Robin Migration Update: March 31, 1998
Today's Report Includes:
Millions of robins were held back by cold weather on the first day of spring, but their migration continued in earnest last week. Imagine how busy you'd be if Journey North observers had spotted them all! Luckily we have "only" 63 sightings for you to add to your migration map today.
This was the first big wave of migratory birds to flood into the northern U.S. states and cross the border into Canada. In addition to robins, many other species were along for the ride: Great-blue herons, wood ducks, red-winged blackbirds, killdeer and others. These maps show weather conditions leading up to March 25th-- on that single day 16 robins were reported and another 15 the next 2 days! Why were this such good time to migrate?
Comments From Northern Observers
A Day in the Life...of a Migrating Robin
What is the typical traveling day of a migrating robin? Let's go along for the ride:
Robins are very unusual migrants in that they can migrate by day or by night! In autumn, many huge robin flights take place in daylight, but in spring, they often fly by night. Why do you think there is a difference between seasons? Might it have something to do with their different food choices in spring and fall?
In spring, robins feel restless, ready to migrate. Their whole body is urging them to establish a territory, mate, and raise babies--but they can't start any of these until they arrive on their breeding grounds.
When cold weather holds them back, robins spend their days searching for food and eating as much as they possibly can. The berries and fruits still sticking to trees after the long winter are the ones that taste the worst--birds eat their favorite berries first of all, just like people eat our favorite Halloween candy first, so the last ones sitting around are
just about always the worst kinds. And for robins, any last berries hanging around are even starting to get a little rancid, so they will only eat them now only if they really can't find anything better. Fortunately, right when they need it most, the ground starts thawing, and suddenly big fat succulent earthworms are ripe for the picking!
Robins eat a lot of food, especially during migration. Their bodies must get as fat as possible to allow them to fly long distances without stopping. This would be unhealthy for us humans, because fat tissue might damage our hearts or block our arteries and veins, but bird bodies are made to store fat very efficiently in a healthy way. When a robin wakes up at first light, he (and the first migrating robins are ALWAYS males) is hungry! He immediately starts searching the ground for any worms or insects he can find. Yummmmm! Cold breakfast!
When his stomach gets full, he starts feeling restless. Migrating robins usually stay in flocks, which is one good way to tell if a robin you're seeing is a migrant headed farther north or one that is going to stay.
You can learn alot by listening to them too: If one of the robins spots a person or other mild danger, if makes its "whinny" call, and the other robins check it out. If the danger gets closer, they take off. If a hawk or shrike approaches from overhead, the first one to spot it opens its beak wide and makes a very high-pitched "Seeee" call, and all the robins instantly crouch low in place and freeze. They can wait for many minutes without moving. Once the danger is past, they all go back to eating. All the robins in the flock are antsy to move on, and suddenly they do--the whole flock just picks up and leaves! In the air or taking off, they often
give their "Zeeeeup!" call, a contact call for migrating.
If the weather is warm and migrating conditions are right, the flock will head in a northerly direction, but if they suddenly spot a promising looking field they'll drop down for a break and a snack. If the weather is too cold for migrating, they'll search for likely fields where they can find food in more
of a circle, all around the area they're in. Sometimes, if the weather turns very cold, they'll actually head south again in their search for food.
All day long they eat and move about restlessly. When night comes, they sleep. Until, one night, when they have lots of food in their stomachs, lots of fat on their bodies, and the weather has been just warm enough, suddenly they REALLY take off!
Robin daytime movements are pretty low to the ground. But at night, when they have trouble seeing shadows, they rise higher to avoid bonking into things. They may fly as high as a mile up in the air, though usually they fly lower than that.
When each robin finally arrives on his territory, he bursts into song! It sounds as if he's singing from sheer joy to be home, but as humans, we really can't be sure how birds really feel. We do know that his song tells other robins to STAY OUT! And when migrating robins hear a territorial
robin's song, it makes them more restless to press north to find their own territories.
Has YOUR Robin Returned Yet?
When WE hear a robin's song, we know that this is our very own robin--the one who will stay here for the summer. What a welcome sound that is!
The first day you hear this song, you know your robin has arrived and is ready to spend another summer with you.
Challenge Question #10: Where Was the Robin Yesterday?
Robins migrate at a speed of about 50 kilometers per hour. On the first day of spring, when night is exactly as long as day everywhere on the planet, how far might a robin go on its night flight? Look on a map and see if you can guess what town or city your first robin of spring might have left the night before.
How to Respond to Today's Challenge
1. Address an e-mail message to: firstname.lastname@example.org
The Next Robin Migration Update Will be Posted on April 7, 1998.
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