Sparse acorn crop may threaten squirrel population

Erin Holmes

Squirrels and other wildlife species found both on campus and in surrounding habitat areas may experience some hard times this winter due to an almost nonexistent acorn crop, said Paul Wray, professor of forestry.

“This year wasn’t really good for any of the oaks,” Wray said.

The main species on campus seeing harmful effects include squirrels and blue jays. Most people don’t associate deer, wild turkeys and wood ducks to share in the shortage, but they will see some of the side effects, said William Clark, professor of animal ecology.

The shortage is caused by the failure of a majority of Iowa’s oak species to produce a bountiful crop, Wray said.

Several reasons contribute to the loss of production. First, acorn production tends to be a periodical activity, Wray said. “Fairly good acorn crops are produced with anywhere from two to five years between them.”

Another contributing factor is excessive rainfall or cold weather experienced during the time period when the oak flowers, Wray said.

“A late frost can really reduce the crop to nothing,” he said.

For the red and white oaks found throughout campus, the flowering occurs in the spring. Depending on the type of oak, maturation occurs in the sequential fall or during the upcoming fall.

A final cause for the shortage are insects, primarily the acorn weevil, Wray said.

“You are not going to see big effects, but you will see real effects,” Clark said.

The body conditioning of the animals, mainly the squirrels, could see some harmful side effects.

“This could reduce reproduction in the following spring,” Clark said. “Females won’t be as big and fat because they would be coming out of winter in poor condition.”

Most of the other species besides the squirrels are capable of making adaptations.

“In terms of having much of a population effect, most of these species will do fine; they will just switch to other food sources,” Wray said. “Blue jays can migrate to the edges of corns fields and utilize their other food sources.”

As a species that can move, blue jays will reorganize themselves in terms of their distribution.

The shortage could lead to an insufficient supply of acorn seedlings for the next couple of years.