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Wildlife numbers on the decline in Southwest Colorado, plummeting worldwide

Species threatened locally include Gunnison sage-grouse, Townsend’s big-eared bat and Humpback chub
One of three lynx seen in March 2015 just north of Molas Pass. (Jerry McBride/Durango Herald file)

Wildlife populations worldwide have plunged an average of 69% since 1970. That was the staggering conclusion of the Living Planet Report 2022 released by the World Wildlife Fund earlier this month. The report is based on an analysis of 32,000 monitored populations of vertebrates (mammals, birds, amphibians, reptiles and fish) that included 5,230 species from 1970 to 2018.

The numbers are not as dire in Southwest Colorado, according to biologists and wildlife managers with Colorado Parks & Wildlife’s southwest region, but local wildlife is facing many of the same threats listed in the report.

“We have seen declines in a number of species for a number of different reasons whether it’s human population increases, development of a lot of our private wildlife habitat ranges or wildlife habitats for conversion into houses and subdivisions, and oil and gas development,” said Jamin Grigg, senior terrestrial biologist for the CPW’s southwest region. “Those have certainly been a huge factor. And drought and climate change has been a huge factor that’s impacting a number of populations.”

The main “drivers” in biodiversity decline mentioned by the report were habitat loss (from urban development, agricultural operations like logging and farming), mining, species over-exploitation, invasive species, pollution, climate change and disease.

The biggest decline in wildlife populations, 94%, is in Latin America and the Caribbean, according to the report. As well as an 83% decline in freshwater species globally.

“It did mention that declines in North America have been somewhat less than (the 69%) which is encouraging,” Grigg said.

The report lists a 20% decline in wildlife in North America, with the caveat that impacts to species and habitats before 1970 left biodiversity in North America no more intact than anywhere else in the world. The report also concludes that overconsumption and pollution in North America and other industrialized regions contribute to the steep decline in less developed regions.

“One thing that I would highlight is the North American model of wildlife conservation,” Grigg said. “I think that has probably helped us to address some of those declines. A lot of countries really don’t have any type of wildlife conservation model in place, and that has really hurt wildlife population conservation in a number of countries.”

The North American model largely relies on investing the monies collected from hunting and fishing licenses into conservation.

“So it directly pays for habitat conservation, biologist jobs, game warden jobs and wildlife manager jobs,” he said. “I think that’s been really beneficial and it’s helped us stave off or lessen some of those population declines.”

The State Wildlife Action Plan (SWAP) is the guiding document for conservation teams and Colorado Parks and Wildlife. Colorado’s first SWAP, completed in 2006 identified 210 “Species of Greatest Conservation Need.” Those species were grouped into two tiers. However, prioritizing conservation for tier one species proved “confounding” in the years that followed, which led to a redefining in the 2015 revision of SWAP. The revised Species of Greatest Conservation Need list of vertebrate animals and mollusks contains 159 species, but recognizes the species dropped from the list are still a concern.

Three young moose graze around mine ruins near Cunningham Creek northeast of Silverton. (Jerry McBride/Durango Herald file)

Species in Southwest Colorado that made the list include the Gunnison sage-grouse, Gunnison prairie dog, lynx, Townsend’s big-eared bat, Colorado pike minnow, Colorado River Cutthroat trout and the Humpback chub.

CPW biologist and wildlife managers are currently seeing declines in mule deer populations and some big horn sheep populations. But there have also been some longer-term success stories.

“Moose is one example,” said Matt Thorpe, deputy southwest regional manager for CPW. “They were historic to Colorado, but starting back in probably the ’80s we started bringing them back, including transplanting them to the Creede area. Now there’s a rough population (in multiple areas of Southwest Colorado) of 450 to 500 animals.”

Peregrine falcons are recovering. As are a small population of river otters. They were nearly wiped out but have been reintroduced to the Dolores River where they have been successful so far.

Wildlife populations are counted in a multitude of ways depending upon the species. While flyovers may work in part for herd species, that same method won’t work for bears. The bear population rises and falls based on the availability of forage. And bear counts are based on a multitude of markers and estimation.

“I started as a game warden in the late ’90s, and I think at the time we estimated our statewide bear population was around 12,000, whereas currently we estimated between 17,000 and 20,000 across the state,” Thorpe said.

Human encroachment into bear habitat has led to more confrontations, which creates another challenge to the preservation of their numbers.

Pinning a percentage of overall wildlife decline in Southwest Colorado is difficult.

A family of bighorn sheep graze on the exposed slope near Coal Bank Pass. The collar on the sheep is a radio transmitter that allows wildlife biologists to track the animal’s movements. Advocates for bighorn sheep say domestic sheep grazing in the Weminuche Wilderness puts bighorn at risk of contracting disease, which could potentially wipe out herds. (Jerry McBride/Durango Herald file)

“It’s a big question that’s going to vary dramatically from species to species, even from herd to herd, or population to population,” Grigg said.

Brad Weinmeister, southwest regional biologist for CPW, wants the public to think about it in another way.

Prairie dogs are essential to the ecosystem food chain, but can also be a costly pest for La Plata County ranchers. (Jerry McBride/Durango Herald file)

“Loss of habitat is really what’s driving this,” he said. “The animals don’t have a place to live. Obviously, we are seeing that in this area, so it is a concern. A lot of our time is spent trying to minimize or mitigate that loss of habitat and keep these animals going.”

Weinmeister challenges people to be aware of the kinds of impacts they have on wildlife and to take steps, no matter how small, to lessen that impact.

“People might say I don’t hunt and I don’t spend time in the woods so I don’t impact wildlife,” he said. “But you might drive down Highway 160 at seven in the morning and at deer crossings there are carcasses lined up along the highway. Just slowdown 5 or 10 miles an hour and you might be able to avoid that deer and fawn.

“Or maybe it is just going to a trailhead and seeing that it is closed for the winter because of mule deer winter range, and turning around and going someplace else to ride their bike during the wintertime. I challenge people to do that.”

The biennial Living Planet Report 2022 is a collaboration between two major conservation organizations, the World Wide Fund for Nature, widely known as the WWF, and the Zoological Society of London. The full report is available at https://wwflpr.awsassets.panda.org/downloads/lpr_2022_full_report.pdf

gjaros@durangoherald.com



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