Jan 13, 2016

Wyoming's sage grouse producing more chicks, Game and Fish says

It’s great news for greater sage grouse.

There were more greater sage grouse chicks born in 2014 and 2015 in Wyoming than in previous years, according to the Wyoming Game and Fish Department.

The number of sage grouse chicks (like the one pictured above) has risen in the past two years. File photo courtesy U.S. Fish and Wildlife Service
There were 1.7 chicks per hen in 2015, the same count as 2014. That ratio is the highest the department has documented since 2005, and more than double the recent low of 0.8 chicks per hen noted in 2012.

The 10-year average, from 2005-14, was 1.3 chicks per hen. Grouse numbers declined in most of those years, according to Game and Fish.

The new data on the Wyoming sage grouse population — based on an analysis of greater sage grouse wings provided by hunters — indicate that bird numbers should continue to grow in the coming year, the department says.

The Game and Fish says hunters contribute to sage grouse management by voluntarily dropping wings from the birds they harvest into barrels scattered across central and southwest Wyoming.

“Wings tell us chick production,” explained Tom Christiansen, Game and Fish sage grouse program coordinator.

Wings can indicate if the hen produced broods based on the progression of molting — the shedding of old feathers to grow new ones.

Hens that molt slowly have had chicks while faster molting indicates hens did not brood, Christiansen said.

The amount of old feathers that a sage grouse hen has shed from her wings indicates whether she produced a brood that year.

“We don’t collect wings in the Big Horn Basin,” Christiansen said.

There are only about 200 sage grouse killed across the entire Basin in an average season, so it would be too time consuming to distribute barrels over the wide area for the limited amount of information it would provide, Christiansen said.

Generally favorable moisture patterns this past spring and summer provided better than average conditions for chick survival. During their first month of life, newly hatched sage grouse chicks rely on a high protein diet provided by insects. Spring and summer rain lead to increased grass and wildflower production, which in turn leads to more insects available for young birds.

It’s a delicate balance of precipitation and temperature that impact chick survival.

Too much cold and wet, or snow, and chicks will die of exposure. But, if it is too dry, insects and forbs will be scarce in the critical time when chicks need nutrition to survive. The right balance of spring and summer precipitation ensures chicks will have plenty of insects, Christiansen said.


GROUSE FACTS

If hens lose their chicks to weather or a predator, they won't hatch another brood that season. However, if they lose their young while they're still eggs, a hen will revisit a lek (sage grouse breeding ground) to reproduce with a male again, Christiansen said.

That’s why the breeding season runs from March to late May. In April, there will be two to three times as many females as males, so females have the opportunity to breed with males. By mid-April to May only two or three hens will visit leks, Christiansen said.

Grouse grow fairly quickly: by September, a male chick will be larger than his mother, he said.

Unlike many species of wildlife, sage grouse put on weight over the winter by eating sagebrush leaves, as long as the shrub is not covered in snow. Beefing up in the colder months helps put males are at their peak when the spring strut starts, Christiansen said.

“Sage grouse like winter,” he said.

The population rises and falls based on a seven- to 10-year population cycle. So Game and Fish has to look at long-term trends to see how the population is faring, Christiansen said.

Still, having a good chick year is encouraging.

“Certainly we needed the increase now, and it’s welcome news,” Christiansen said, adding, “It is good to see that sage grouse numbers are still climbing. We know populations are cyclical, and we are in a wet period that benefits sage grouse and their habitat.”

He said the department appreciates the sage grouse hunters who opt to donate their birds' wings, saying their participation and the data from the wings helps with the grouse's management.

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