SUMMER 2001/VOLUME 15, NUMBER 3

What Are Those Jays Eating?
By ANNE MARIE JOHNSON
Northeastern Blue Jays have a fondness for house paint


Blue Jays chipped and ate the paint off Deborah Jasak's house in Hopkinton, New Hampshire
Deborah Jasak
Jays may be known as marauding rascals, raiding other birds’ nests, monopolizing bird feeders, and otherwise creating mischief in the yard. But Deborah Jasak never expected to find Blue Jays chipping the paint off her freshly painted house. “It started around Christmas last year, just after the first snow. Every morning I would wake up to the sound of Blue Jays pounding on my house,” said Deborah, a longtime FeederWatcher in Hopkinton, New Hampshire. At first she thought the birds were cracking open seed shells or trying to get insects from behind the paint. By carefully observing the Blue Jays, she realized that they were actually flying to the ground, retrieving the paint chips, and, to her amazement, eating them.

Because of the damage to her house (see photograph above) Deborah wondered if she’d have to stop feeding birds. “But I was not going to let these Blue Jays keep me from enjoying my other birds,” she said. So with the help of staff members at seed stores, Audubon, and Project FeederWatch, she began experimenting to see what might satisfy her flock of 40 Blue Jays better than house paint. One by one, Deborah tried oyster shells, sand, dirt, and trace minerals. “The only solution that worked was eggshells—a whole lot of eggshells!” she said. Deborah offered two to three cups of shells per day, and every time the shells became buried under fresh snow, the Blue Jays would start nibbling on her house paint again.

After hearing of Deborah’s difficulties, we wondered if hers was an isolated case. Three more FeederWatchers from New Hampshire, one from Pennsylvania, and one from Wisconsin reported paint-eating jays. We also queried several Audubon chapters. Aside from Massachusetts Audubon and the Audubon Society of New Hampshire, none reported hearing about this Blue Jay behavior. But the stories from these two states were quite compelling.

Becky Suomala, the naturalist at the Audubon Society of New Hampshire, reported that every winter her office receives numerous inquiries about Blue Jays eating paint. “This past winter we had more calls than the winter before, probably because the snow cover lasted longer than usual. We had so many inquiries that we put the topic on our ‘Ask the Naturalist’ phone line and on our web site.”

Linda Cocca, a naturalist with Massachusetts Audubon, reported that the group’s Natural History Helpline receives a few calls each winter about Blue Jays eating house paint. However, in January 1996, Linda received more reports than usual, perhaps because of the heavy snowfall (100 inches of snowfall in Massachusetts that winter). She shared the information with a reporter from the Boston Globe, which ran an article the next day. Linda exclaimed, “Pandora’s box was opened! During the next three days I received 160 reports, mainly from people in eastern Massachusetts, who observed Blue Jays eating the light-colored paint on their house or garage.” Linda went on to say that providing eggshells seemed to stop the behavior.

From our inquiries, a pattern started to emerge: Blue Jays in the upper Northeast seemed to have a fondness for eating house paint during winter and an even stronger affinity for eggshells. This led us to many other questions.

How to Provide Eggshells Safely
Unsterilized eggshells may contain harmful Salmonella bacteria. Before providing eggshells, boil them for 10 minutes or heat them in the oven for 20 minutes at 250° F. Let the eggshells cool, then crush them into pieces smaller than a dime. Offer the eggshells in a dish or on a low platform feeder.

Why paint? Can paint, like eggshells, serve as a source of grit or calcium? Before Deborah provided eggshells, the Blue Jays chose paint over the other sources of grit that she provided. According to John Stauffer of the Paint Quality Institute, paint manufacturers have used calcium carbonate, or limestone, as an extender pigment in paint for hundreds of years, making paint a source of calcium.

Why Blue Jays? Using data collected by citizen scientists through the Lab’s Birds and Calcium Project, André Dhondt and Wesley Hochachka found that Blue Jays consumed more than twice as much calcium as other bird species. Furthermore, as will be reported in The Condor this fall, they found that Blue Jays, unlike other birds, continued to consume calcium throughout the summer and into fall. Research has shown that songbirds need calcium during the breeding season for egg laying and nestling growth but don’t store calcium in their bodies for use in egg formation. Dhondt and Hochachka suggested that Blue Jays might cache calcium in the fall for later use. However, Dhondt has since raised the possibility that Blue Jays have a unique and as yet unexplained need for calcium.

Why the Northeast? Could paint chipping be a foraging skill passed down from one generation of Blue Jays to the next? Or could the behavior be related to the lack of calcium in northeastern soils? Compared to other regions, northeastern soils are naturally poor in calcium. This deficiency is further exacerbated by the relatively high amount of acid rain there (hydrogen ions in acid rain leach calcium from the soil).

What to do. Providing eggshells clearly deters Blue Jays from eating house paint. Deborah’s flock of Blue Jays was so large that it took two to three cups of eggshells per day to satisfy it. She eventually enlisted the aid of a local baker who saved eggshells for her. “It’s a long way to go for the birds,” Deborah said, “but it was worth it.”

Fortunately, most of Deborah’s Blue Jay flock dispersed with the arrival of spring. The few that remain no longer consume many of the eggshells she puts out, and they are leaving her house alone.

For more on the Birds and Calcium Project, see the Spring 1997, Winter 1998, and Spring 1999 issues of Birdscope.


Suggested citation: Johnson, Anne Marie, What Are Those Jays Eating? Birdscope, newsletter of the Cornell Lab of Ornithology, Summer 2001. <www.birds.cornell.edu>

For permission to reprint all or part of this article, please contact Miyoko Chu, Editor, Cornell Lab of Ornithology, 159 Sapsucker Woods Rd., Ithaca, New York. Phone (607) 254-2451. Email mcc37@cornell.edu