Will Bird Flu Outbreak Save Denver Geese From Getting Whacked?

The last few years have been extremely tough for Denver geese.

In 2019, Denver Parks & Recreation decided to "disappear" a bunch of them for population-control purposes. And the following year, Parks & Rec engaged in another culling operation. There haven't been any such programs since.

But just when Denver geese thought it was safe to poop all over the grass again, a new life challenge showed up: Highly Pathogenic Avian Influenza, aka HPAI, a recent strain of which has been killing birds around the globe.

"It spreads between any of the birds that are out there," says Scott Gilmore, deputy executive director of Denver Parks & Rec. "This is probably one of the most significant years that I've seen."

This strain of HPAI has been present in Colorado since at least March 2022 and has already led to the deaths — or euthanasia — of over 6 million chickens. Countless wild birds, such as geese, have died from bird flu, too, over the past year.

This specific strain is deadlier than past strains of bird flu, with a mortality rate of close to 100 percent. The flu hasn't spared geese in Denver's parks; Parks & Rec is getting reports of a few dead geese every couple of days.

"There are sporadic reports — but then, these are just the reports that I'm receiving. Who knows what other people are seeing and not reporting?" says Vicki Vargas-Madrid, the wildlife program administrator at Parks & Rec. "Not every goose are we able to pick up. As these geese are dying from avian flu, many of them are just being left out in nature, because we can’t get out to every single one. A lot of them are out on the ice and in areas where we just can’t get to them."

So what does all of that mean for Denver's resident geese population when it comes to potential culling later this year? Signs are heading in a positive direction, as the ravaging of the bird flu probably helps their case in avoiding the gallows.

"I would definitely say it’s going to have an overall impact on the goose population. Will it help us with our overall geese management plan, which is to keep our geese populations to our objectives? It’s just hard to say right now, because we don’t have that data," Vargas-Madrid says. "But I will say that I think it will minimize the number of geese that are in our parks for now." And fewer geese means that there's less of a likelihood that another culling needs to happen.

There are two main categories of geese in Denver. Migratory geese come in the fall and winter and typically depart as the weather starts to warm up; they're the transplants. The other category is resident geese, those who are likely born and raised in Denver and do not migrate.

Culling operations don't focus on transplants, since they're just passing through. The operations, which take place in the summer, instead aim to lower the population of Denver's resident geese.

Back in 2019, before the controversial goose culling that summer, Parks & Rec calculated that the city's resident goose population was about 6,000 across the park system. Through a culling that summer and a second culling in the summer of 2020, Parks & Rec believes that the resident goose population is now 35 to 40 percent of what it was prior to the start of the culling. It has remained steady at that level — which would be 2,100 to 2,400 resident geese — since 2020, according to Parks & Rec.

"To be honest, it’s more successful than I ever hoped," says Gilmore. "The way it’s going now, I don’t see us having to cull geese. I don’t see us in the near future having to cull geese. I’m not saying we’ll never do it in the city, because it has worked."

Meanwhile, the overpopulation of geese can have a major effect on the parks system.

"Damaging our turf and complaints from the public about feces, and so many where they are in the same areas where people recreate in our parks. Water quality in our lakes. Wildlife diseases. All of those factors we look at," says Vargas-Madrid. "The critters start to compete for that same habitat. So the quality of habitat that we have is degraded because we see that competition."

Although culling is unlikely this summer, the city still works to keep geese in check.

Staffers often deploy the "Goosinator," a remote-controlled machine painted to look like a fierce predator. The machine is used to shoo geese away from parks and golf courses in what's known as "hazing." Parks & Rec also oils goose eggs during the spring to prevent them from hatching.

All of these strategies prevent the need to cull in the summer, according to Vargas-Madrid.

"I think we’ll be good, but you just never know," she says.