posted on August 13, 2005 00:00
Friday, May 14, 2004
Reading The Landscape For Upland Birds
Andrew McKean, FWP Information Officer, Region 6
Last winter knocked the stuffing out of many residents of northeastern Montana—including the thousands of pheasants and native grouse that starved when deep snow covered food sources.
Now bird hunters want to know: This fall, will we have more or less birds to hunt compared to last fall? A lot of factors go into the answer.
Biologists know that if environmental conditions are right, winter’s losses can quickly become springtime’s abundance. That’s the nature of upland bird species that evolved so they would reproduce exponentially when habitat conditions are ideal.
Here is how biologists get a reading on how volatile bird populations may be doing.
The first factor is over-winter survival, according to Harold Wentland, regional wildlife manager in FWP’s Region 6. Springtime crowing counts for pheasants and lek, or breeding ground, surveys for grouse provide general trend data on surviving adult populations.
“We estimate that we lost about half of our adult grouse and pheasants last winter here in northeastern Montana,” Wentland said. “We had high numbers of adult birds last fall, so that doesn’t mean we lost everything, but the winter was severe and we are seeing some significant declines in the adult segment of the population.”
Biologists also look at spring nesting conditions.
“The key to nesting success is large blocks of cover such as sagebrush for birds, not just small clumps or islands of cover,” said Al Rosgaard, Havre area wildlife biologist. “Pheasants prefer taller cover that provides overhead protection. Sharptails get by with shorter cover, but do better in big blocks of dense nesting cover. Sage grouse prefer clumps of sagebrush and do better where there is good grass and forbs cover in the undergrowth.”
Nesting success also depends on spring precipitation. In much of eastern Montana, sage grouse start gathering on breeding grounds, or leks, in late March. Sharp-tailed grouse are close behind, and pheasants breed from mid April through early May.
Inclement spring weather can affect the breeding in April and May, but it’s not as critical as the weather is when hens are incubating or hatching eggs, Wentland said. Generally, a wet, warm spring is ideal for most upland birds species.
“If we get a deluge of cold rain, or a heavy, wet snow, the hens may abandon their nests,” he says. “The opposite is also true. We have documented that very hot weather can literally cook chicks in their eggs.”
Most critical to survival is the weather from the time the chicks hatch until they start to fledge, or grow feathers. Timely rains sprout new vegetation that birds need for food and hiding cover. Warm temperatures and thick vegetation coax out the insects that chicks need for high-protein food in their first few weeks of life.
So how does this spring’s weather look from the perspective of an upland bird? Pretty good, say biologists. Last winter’s deep snow in the northeastern portion of the state left enough moisture in the ground for good vegetation growth. Temperatures have been mild, and though a mid-May snowstorm covered much of northeastern Montana, if the snow melts and warm weather prevails, nesting success should be good. Conditions in other parts of the state may be much drier.
In the months ahead, that leaves localized hailstorms, flooding, predation, agricultural practices, diseases, range fires and a host of other potential events that may affect bird populations.
How will upland game birds fare this year? Let’s hope for a wet, warm spring. In the next column we’ll look at the summer months and the effect of agricultural practices on upland bird populations.
Editor’s Note: This is the first in a series of three stories looking at the factors that affect upland game bird numbers.