blue jays part 2: why are they chipping paint off my house?
RAT-TAT-TAT. And then again, from outdoors, on the front of the house. It’s far too early for the annual woodpecker ritual of drumming to assert territory; it’s winter, not breeding season. Was the same squirrel who’s been gnawing on the furniture on my back porch shifting focus (and had he somehow developed a rhythmic action to produce that sound)?
I sat in wait, determined to find out. The answer was a bit of a surprise:
It was a blue jay. And a few feet away, watching from a branch as the first bird chipped paint off a column on the porch, three companions cheered her on, as if awaiting their turns at bat.
But why? Maybe Google will know.
Though the original articles it refers to—from “Bird Watcher’s Digest” and Cornell Lab of Ornithology’s former membership publication “BirdScope”—are more than 10 years old and not online, this synopsis on Project FeederWatch provides the basic explanation:
Limestone, a source of calcium, is often an ingredient in paint (especially pale-colored latex paint birds prefer, apparently). The theory is that blue jays in the Northeast and Eastern Canada may collect and cache calcium in anticipation of increased needs in nesting season. Songbirds can’t store sufficient calcium in their bodies, and look to natural sources like snail shells, isopods including pill bugs and millipedes, and even earthworms—none of them easy to find right now.
(A related topic: In areas of high acid rain, those natural calcium sources have dwindled even when it’s not winter, posing a risk to nesting forest birds, such as ovenbirds, as appropriate habitat diminishes.)
How to discourage paint-chipping? Offer egg shells, the various online threads suggest, specifically after sterilizing them by boiling or heating in a 250F oven for 20 minutes, to prevent potential salmonella transmission.
Really? But yes, of course I’m game.
Within 5 minutes of placing three sets of empty, halved, sterilized shells on the snow in the vicinity of my bird feeder, they were airlifted away, one after another. And yes, by guess who? And then again the next time I cooked eggs, and the next…
With smaller pieces of shell, or the paint chips, or for that matter bird seed, they load up awhile before flying off to hide the stash, putting the bits in their pouch-like “crop” temporarily. That’s what the jay, above, is doing with those kernels.
How the blue jays figured out the paint-chemistry connection seems to be unknown, as is how they knew those eggshells were on their grocery list. But remember: They’re in the same family as crows, and crows are really smart, too. That was the subject of Blue Jays Part 1.