At 47° latitude and 3,000 ft elevation, winter has yet to turn the corner in Montana’s Mission Valley. While I’m envious of your reports of warming days and flowering fruit trees, I don’t mind slogging through another few weeks of cold, ice, and snow if it means enjoying the company of local wintering raptors.
Forgive me for prolonging your winter, but I didn’t think offering a photo diary of gorgeous raptors would be too tortuous for my Dawn Chorus comrades. This is my fifth winter in Mission Valley and I’ve gained a fair understanding of how raptors use this landscape. But each winter is different, and that insight is always getting upended. It’s humbling, but I’m here for it.
Ninepipes National Wildlife Refuge vicinity map. Ninepipes was named for an indigenous family that was displaced when an irrigation reservoir was constructed on their land in the early 1900s.
The focal area of this diary is Ninepipes National Wildlife Refuge, located in northwestern Montana on the Flathead Indian Reservation, with the spectacular, snow-capped Mission Mountains as backdrop. The refuge and surrounding state, tribal, and private lands make up an 18,000-acre sprawling complex of wetlands and grasslands managed as staging and breeding habitat for native birds, primarily waterfowl and waterbirds.
A kettle pond surrounded by grassland habitat on Ninepipes Refuge, with the Mission Mountains rising in the distance.
Ninepipes sits on a glacial terminal moraine left by receding glaciers some 11,000 years ago. Blocks of ice that were imbedded in outwash sediments slowly melted, leaving depressions that filled with water by precipitation and overland runoff. The resulting landscape is a prairie pockmarked with thousands of pothole wetlands and kettle ponds, connected by gently rolling grasslands.
Grassland raptors require large, contiguous tracts of open grasslands such as those provided by the Ninepipes complex.
Grassland cover types make up ~60% of the Ninepipes complex land base. A mix of grass species is maintained to seasonally benefit multiple wildlife species, with an emphasis on nesting waterfowl. In winter, however, the grasslands are the domain of raptors and thriving populations of rodents. Across my five years of observation, winter’s steadfast grassland raptors are Northern Harrier, Short-eared Owl, Rough-legged Hawk, and Prairie Falcon, with a few others making “guest” appearances.
Northern Harriers are long-winged and long-tailed, with a distinct white patch at the base of their tail.
Northern Harriers (NOHA) are probably the most common raptor of Ninepipes grasslands. These slender, agile Accipiters are often seen foraging on the wing, flying low over the ground, wings held slightly up in a “V” shape, often making cartwheel-like ambushes on their prey. NOHA’s disk-shaped face looks and functions much like an owl’s, with stiff “filo feathers” that funnel sound to their keen ears. The filo “disk” can be raised or lowered at will to home in on prey hiding in dense vegetation.
Northern Harrier juvenile male based on green-yellow eye color and cinnamon wash on its belly. [zoom]
I’m unsure if the NOHAs I see in winter are resident or migrants. I know there is some emigration of adult male NOHAs in winter, as they are rarely seen. I would hazard to guess that 95% of the NOHAs I see in winter are adult females or juveniles. Where do all the males go in winter?
Northern Harriers are sexually dimorphic, meaning males and females have distinctly different plumages. Males (pictured here) are gray above, whitish below with black wingtips. Females and immatures are brown, with black bands on the tail. [zoom]
Ninepipes is meadow vole heaven (unless you’re on the receiving end of those talons!). Meadow voles likely make up the bulk of NOHAs’ diet, though in years when small flocks of Snow Buntings and Horned Larks wander through, these songbirds would certainly be targeted.
Juvenile NOHA downs the last of a meadow vole. [zoom]
David Sibley describes NOHA as “generally solitary,” but I’m not sure that description fits in winter. At Ninepipes, I’ve observed a couple of early morning NOHA “fly-outs” from communal ground roosts (15 birds from one cattail patch). Communal roosting of NOHAs and Short-eared Owls is well documented across their winter ranges; I expect it also occurs in the Ninepipes grasslands. Occasionally, I’ll come across a group of 3 or 4 NOHAs engaged in impressive aerial scuffles. These usually involve a NOHA with a vole being harassed by others intending to pirate the prey item, a practice known as kleptoparasitism.
The chase is on to steal a vole in the possession of the NOHA in the lower right. [zoom]
A third NOHA joins the skirmish…. [zoom]
Short-eared Owls (SEOW) both winter and breed in the Ninepipes grasslands, and they are always a delight to see. Sibley calls them “essentially the nocturnal counterpart of the Northern Harrier.” My impression is that winter occurrence of SEOW changes each year, but I can only speculate as to why (snow depth? temperatures? prey abundance?). A cattail patch that held 20+ roosting SEOWs in December 2023 held zero owls a few weeks ago. In February 2021, I found a group of 30+ SEOWs group-hunting for voles during a winter storm (Dawn Chorus: A Winter Gathering of Owls). SEOW is known to be irruptive based on a 4-year cycle among tundra and grassland rodents. It’s possible this irruption dynamic occurs in Ninepipes, but a more basic explanation for annual population fluxes may be SEOW’s intrinsic sensitivity to local environmental conditions.
Short-eared Owl in dusk hunting mode. This was a private parcel under conservation easement. [zoom]
A Northern Harrier (far left) waiting to steal a vole from a Short-eared Owl. [zoom]
Rough-legged Hawks (RLHA) are strictly winter visitors to the Ninepipes grasslands. They arrive in early November and are probably departing to Arctic tundra breeding grounds as we speak. I am enthralled with this bird in its endless, absolutely gorgeous plumage patterns. I love their long-winged gracefulness, delicate beak and feet, and their shy wildness. It’s always a thrill to have one in my sights, and an even bigger thrill to have one in my camera viewfinder.
“Rough-legged” refers to the feathering that extends down the legs to the base of the toes — a helpful adaptation for staying warm in frigid climates. [zoom]
I usually see them perched on power poles, wheel lines, fence posts, or trees where they hunt by sight for voles and other rodents.
Determining age and sex of RLHA can be tricky without seeing the bird in flight. [zoom]
The blurry subterminal tail band, pale head, and dark belly make me think juvenile (1st year). [zoom]
Poor focus on this beautiful RLHA, but photo shows leg feathering down to its feet.
RLHAs have small feet, enabling them to perch on small branches. [zoom]
Of course, they’re also spotted soaring or hovering over grassland habitats. These in-flight observations are my favorites, as they reveal the unique and striking patterning of the undersides.
A light morph juvenile (1st year) RLHA
Another light morph juvenile missing a few flight feathers.
Guessing a light morph adult female based on pale breast, dark belly, distinct tail band, and underside of primaries being clean white. [zoom]
Montana ornithologists have documented RLHA communal winter roosts along the base of the Mission Mountains holding up to 200 birds. This past year, I noted a very loose communal roost of ~50 RLHA and Red-tailed Hawks in a Douglas-fir/cottonwood riparian forest bordering Ninepipes Refuge. This very well may be one of the earlier documented winter roosts, but it was still a thrill to see so many hawks bee-lining to this copse of forest at last light.
Prairie Falcons (PRFA) may be year-round residents of the Ninepipes complex or possibly short-distance migrants. In winter, they number few, but are consistently seen year to year. The PRFA’s entire mode of hunting is adapted to grasslands, and they use a variety of hunting techniques including the well-known “stoop” and mid-air blow; a fast, low-to-ground cruising tactic; and line-of-sight ambush from high perches. Their winter diet consists of small rodents and the occasional Horned Lark or Snow Bunting. I would wager they make a small dent in the local Red-winged Blackbird population as well.
Adult Prairie Falcon waiting out a freezing, foggy morning.
Adult Prairie Falcon bloodied by its prey item.
Besides the four grassland specialists highlighted, the Ninepipes complex also hosts a few other raptors that are more “generalists” or make quick stopovers during migration.
Great Horned Owls readily nest in mature cottonwoods growing in old homestead sites. [zoom in]
Red-tailed Hawks are common throughout the farm and ranch lands of the Mission Valley.
Red-tailed Hawk circling overhead. [zoom]
Merlins are small, scrappy, and lightning-fast falcons that specialize on small to medium-sized bird prey. I believe this was a juvenile Merlin of the Taiga population, which winters continent-wide. [zoom]
Female American Kestrel floofed out to trap body heat on a bone-chilling morning. [zoom]
Bald Eagles are quite common in winter; favorite haunts are ranches during January/February calving where they feast on cow afterbirth. [zoom]
Common Ravens seem to make good sport of harassing this Baldy. [zoom]
Thanks for dropping by,
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