After miles of watching center pivots and transmission lines and scanning treetops with binoculars, Ross Winton and Amaia Demaray had spotted only one eagle, flying away from a swan-filled pond on Clover Creek.
Their Jan. 13 drive along the Bennett Hills foothills north of Bliss was an annual survey of bald and golden eagle numbers — one of nine eagle-counting routes between Raft River and Bruneau that contribute to the U.S. Geological Survey’s national monitoring of bald eagle populations.
I joined Winton and Demaray that day, a frigid morning when fields were frozen lakes, with crop stubble propping up ice sheets at strange angles. Population science, I figured, was an excellent reason to get out of the newsroom for a few hours.
Removed from the federal list of threatened and endangered species in 2007, the bald eagle now flourishes across the nation thanks to the banning of the pesticide DDT and the protection of nest, feeding and roost sites, the U.S. Fish and Wildlife Service says.
Idaho’s bald eagle population has generally risen since the 1980s — but with big spikes and drops in various areas, said Winton, a Jerome-based regional nongame wildlife biologist for the Idaho Department of Fish and Game.
The Bliss-to-King Hill route he drove Jan. 13 yielded 29 bald eagles in 2015 but just one a year ago — perhaps because good fish runs in northern Idaho drew the eagles there instead. And milder winters might boost recorded numbers just because survey teams can get around better on rural roads.
As always, Winton added, interpreting the behavior of wildlife populations calls for humility.
“We don’t know half of why they do what they do.”
Still, he seemed eager to record more than one eagle on wildlife technician Demaray’s clipboard.
Not too eager, however, to stop for a better look at about 50 swans in one of the White Arrow Ranch ponds.
After noting the lone eagle’s flight, Winton fastened a scope to the open window of his Fish and Game truck and focused on the honking crowd.
“I see lipstick,” he said. But did that bill marking identify the trumpeter or another Idaho native, the tundra swan? “One has a teardrop and one has lipstick, and I never can remember which is which.”
The “Sibley Guide to Birds,” kept handy on the floor between us, settled the matter.
“Trumpeters,” Winton announced. “There’s a bunch of juveniles in there, too.”
Nice, of course, but not the goal of this survey.
As we headed west along Clover Creek, I tried to contribute by pointing out a couple of big lumps in a distant tree. Winton and Demaray turned their binoculars there and, kindly, identified the lumps: a magpie and a pheasant.
Moments later, the truck’s approach flushed a lot of pheasants and sage grouse. Another treat, but still not bald eagles.
Northwest of Bliss, Winton turned west onto 1200 South, approaching a Clover Creek crossing and a big tree with a well-earned reputation. And it delivered. Six eagles roosted in its branches, and another flew off as the three of us got out with the binoculars, the scope and the clipboard.
Five adults and two juveniles, the team concluded.
“The Eagle Tree has worked again,” Winton said.
(Yes, that name is attached to more than one Magic Valley tree.)
As we approached Pioneer Reservoir, Winton explained that open water there can attract a lot of waterfowl — and, thus, the eagles that prey on them. But it’s shallow and freezes easily.
Indeed, we found Pioneer Reservoir frozen.
“There are a lot of geese flying all over the place, though,” Winton said. But no eagles. “Nobody’s home.”
Surveyors often find golden eagles roosting on hillsides beside Old U.S. 30, he told Demaray as we drove past them, so watch for the silhouettes. But those hills and other typical roosts on the route also came up empty. By the time they reached King Hill, only a line of more “Eagle Trees” had added to their count.
The day’s tally: nine adult bald eagles and five juveniles. Just about the midpoint of the range of recent years’ totals.
Winton has other interesting tasks on his schedule this winter: keeping tabs on the distribution of pygmy rabbits — a species that has been petitioned for Endangered Species Act protection — swabbing the muzzles and wings of hibernating bats to check for the fungus that causes the devastating and rapidly spreading white-nose syndrome, and mist netting cave entrances at dusk as bats become active in late winter.
I just might find another excuse to get out of the office.