I’m teaching an Animal Behavior course this semester. The lectures are 80 minutes long and exactly during the sleepiest time of the afternoon; I enjoy the challenge of getting a reaction from the students under these circumstances. Videos of baby animals in peril always get attention (some good ones: marine iguana, barnacle goose, water buffalo), but they’re so reliable it almost feels like cheating.
My students have actually broken into applause during lecture three times so far. One of these will not be discussed in detail (it involved the recitation of poetry), but the other two were in response to two quite different animal accomplishments, which I thought I would share.
This Chestnut-backed Chickadee is molting his head feathers, hence the odd colors.
After breeding, if you’re a bird, comes molting. Time to discard those old, worn, raggedy flight feathers and start with some fresh ones for the long haul of the fall molt, or replace sparse downy feathers with good warm ones for the cold of winter. This means that around now—from mid-July to September—you may see a lot of birds who aren’t looking their best.
The egret chicks at the nesting colony are growing. They’re doing some neat stuff as they grow, like practicing walking very carefully along branches.
But they are also getting up to a lot of nonsense.
Siblings! No fighting, no biting!
The birds are having babies, those babies are learning to fly, and they are flying into our nets at the banding station. They’re not really babies by this point: most of them are independent of their parents. They may have been out of the nest for a month or more, and are technically “juveniles” or “immatures.”
At the banding station we collect data on each bird we catch, including that bird’s age. It’s important to record the age if we can, because the more accurate we are with the age the first time we catch a bird, the more accurate we can be later. If we caught a bird in 2014 and recorded that it was a juvenile, then when we catch it in 2016, we’ll know it’s exactly 2 years old. If we didn’t bother to age it back in 2014, then in 2016 we would only know that it was at least 2. That maybe seems like a small distinction, but the lifespans of wild birds are still an area in which we lack a lot of information, so knowing exact ages is valuable.
How do you tell if a bird is a juvenile or an adult? In some species, the juveniles are dramatically different colors than the adults. Juvenile juncos, brown and streaky, look distinct from adults even from a distance—until they molt, at least. But the differences can be a lot more subtle.
Here is a Common Yellowthroat from the banding station:
How old is it?
Ranitomeya imitator giving his tadpole a piggy-back ride. Photo by John Clare*
You can find poison frogs at zoos, aquaria, and some museums now: tiny and colorful, often hard to see in the vegetation-rich tank until— oh! all those little blue things, that’s them! They’re so pretty! You watch for a while, and they sit on their leaves unmoving, doing accurate impressions of the plastic toy frogs being sold in the gift shop, until you get bored and move on to the next exhibit.
They have a secret: they have rich lives full of interesting behaviors. They just aren’t interested in doing those behaviors in front of you.
Furry animals can spend a lot of time licking their own fur. Here, a mother sea otter demonstrates:
The simple explanation—that these animals lick their fur to keep it clean—is more or less true, but not nearly the whole story: animals get a lot more out of licking their fur than a stain-free coat.
I’ve seen a lot of junco nests in my four years of field work. Rarely, I’ve been lucky enough to happen upon the nest of something other than a junco. I don’t find enough of these other nests to study them, so they don’t help me in my research—but boy, is it fun to find them!
Quick review: this is a junco nest.
This is not a junco nest:
Some major differences: the junco’s is a ground nest, while this one is a cup nest, suspended above the ground in the branches of a bush. The chicks are covered in light greyish fuzz instead of the junco chicks’ dark fuzz, and are maybe a bit stockier than the junco chicks.