Invaders

I remember well my first view of East Point at Banner Marsh. It was a fall morning, with the classic blue sky, blue water, and brilliant colors of the season. Egrets, herons, ducks and geese flew through the landscape. Killdeer and redwing blackbirds raised the alarm as I drove by. Sparrows and tree swallows fluttered everywhere, with woodpeckers drumming in the distance. And a group of calm elegant white swans floated lazily near the road. I thought I had found Paradise.

Recently my neighbor Lynne stopped by to tell me she had visited Banner for the first time, and like me she was enchanted. She was particularly intrigued by those beautiful large white birds… the swans. The marsh magic had touched her even on a bleak February day.

Unfortunately, I have ambiguous feelings about those pesky swans. They are truly beautiful animals. As they arch those long necks back they look regal, but usually that means they are really pissed off about something and are ready to attack.

The swans at Banner are European mute swans. They have bright orange bills and are generally silent. Our native species include tundra swans and trumpeter swans, both of which have black bills and distinctive calls. Trumpeter swans are the largest of the native swans yet they are an endangered species. Release programs are in place to try and increase their numbers.

One bright spring morning I noticed a lone swan on the road at East Point, honking piteously. He was a lost trumpeter. His red neck band named him “P40”, which the state conservation officer later told me meant he was from Iowa. The local mute swan was not pleased by his presence, since his mate was nesting across the lake. For two weeks I watched that mute swan harass the trumpeter, who was chased down the road, on the water and in the air.

Toward the end of that time, the mute swan eased off a bit: he would allow the trumpeter a sip of water as long as his feet stayed on the road.

But the damage was done and the trumpeter left to find a friendlier haven.

Observing the interactions of these swans tried my patience and objectivity as a photographer. After the first fierce onslaught I wanted to throw a rock and bean that mute swan on the head. I’m still not sure I was right to resist that impulse.

Wildlife biologists know the mute swans compete with native geese, swans and ducks for habitat and food resources. They have probably contributed to the decline in numbers of several of these native bird species. My Audubon friends secretly harbor plans to eradicate all mute swans from North America: when the adults molt and before the young can fly, their plan is to “round ‘em up and move ‘em out”. The feeling about swans among birders is strong enough that they think it would be easy to get a few thousand volunteers to walk the marshes in a summer swan rodeo. Hey, if we can eradicate smallpox from the world, why can’t we eliminate mute swans from the continental US? You get the drift.

Unhappily, the swan problem is just a short chapter in the saga about the struggle to manage the increasing numbers of invasive species that threaten native ecosystems worldwide. The list of these newcomers is long and includes, in Illinois, such pests as the Asian carp, garlic mustard, gypsy moths, starlings, zebra mussels, and ninety percent of our earthworms. (I don’t seem to worry about the worms.) All contribute to the decline of native species by competing successfully for space and food resources . In 1991 the U.S. fish and wildlife Service estimated that one hundred and sixty species officially listed as threatened or endangered owed their status in part to competition with or predation by non-native species.(1) Biologist Edward O. Wilson has claimed the introduction of alien critters, plants and microbes is second only to habitat destruction as a leading cause of extinctions worldwide. (2)

The Darwinist in me wonders if we should care at all. Perhaps we should let natural selection take its course, where only the fittest survive. I think my unease with the "live and let die" solution is that it is a question of time. Animals and plants have certainly been moving about the planet for millions of years, carried by tsunamis, hurricanes, or tornadoes and the like. But in the past movement has been slow, and native ecosystems have had time to evolve a response to the challenge of the invaders. We are at a point in history where large numbers of species are becoming extinct in a very short period of time due to human activities. The last comparable rate of extinction occurred when some cataclysmic event killed off the dinosaurs 65 million years ago.

Surely, the least we need to do is to save preserves of native ecosystems until we can figure out a wider strategy to save species diversity and the gene pool. So I vote to move or murder the mute swans at Banner for the greater good. Now, how can we get rid of those noisy starlings and quarrelsome house sparrows?

1. Alan Burdick, Out of Eden, An Odyssey of Ecological Invasion. Farrar, Straus and Giroux, New York (2005).

2. Edward O. Wilson, Naturalist. Island Press/Shearwater Books, Washington, D.C.(1994).