An investigation into paint ingredients found that limestone, a source of calcium, is
often a key ingredient in paint. Scientists theorize that Blue Jays are eating paint chips
for the calcium. Deborah Jasak and others found that offering eggshells, another good
source of calcium, stopped the paint-chipping behavior.
the Birdscope article was published, more reports came in, and new information
about the relationship between acidic soil and calcium availability in the northeast came
to light. An updated article, published in the January/February 2003 issue of Bird
Watcher's Digest, incorporates the new information and points out that Lab
scientists believe the Blue Jays are stashing away, or caching, calcium for spring.
Scientists theorize that the Blue Jays, especially in the northeast, may cache calcium
before the breeding season because naturally occurring calcium may be in short supply.
As snow covers the ground throughout much of the northeast during
the 2002-2003 winter, we are again hearing numerous reports of Blue Jays eating house
paint. If Blue Jays are chipping the paint on your house, consider offering them
eggshells. You can learn how to provide eggshells safely in our About Birds and Bird
Feeding Section (scroll down the What to Feed Birds
page to the section on grit).
You can learn more about calcium consumption in birds from research
conducted by the Lab in 1997 and 1998, as reported in BirdScope.
Learn more about the Lab's research on acid rain and it's effects on
breeding birds here.