Naturally Speaking

—by Steve Lekwa

Some people have asked me "where are the birds" this winter. A few have told me they think that it must be hawks that are eating all of them. I regret that I may be at least partly to blame for this theory. I featured some of our native and migratory birds of prey in a recent column and mentioned how their presence has helped to make the local flock of English sparrows very skittish around my bird feeder.

Cooper’s hawks are year-round residents in our area now, and are joined in winter by a few smaller sharp shinned hawks. They do feed on birds and will sometimes hunt near bird feeders where they can more easily find their prey. Predation has always been there at some level in populations of wild creatures, though. The world would be inundated with mice if it were not so. Songbirds and game birds, too, have always been subject to the presence of predatory species. Given appropriate habitat and suitable weather for nesting and rearing young, they have always lived in a relative balance with the native birds and animals that prey on them.

Balance is the key for all to survive. Predators can’t reduce their prey populations too greatly or they suffer the consequences and they decline, too. Humans have altered the factors that maintain the necessary balance, though. We create new habitats, destroy old ones, and alter others to suit our needs with too little thought given to how those actions affect the other living things that share the land with us. Our use of the land tends to follow the dollar, and our own profit, comfort, and convenience tend to dictate what we do.

We continue to introduce new and alien species either by accident or because we thought we might benefit in some way by their presence. Those introductions often have unforeseen and dramatic negative affects on the balance that sustains our native plants and animals. Introduced common carp have destroyed habitat for native plants, animals, and fish in lakes, rivers, and wetlands. We should have learned our lesson about carp decades ago, but several new species of Asian carp are now spreading destruction in American waterways (including here in Iowa) after accidental releases. Habitat alterations and the replacement of wandering herds of bison and elk by fenced in herds of cows have left cowbirds as local residents rather than wanders following the wild herds. They now parasitize and destroy reproduction in a far greater percentage of nests than they once did. Domestic cats have been cherished pets for centuries, but their spread around the world has had devastating affects on native birds and wildlife wherever they become established. Domestic cats and their numerous feral relatives kill as many game and songbirds as all the hawks and other native predators combined.

Weather is another factor that influences how many birds we see at our feeders and elsewhere. There hasn’t been a great deal of snow so far this winter, and except for the early part of the month, it’s been fairly mild. Natural foods have been easier to find and the birds haven’t needed our handouts as much. The truly nasty wet and cold weather we had last spring combined with late summer’s drought and heat to reduce the reproductive success of many of our birds. Some nests were destroyed and it may have been difficult for birds to find enough insects to successfully feed their young.

Game and songbirds have the reproductive potential to rebuild and maintain healthy populations in spite of ongoing losses to weather and predators. That can happen only if they have access to appropriate habitat and appropriate weather to utilize it, though. We can’t control the weather, but we can create and restore suitable habitat in our yards and on our farms if we have the will to do so.