2nd documented case of grouse hybrid in North DakotaBISMARCK — In nature — and in the world of humans — there are anomalies.
By: Brian Gehring, The Dickinson Press
BISMARCK — In nature — and in the world of humans — there are anomalies.
In 2006, for example, bear hunters in Alaska killed what turned out to be a cross between a polar bear and a grizzly bear. While rare, hybrids between similar, but different, species do happen in the wild.
In April, a crew from the North Dakota Game and Fish Department captured video footage of a sharptail grouse/sage grouse hybrid on a dancing ground in northern Slope County.
It is the second time such a hybrid has been documented in North Dakota. The first was in 1984, also in Slope County.
Aaron Robinson, upland game biologist for Game and Fish, said that while sightings of the sage grouse/sharptail hybrid are rare, they are not unheard of. There was a cross collected in South Dakota about four years ago and a couple instances in Alberta, Canada.
“What’s uncommon is the documentation,” Robinson said. “There isn’t a lot of it out there.”
Robinson said there might have been sightings over the years but those involved either did not report them or possibly did not know what they were seeing.
The hybrid documented in 1984 was collected and now is on display at the Smithsonian Institution, said Stan Kohn, upland game supervisor for Game and Fish. The Smithsonian examined the bird and while it was found to have male reproductive organs, they were undersized and it’s likely the bird was sterile, he said.
Kohn said that in aerial surveys following that discovery, a number of sharptail grouse dancing grounds, or leks, were within about a half-mile of the sage grouse lek.
In the 1984 case, there were about 15 males on the sage grouse lek and in the most recent finding, only three, he said.
Habitats for the two birds are different: sage grouse rely on areas with thick stands of sage brush while sharptails prefer grassland areas.
The decline in the sage grouse population has been well-documented in recent years because of the loss of habitat in western North Dakota. Numbers haven’t been at a huntable level for several years, though this year’s survey showed an increase of about 15 percent over the previous year’s count. The population took a hit because of West Nile disease, a virus that can be carried by sharptails. However, sharptails seem to be more immune to it than are sage grouse.
Robinson said the latest finding of the hybrid was on a small sage grouse lek, but there were sharptail leks in the general vicinity.
Male sharptails and male sage grouse have distinctively different mating rituals.
Sage grouse have long, pointed tail feathers and large air sacs in their neck. The male sage grouse will stand stately, fanning out his tail feathers and inflating his airs sacks. When the air is released it creates a “booming” sound that attracts sage grouse hens that might be receptive.
Sharptail males tip their beaks forward to the ground while pointing their sharp tails up, and they cup their wings and dance in circles to entice hens.
In the case of the hybrid, Robinson said it was trying to do both.
Its tail isn’t quite that of the sage grouse so it wasn’t able to fan it out completely. And while the air sacks would puff up, they didn’t produce the booming sound.
So, Robinson said, the bird tried to dance like s sharptail, but it had some difficulty getting that just right.
“He was going back and forth between the two,” Robinson said.
Feathers were collected from the lek and have been sent to a Colorado lab for DNA analysis which will determine the bird’s lineage, he said.
Robinson suspects a male sharptail was the sire of the hybrid because they are more aggressive in the mating rituals than are their counterparts, sage grouse males.
Kohn also believes that is the case. Because the lek was small, with only three males, that may have provided a greater opportunity for a sharptail male to find a receptive sage grouse hen.
The sharptail population in that part of the state is doing well, so it’s a matter of numbers, he said.
With a small sage grouse population these days — fewer than 100 — and a healthy sharptail population coupled with a shrinking sage grouse habitat — some overlapping is bound to happen.
“The sage grouse are living on the edge of good habitat and at some point they will be milled about together,” Kohn said.
Sharptails and prairie chickens do interbreed but their habitats are more closely related to one another than are those of the sage grouse and sharptail, Kohn said.
As far as competition for habitat and food sources, there isn’t much between the sage grouse and the sharptail. But apparently there is competition when it comes to the availability of potential mates — and the availability of opportunity.
And this will add to the literature and data of what little is known about instances when the two species do come together.