Upland birds.

If they’ve been at it long enough to break in their boots, you won’t find many upland bird hunters who don’t marvel at the survival instincts of pheasants, grouse, woodcock and quail. But as remarkable as those instincts are, they may fall short when the new predator in the field is global warming.

“Birds are resilient and highly adaptable,” says Dave Nomsen, vice president of Pheasants Forever, “but when the food base is unstable and the protective vegetative covers are inadequate or unavailable, when there’s no moisture during the brood-rearing period, you’ve got trouble. When those conditions become the norm, you’ve got a disaster.”

If temperatures rise as much as experts forecast, up to 10 degrees Fahrenheit by 2099, and suitable habitat becomes scarce, upland bird populations are expected to collapse.

“We’ve already seen northern bobwhite quail populations decline precipitously over the last half-century,” says Kim N. Price, editor of Covey Rise and a member of the board of directors of Pheasants Forever. “Loss of successional habitat is severe. Compound this with the various factors related to climate change — additional losses of water, ground cover and food — and a serious situation becomes critical. We face a future where population losses of unseen proportions could make some upland bird species extinct.”

Recent analyses of American birds show that their breeding ranges are shifting northward, coincidental with a period of rising global temperatures. This change is occurring even though, worldwide, temperatures have increased on average only about one degree Fahrenheit during the past century.

While a 30 percent loss in the number of bird species is the worst case scenario, even conservative projections say that climate change is likely to alter the makeup of entire ecosystems, forcing wildlife to adapt or perish. Scientists’ concerns include the following:

• Across central North America, including the prairie pothole region, global warming will cause droughts that could devastate food sources for upland birds. Prairie chickens, sharp-tailed grouse and pheasants will be among the species most diminished in number by these changes.

• In the popular upland bird-hunting areas of the Great Plains and throughout the Midwest, the threat of long-term drier conditions and much warmer summer temperatures will decrease the nesting successes and recruitment rates of pheasants, grouse and prairie chickens.

• Higher temperatures will foster conditions favorable to invasive species such as the fire ant. Already  Texas and Oklahoma the problem of fire ants is increasing and puts hatchling quail at particular risk.

• In the Deep South, summertime drought and high temperatures will shrink bobwhite quail populations by disrupting the birds’ breeding cycles and reducing availability of the insects that hens and chicks eat. Hot, dry conditions will also stunt the growth of vegetative cover, leaving broods vulnerable to predators.

• In the desert Southwest and the high desert valleys of California and Nevada, drier and hotter conditions throughout late fall and early spring will imperil the overall health, reproduction and recruitment of quail and chukar.