I crawled under the porch to remove some debris and pull some weeds, and while I was there, I reached up to remove an old bird's nest from a piling. The nest had been there for at least a month or two and I expected that the young were hatched and gone.
To my surprise, I found myself looking down at one beautiful robin's egg. I showed it to Griffin and Georgi and put the nest back. I hadn't seen a robin near the nest since it was built. Was the egg abandoned or was the mother away for the moment?
I also found faded, brittle remains of another egg on the ground. It appeared to have hatched.
A week went by and there was no sign of a mother. What I had gathered about robins in the meantime (hypotheses below) led me to believe this egg had been abandoned, so I took the nest down and Griffin and I studied it and finally brought it to his classroom today, where the children are enjoying observing it. Griff tells me that somebody accidentally poked a tiny hole in the shell and they're pretending the egg is hatching. I wonder what's actually inside that shell.
What we learned about robin's nests:
- American Robin nests are composed of grass and twigs, held together with mud and lined with fine grass. Paper and feathers are also often found in the nests.
- robins usually have 2-3 broods during mating season. Clutches range from 2-5 eggs, usually 3-4. Each new brood is raised in a new nest.
- robins sometimes build multiple nests simultaneously and might lay 1-2 eggs in each before selecting one nest, laying more eggs, and incubating them.
- nest built on porch piling (under deck, ~3' off the ground)
- no adult birds observed in vicinity of nest over several weeks
- open cup-shaped nest composed mainly of grasses with some twigs and mud
- nest also includes a length of rope or shoelace, one paper/wire twist tie, a bit of green plastic thread, a scrap of paper, and at least two other small plastic scraps
- single "robin's egg blue" egg in nest; appears undamaged
- faded, brittle shell found several feet from nest on the ground
- this might have been one of several "tester" nests created by a female robin; this nest and egg may have been abandoned in favor of another nesting location; the shell on the ground might have been an additional abandoned egg that was consumed by a predator or removed from the nest and destroyed in some other manner
- the nest might have been home to a successful brood;the shell on the ground might have been a sibling egg that hatched; this egg might have been infertile or the chick inside might not have developed properly and died
- the egg/nest might also be unrelated to the shell fragments found on the ground**
** I questioned whether to use "may" or "might" in my hypotheses section. I had initially used "may" and it seemed somehow wrong, while "might" seemed more fitting. I then googled around to see what, if anything, the grammarians of the world had to say about may vs. might. My survey can best be summed up by this blog comment:
Might applies to what is possible; may to what is permissible.