You would think an embryo in an egg could relax. They can’t eat, or go anywhere; what can the world ask of them, besides that they grow? A decade ago it would have seemed ridiculous to talk about “embryo behavior.” Now, though, we know that even embryos have things to do.
There’s more going on in there than you think. Photo by Chris Setter on flickr, used via a Creative Commons license.
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.
This is the strangest nest placement I have seen from my juncos so far. The setting is a meadow with scattered corn lilies, an area favored by the cattle that sometimes graze in my field sites. The holes you see in the dirt are footprints left by cow hooves in the soft ground.
Nesting moms, are you having trouble fitting all your babies into one nest? Your troubles are over! We’ve got photos to inspire you to fit all those babies into one nest in an elegant, orderly way. A successful breeding season doesn’t have to mean clutter anymore!
These eggs are a mess. Look at that one shoved under the others. Don’t let this be your nest!
One of birds’ most endearing qualities has to be their care of their chicks. Sparrows fly in and out of nests in the rafters of gas stations, doggedly exhausting themselves to feed their hungry offspring; ducks and geese lead lines of fuzzy yellow babies across roads and around ponds; and we humans see ourselves in this tender parental care, and say “Aww.”
But child-rearing in birds is stranger than you think.
I now have four-count-’em-FOUR nests to update you on! (Of course my plan was to have twenty or so, but hey, I’ll take what I can get.)
New nestlings! Read on for more. Photo by M. LaBarbera.
We found nests! And they have eggs in them!
The first nest we found belongs to OLLA (female) and ALGE (male). Or, we assume it belongs to ALGE too, since he and OLLA are mates; only genetic testing can tell us if the eventual chicks are really his.
Mom OLLA
Almost all birds incubate their eggs: keeping them warm while the embryo develops into a chick. In order to transfer heat better from their body to the eggs, many birds develop brood patches (a.k.a. incubation patches). The bird loses feathers from her belly, and the bare skin becomes wrinkly and swollen with fluid. In juncos only the female develops a brood patch, since she does all the incubating, but in species where males also incubate, males can develop brood patches too.
White-crowned Sparrow with a brood patch that is beginning to show edema
Tough Little Birds 