Backyard Eggs

"Would you be willing to donate an egg or two to science?" I asked Hayley, the Museum's Assistant Director. Hayley has a flock of backyard chickens at home and I was wondering if their eggs are stronger than store-bought eggs. Luckily she was willing to sacrifice a few for the raptor program demonstration.

After meeting Aldo the American Kestrel during each live raptor program, we take a look at the problems associated with DDT that their cousin the Peregrine Falcon faced in the mid-1900's. DDT was fantastic at killing pesky insects, but it also thinned the falcon's egg shells so much that the eggs broke during incubation. 

"I made an omelet for breakfast this morning," I tell the audience. "And those eggs were pretty easy to crack. If eggs are already pretty fragile, maybe we didn't have too much of an impact on the birds." So I set up the Egg Smasher for a science experiment: how much weight can a healthy egg hold? We slowly add weight to a chicken egg until it breaks.

Normally I use a store-bought egg from a commercial farm. When my 35-pound box of rocks doesn't break the egg, I start using children of increasing sizes to sit on the egg. The egg finally cracks, with a gasp from the audience, under 60-90 pounds of weight. On average, I would say most eggs hold around 80 pounds, while I've had a handful of eggs hold over 100 pounds during this demonstration. 

During the last two programs, we tested Hayley's home-grown eggs. They held around 90 and 95 pounds before cracking, which is on the higher end of the average range. Good job, chickens!

Chicken eggs are approximately the same size as Peregrine Falcon eggs, so they should hold the same amount of weight. "A female Peregrine Falcon weighs 2 pounds. Her weight was enough to break her eggs," I explain to the audience once everyone recovers from the excitement of the egg smashing. "Did we have a big impact on those birds? Did we mean to?" Eggs are stronger than you would think, so yes, we had a huge impact! Eggshell thinning happened because we were spraying a chemical that solved one problem for us - it killed insects. But we didn't realize what other effects it would have in the environment. Luckily we figured out the problem and DDT was banned in Wisconsin in 1970 (largely thanks to Lorrie Otto's efforts, whom our owl is named after) and nationwide in 1972. With help from a reintroduction program, Peregrine Falcons could come back to Wisconsin.