The good habitat Iowa provides for huge flocks of geese is causing trouble up north. Guy Zenner, a waterfowl biologist with the Iowa Department of Natural Resources, says the population of several types of geese has swelled, and vast numbers of birds are destroying parts of Canada.Studies find the winter populations of lesser snow geese and Ross’ geese have more than tripled in the past 30 years, from about 800-thousand to more than 2-point-6 million. Zenner says the birds spend their winters in Iowa and live too well off the land while here, then they devastate Canadian marshes when they return by eating all of the water plants.He says we’ve provided them with an unlimited food source, which improves their survival rates and their bodies so they can breed more successfully. Zenner says Iowa hunters can help the situation by thinning down the flocks.Zenner is based at the D-N-R’s Clear Lake Fish and Wildlife Station.