By Dr. Robert Thorson
Warning: This column is not for the squeamish. Those with weak stomachs are advised to stop eating before reading.
When it comes to invasive species, my least favorite is the Canada goose (Branta canadensis). Their raucous flocks used to be a powerful symbol of seasonal rhythms and wildlife migration. Now they’re a harbinger of droppings of the ghastly, greenish white, totally nasty, curled-at-the-end variety that, when dissolved, turns our ponds into black lagoons.
An ecologist may not consider geese an invasive species because they’ve been migrating up and down the Atlantic flyway for millenniums, stopping in New England on their way as if checking into a bird motel. But I consider them invasive because they’ve invaded and corrupted our lawns, ponds and streams. This is true for much of America and northern Europe as well.
A few geese are nice to have around. But the hundreds that occupy many small ponds and the millions that migrate along the Atlantic flyway pose a serious problem. They bite, especially when annoyed. They threaten aircraft. They enrage farmers by destroying crops. They tear up lawns, increasing the land’s vulnerability to erosion. But the main problem with geese is their droppings. A single adult goose can ingest up to five pounds of grass each day, leaving a pound and a half of excrement in exchange.
The first problem with goose droppings is that they’re just plain disgusting. As a pedestrian commuter, I walk around Mirror Lake at the University of Connecticut, a typical goose-infested pond. Almost every day there is a gushy green gantlet of smears and plops on sidewalks and lawns. In winter, it stains the clothes of sledders. In early spring, it’s slime on ice. In summer, golfers use their irons as pooper-scoopers before they can putt. Fall is the best season for goose poop because there’s still some hope that the poopers will fly away.
The second problem with urban and suburban goose droppings is that they wash into the nearest gutter, drain, stream or pond. This pulse of bio-available nitrogen and phosphorous stimulates the growth of algae, which clouds the water before making it smell like a toilet. The overload of organic matter deoxygenates the water, especially near the bottom, converting it to a semi-dark, dead zone.
Third, too much excrement creates a public health hazard associated with microbial pathogens and, God forbid, perhaps even bird flu.
What finally prompted me to write about such awful stuff was a recent stroll by Mirror Lake. Floating in the gray murky water were thousands of floppy rafts of what looked like black felt torn from a single garment. The smell was awful, redolent with sulfur. The sample I collected was undercoated with brown silt, and it draped over my sampling stick as a filamentous slime. After discussing this with a local expert, we concluded that the pond had become so polluted that a mat of cyanobacteria (otherwise known as blue-green algae) had carpeted the shallow bottom before floating upward into our world.
I immediately thought of the old movie “Creature from the Black Lagoon,” a classic black-and-white monster film from the 1950s about a humanoid with gills. My next thought was of “The Creature Who Made the Black Lagoon.” That creature, of course, is the Canada goose, which thinks of Mirror Lake as a predator-free latrine.
It’s time to get rid of the goose nuisance, using some humane and practical method: removing eggs, sterilizing birds, rounding them up for euthanization or letting hungry people hunt them. The best methods will be case-specific and are best left to professional wildlife managers. Scaring them away only makes them excrete somewhere else.
What can you do? Support the notion of goose eradication even if a few wild geese are affected, and even if animal rights activists put up a fuss.
Otherwise, a pond near you might go the way of the black lagoon.