Noteworthy news has been coming thick and fast on the puma recolonisation front in the American Midwest.

The first confirmed female mountain lion in Iowa. Image: Iowa Department of Natural Resources/Twitter

Last Tuesday, officials with the Iowa Department of Natural Resources killed a puma (aka cougar or mountain lion) in west-central Iowa: the first female confirmed in the state in more than a century. The ill-fated cat was suspected in the killing of a domestic calf earlier in the month.

Two days later, meanwhile, and a few states eastward, wildlife officials authenticated recent photos of a puma on Michigan's Lower Peninsula, the first in modern times. (Numerous cougars have been documented in the state's Upper Peninsula, a more rugged, forested and sparsely populated region separated from Lower Michigan by Lakes Michigan and Huron.)

In the Iowa incident, near the town of Galva, a DNR officer responded to an emergency call after dogs treed an 88-pound female puma on a farm. Ultimately, a decision was made to euthanise the animal because of the recent depredation and its proximity to people.

"Generally we like to leave mountain lions alone, but once there are concerns about human and livestock safety, lethal action is taken," Iowa DNR biologist Vince Evelsizer told the Sioux City Journal. "[The officer] had to make a decision on what to do with it. There were concerns about human safety."

Pumas were killed off in Iowa by the late 19th century, but the state – like many others in the Midwest – has seen its fair share of recent big-cat drifters. According to the DNR, there have been 21 confirmed mountain lions in Iowa since 1995, and four cats have been killed since 2013 (the species has no special status in the state). 

Most of these animals have been males, which jibes with typical puma behaviour: male youngsters tend to disperse from their home turf, commonly traveling 90 kilometres (56 miles) or more in search of greener pastures (which partly means avoiding inbreeding).

Recent years have seen some spectacular journeys undertaken by male cats wayfaring eastward from established puma strongholds in the western US – none more epic than a 140-pound (64kg) lion that covered more than 2,414 kilometres (1500 miles) from the Black Hills of South Dakota, only to die on the Wilbur Cross Parkway in Milford, Connecticut. 

St Croix Cougar_2017_07_04.jpg
Dubbed the "St. Croix Cougar", the big cat covered thousands of kilometres on its ill-fated trek. Trail cameras occasionally snapped the puma along the way. Image: Wisconsin Department of Natural Resources

DNA tests and remote-camera photographs confirmed that the puma had passed through Minnesota, Wisconsin and New York State on its two-year trek to the East Coast, suggesting it likely slipped across the international border via Upper Michigan into Ontario en route. 

Another Black Hills male puma travelled some 1,287 kilometres (800 miles) to meet a similarly abrupt and bizarre end in Chicago, where it was shot by police officers in a residential neighbourhood on the city's North Side.

Young female pumas are much more likely to stay closer to home, but a minority strike off for bigger horizons. And some of those, as it turns out, aren't slouches when it comes to covering ground either. A 2008 study documented the longest-known dispersal for a female cougar: 1,341 kilometres (833 miles) between Utah's Oquirrh Mountains and Colorado's White River Plateau, an adventure that had her crossing four major rivers and an interstate highway.

Dr Michelle LaRue, executive director of the Cougar Network and a research ecologist at the University of Minnesota, agrees that the sex of the Iowa puma is significant, and also aligns with what appears to be a recent trend. 

"Anecdotally speaking, we're seeing more evidence of female cougars in the Midwest," she says. 

Among them was a female documented in southern Missouri last year. Analysis of saliva she conveniently left on an elk carcass showed the cat hailed from established cougar populations in the western US. 

There's still a chance the Iowa female was a released (or escaped) captive animal, but odds are it's a wild disperser. The Iowa DNR's necropsy of the carcass will include genetic testing, which should confirm the cat's origins. 

The nearest breeding puma population to west-central Iowa inhabits the Niobrara River Valley of northern Nebraska, a state recolonised by the big cats in the 1990s. Another possibility is that the cat hailed from the Black Hills of South Dakota, which supports some 250 pumas and serves as an important eastern outpost for the species in North America.

A wild mountain lion filmed in the Black Hills of South Dakota, where around 200-250 of the big cats roam.

Research by LaRue and Dr Clay Nielsen of Southern Illinois University Carbondale has highlighted dispersal corridors as well as promising, if scattered, blocks of highly suitable habitat for pumas in the Midwest. "Highly suitable" in this case basically means large swathes of deep forest and not many people. Large expanses of the Midwest (Iowa is a case in point) are given over to farmland and pasture: low-quality habitat for pumas, though wooded or shrubby watercourses can be effective dispersal corridors through such landscapes. 

LaRue notes that when it comes to recolonising the region, the cats seem to follow a "stepping stone" strategy: skirting through marginal country until some of them reach suitable habitat, which may eventually come to support an outpost population (and give rise to the next journeying generation).

Of course, this requires females to be part of the puma vanguard – and the question for LaRue is whether they're up to it: "Are females likely to disperse far enough away from mom's territory to be able to potentially establish a population in the Midwest?"

Alongside confirmation of female pumas out and about in Iowa, Missouri and other central states, some of the latest research LaRue and her colleagues have conducted seems to suggest that the answer is yes. In a paper published last year, the researchers found that most of the larger patches of highly suitable habitat in the Midwest would indeed host at least some pumas – including females – within 25 years. (This was true even when their research models allowed for cougar hunting in the nearest source populations.)

Despite its mostly rural nature, Iowa doesn't have much in the way of "highly suitable" puma turf, though LaRue and Nielsen's research showed pockets in the northeastern corner (which, with its bluffs and ravines, harbours rougher country than the rest of the state). "There is good habitat [in Iowa]," LaRue acknowledges, "but there isn't very much of it."

The mountain lion in Michigan was photographed by a motorist who spotted the big cat in the shine of his headlights. Image: Michigan Department of Natural Resources

Confirmation of the puma in Lower Michigan, meanwhile, came via night-time pictures taken in June by a motorist who spotted the big cat in the shine of his headlights.

As with the recent Iowa case, wildlife managers are cautioning that they don't yet know the puma's pedigree. "There is no way for us to know if this animal is a dispersing transient from a western state ... or if this cat was released locally," Kevin Swanson of the Michigan DNR said in a news release.

The Cougar Network maintains an interactive map of confirmed puma sightings in central and eastern North America since 1990, and also invites folks to submit photos or other evidence (not reports alone) of pumas outside their normal range. 

And speaking of maps, the Nebraska Game and Parks Commission has another cool one online showing established puma territory, confirmed sightings and suitable habitat in the state – interesting context for reflecting on the Iowa cat treed not too far from the Nebraska border.



Top header image: ltmayers/Flickr