Robin Nest Cam Lesson #2: New Babies!
As you watch the video clips, notice these things:
After viewing the videos, discuss these questions with your classmates or in your journal! (Discussion of these questions will appear in Robin Nest Cam Lesson #3.)
Discussion of Questions from Lesson #1
Why does the mother wiggle back and forth as she starts incubating?
You may have guessed that the wiggling, or the friction from it, is what keeps the eggs warm. But what actually warms the eggs is the mother's bare tummy. When you look at a robin, its whole body appears feathered, but actually adult females lose all the soft down feathers that cover their belly before laying eggs. Larger outer feathers from the sides and breast cover this bare spot, called an incubating or brood patch. When the mother sits down to incubate, she uses some of her skin muscles to pull the feathers off the brood patch so her hot skin will be in direct contact with the eggs. Second and third grade students in Crested Butte, Colorado, made some very careful observations. One thought "she might be trying to move around until she covers all her eggs evenly." Another added that she might wiggle "to make sure her feathers covered the outside edges of the eggs." This would help ensure that the mother's heat doesn't leak out the sides of the nest. One student thought she might be rubbing on the eggs
to warm them like we rub our hands together when our hands get cold. This makes sense. Imagine someone putting a cold hand on the back of your neck. A mother robin's tummy probably gets that same sharp feeling when it touches cool eggs. One boy had seen an egg incubator and noticed it heated and rolled the eggs. He thought she might wiggle to turn the eggs before she warms them. Actually, she MUST turn the eggs every day, but normally does this with her beak. Journey North's Robin Expert Laura thinks the tummy wiggling does all these things, and is most important both to help the mother make sure she's in contact with all of the eggs and to make sure she's comfortable--she's going to be sitting for many long minutes!
Why don't the eggs break under her?
Some middle school students suggested that "A robin's eggs won't break under her weight because she doesn't put all her weight on them. She puts just enough weight to keep them warm till they hatch." Some first grade students added, "The eggs are strong. The shell is hard so when the mother sits on them, they won't break. The shape is an oval and that shape is strong." And that pretty much covers it!
Why is the mother's mouth open in the second video clip?
Some students suggested she could be squawking at a predator close to the nest, but if you look closely, you can see that even though she moves her head a little, looking about, her throat isn't wiggling at all. Also, when she shifts position, she still keeps her mouth open. What the mother is doing is panting! Her body must warm the eggs, but sitting in the sun as she's doing she gets a little overheated. Her tongue doesn't loll out the way a dog's does, but the open mouth helps her to keep cool.
Why doesn't she take a nap since she's stuck in one position anyway?
Some second graders were as observant as a mother robin! They wrote, "She is guarding the eggs so no one will get them. We saw a shadow flying near the dome in the third clip. She is watching to keep the eggs safe." If the mother spots a snake, cat, hawk, or sometimes even a nearby person, she'll squawk, and then she and her mate, and maybe some other birds, will form a mob that will fly at and harass the predator until it goes away.
What do you think made the mother robin choose this nesting spot, on a ladder inside a partly-finished geodesic dome, for her nest site?
Some seventh grade students suggested that "The mother robin probably picked this nesting spot because no one can really see her in a high place. Also, she is probably nesting there in a geodesic dome because it was almost finished and it is hard for predators to find them." And first graders added, "The dome would be good protection from the rain and other bad weather, like snow and hail. A greenhouse would be a warm place to keep your nest. She went to the ladder because if she was at the top, other animals would have a harder time getting to her nest. It might be quieter there as well."