don't look like live ones." Which brings us to: VISION Dr. Heppner concluded that robins look for earthworm holes that have a worm within visual range. When Dr. Heppner drilled holes that looked exactly like wormholes, robins ignored the holes UNLESS a worm was in them. Whether that worm was alive and normal, alive but coated with a bad-smelling odor, or dead, the robins found and ate it. Breakfast, Lunch, Dinner: Challenge Question #19 "What might be the reason for a robin's feeding pattern of hunting for worms in early morning and late afternoon, and eating fruits, spiders and other small creatures at mid-day?" Tamar in Ms. Sheer's fourth grade class at Glenwood School in Chapel Hill, NC. has the answer: "Worms like wet ground, so in the morning when the ground is wet the robins will probably find more worms, and find the other things at mid-day." Good thinking, Tamar! Laura, our robin expert, adds some details: "Worms are most active at night, when robins can't see them, and during the cool, moist morning and evening. After the sun has dried up the dew on grass and the humidity of a lawn goes down, worms retreat deep into their cool, moist burrows for the heat of the day. That's when robins resort to other food sources until the worms come back up." Tug of War: Discussion of Challenge Question #21 Last time we asked: "Why must a robin tug so hard to get a worm out of the ground?" A worm's anatomy is the clue to the answer: A worm's body has hair-like bristles called setae that help the worm crawl and also to grip and anchor itself firmly in the ground. Worms can grip and anchor so firmly that robins must tug to get them out of the soil. 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 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-robin@learner.org 2. In the Subject Line of your message write: Challenge Question #22 (or #23). 3. In the body of each message, answer ONE of the questions above. Please Report the First Robin you SEE, the first robin you HEAR singing, and other interesting robin observations. Your reports will be incorporated into these Robin Migration Updates. The Next Robin Migration Update Will be Posted on May 15, 2001. Copyright 2001 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form