Bird Watcher's General Store

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Egg Dumping

Dear Bird Folks,

For the past seven years I’ve had a family of chickadees nesting in my birdhouse. One year a Blue Jay hung on the little porch on the front of the birdhouse and proceeded to pluck out and eat the little chicks. I’ve since cut off the porch and that stopped that. This year, after starting a nest, the birds stopped coming. Someone in my bridge club suggested that I should check inside the box. When I checked I was surprised to find fourteen chickadee eggs inside. That’s a lot for one bird. What happened?

-Harold, Eastham, MA


I tried bridge, Harold,

I usually stink at card games, but when I heard that bridge has a “dummy” in it, I thought, “Now that’s the game for me.” I mean, even I should be able to beat a dummy. Right? Wrong. It turns out that the dummy is a misleading term for one of the hands in the game and not a description of an inept player, who I was hoping to play against. After that awkward experience I gave up playing card games forever and returned to something I am good at – shooting craps with my kids for their lunch money. That’s more my style.

Before I get to all those eggs I want address two other topics in your question. The first one has to do with monitoring nest boxes. The suggestion to look inside your birdhouse is a good one, even if it did come from a bridge player. I’m not going to dwell on this though, I harped on it a few weeks back and even I’m getting sick of hearing it. The other matter has to do with the “front porch” on your birdhouse. You and your chickadees found out the hard way that anything on the front of a birdhouse is a bad idea, including those stupid perfunctory perches. (You know that I’m serious when I use a word like “perfunctory.”)

I don’t know which idiot carpenter thought birds needed perches on all of their homes (probably a carpenter whose cousin owned a perch factory), but whoever it was he/she started a trend that has been impossible to stop. Think about it for a minute. When woodpeckers or chickadees hollow out their own nesting cavities in dead trees, they don’t add perches to them. Why? Because they’re lazy? Because their cousin doesn’t own a perch factory? No, because wild birds don’t need, want or use perches. They need nothing but a hole in the front of their home. The only creatures that use perches are predators. When buying or building a birdhouse forget the perch and forget the front porch. Don’t add a solarium, either (those went out thirty years ago).

About your mystery pile of fourteen eggs: That sure is an odd one. Hmm. How well do you know your chickadees? Do you know if they were going to a fertility clinic? Perhaps your birds were trying hatch out a ridiculously large family in hopes of getting on TV with Dr. Phil. Don’t laugh, it’s happened before. The probable reason for all those eggs is nearly as bizarre as my first suggestion. Your resident chickadee couple may have been victimized by a case of “egg dumping.” Egg dumping may sound like something that happens to a clumsy waitress at a diner or an incident the EPA should be involved in, but it’s actually a fairly common event in the bird world. Here’s what I think happened.

Your chickadees built their nest in your now porch-less nest box, just like they do every year. Nearby, another pair of chickadees built a nest in a different birdhouse or tree cavity. For a while everything was going swell for both pairs. But then something bad happened to the nest of the second pair just as the female was about to lay her eggs. Perhaps a predator discovered the nest, or our nasty June nor’easter blew over the nesting tree, or a fussy property owner had the nest tree cut down because it was dead and ugly, or she was kicked out onto the street when the bank foreclosed on her nest box. Whatever the reason, the panicked female had to quickly find a place to lay her eggs and your already claimed birdhouse was the best option she could come up with. While laying eggs into an occupied nest seemed like a good idea at the time it didn’t lead to one big happy super family of baby chickadees. It appears that both pairs abandoned the crowded birdhouse, and who can blame them? No sane chickadee couple wants to hatch and raise fourteen chicks, Dr. Phil or no Dr. Phil.

Most of the time egg dumping leads to negative results for the birds that are involved. However, the Wilson Journal of Ornithology (which I’m sure you read religiously) reported that one creative female Wood Duck laid her eggs in the nest of an Eastern Screech-owl after she had tossed out the owl’s eggs. The owl actually hatched the little ducks and even tried to feed them. That’s when the ducklings noticed that there was something odd about “mom” and got out while the getting was good and headed for the safety of the nearest water. Gambling for lunch money is one thing, but gambling when you might end up being lunch is never a good idea.