Orphaned Nestlings (Shallow Thoughts)

Akkana's Musings on Open Source Computing and Technology, Science, and Nature.

Tue, 02 Jul 2019

Orphaned Nestlings

Yesterday afternoon I was walking up the path to the back door when I noticed a bird's nest on the ground. I bent to examine it -- and spied two struggling baby birds on the rocks next to the nest.

[Orphaned nestling baby birds, gaping for food] I gently picked them up and put them back in the nest. Then what? On the ground there, they'd be easy fodder for coyotes, foxes or any other predator. But the tree it must have fallen from is a tall blue spruce; the lowest branches are way above head height, and even then I couldn't see any secure place to put a nest where it wouldn't immediately fall down again.

I chose another option: there's an upstairs deck immediately adjacent to that tree, so if I put the nest on the corner of the deck, it might be close enough to its original location that if the parents came looking for the nest, they'd be able to hear the chicks' calls. I've always read that parents will hang around and feed nestlings if they fall from the tree.

Nice theor; but the problem was that the chicks were too quiet. When they felt the nest jiggle as I moved it, they gaped, obviously wanting food; but although they did make a faint peeping, it wasn't loud enough to be heard from more than a few feet away.

Nevertheless, I left them there overnight, hoping a parent would find them in the evening or first thing in the morning. The deck is adjacent to my bedroom, so I was pretty sure I'd hear it if the parents came and fed the chicks. (It's easy to hear when the Bewick's wrens in the nest box above the other deck come to feed their chicks in the morning.)

Alas, there was no reunion. I heard no sounds and saw no activity. The chicks were still alive and active in the morning, but obviously very hungry, gaping every time they heard a noise. I wanted very badly to feed them, to find a bug or a little piece of steak or something that I could put in those gaping hungry mouths, but I was afraid of feeding them something that might turn out to be harmful. As it turned out, that was the right decision.

It was time to call for help (I'd posted on our local birders' list the evening before, but no one had any useful advice). Fortunately, we have an experienced bird rehabilitator in town, whom I know slightly, so I called her and got the okay to bring them in.

[Orphaned nestlings, now warm and fed] She weighed the babies (roughly 17 and 14 grams), put them on a heating pad and gave them a little pedialite solution. She said she couldn't actually feed them until they pooped; if I understood correctly, baby birds can get backed up and if you feed them then, it can kill them. Fortunately they both pooped right away after getting a drink, so she mixed up some baby bird formula and fed them with an eyedropper.

You know how parent birds always seem to shove their bill all the way down the chick's throat while feeding them? It always looks like they'd be in danger of puncturing the chick's stomach, but it turns out there's a reason for it. Much like humans, birds can have food going "down the wrong pipe", down the trachea or breathing tube rather than the esophagus or food tube. Unlike humans, birds don't have an epiglottis, the flap that closes over a mammal's trachea to keep food from getting in. When adult birds eat (I looked this up after getting home), the opening of the glottis closes during swallowing; but when feeding baby birds, you have to insert your eyedropper (or your bill, if you're a parent bird) well past the entrance to the trachea to make sure the food doesn't go down the breathing tube and drown/smother the chick. It takes training and practice to get this right, and sometimes even experienced bird rehabilitators get it wrong. So it was a good thing I didn't start randomly dropping chunks of food into the nestlings' mouths.

Sally wasn't any more able to identify the nestlings' species than I was. One possible suggestion I had was ash-throated flycatcher: they're about the right size, we have several hanging about the yard, and one had been hanging around that area of the yard all day, pestering the Bewick's wrens feeding their young in the nest box. I thought maybe the flycatchers wanted the nest box for their second nest of the season; but what if the flycatchers, normally cavity nesters, hadn't been able to find a suitable cavity, had tried building a nest in the blue spruce and done a poor job of it and the nest fell down?

It's a nice theory; but Sally showed me that these nestlings have crops (bulging places by their mouths where they were storing food as they ate), which apparently flycatchers don't. She said that's why flycatcher parents are so harried -- they're constantly on the move catching bugs to feed to their chicks, much more than most birds, because the babies can't store food themselves.

[The nest that fell] They could be canyon towhees or juniper titmouse; the bird rehabilitator guides didn't those species so it's hard to tell. Or they could be robins or even bluebirds, but I haven't seen many of either species around the yard this summer. They seem too big to be house finches, wrens, chickadees or bushtits.

The construction of the nest might give some clues. It's a work of art, roomy and sturdy and very comfortable looking, made of tansy mustard and other weeds and lined with soft hair. Maybe I'll find someone who's good at nest identification.

Anyway, for now, their species is a mystery, but they're warm and fed and being well cared for. She warned me that nestlings don't always survive and sometimes they have injuries from falling, but with any luck, they'll grow and eventually will be released.

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[ 15:40 Jul 02, 2019    More nature | permalink to this entry | comments ]