Idaho’s complex topography has been sculpted over millions of years by sediment deposition, volcanism, thrust faults, glaciation, and erosion — even a giant meteorite. The legacy of these forces shaped a landscape with an abundance of cliffs, bluffs, and rocky outcrops used as breeding habitat by a diverse array of birds. Arguably, one of the finest places to view these spectacular landforms and their cliff-nesting denizens is the Upper Salmon River in east-central Idaho.
I was fortunate to spend 16 years as a wildlife biologist in the Upper Salmon, in part monitoring peregrine falcon and bald eagle nests along its 170 miles of rugged river canyon. In my rounds, I observed ~20 bird species using “hard rock” habitats for nesting, foraging, retreat sites from predators, and vantage points to hunt and defend territories.
Jump on in and let’s take a virtual float trip downriver to chase some cliff nesters. What better way to spend a hot summer day?
A small black and white bird with long saber-shaped wings, the white-throated swift is perfectly designed for life among the cliffs. This “little torpedo” spends most of its time on the wing hurtling along canyon bluffs in search of flying insects. One of their most spectacular behaviors is their aerial courtship display in which a pair mates while tumbling earthward, sometimes for over 500 feet! They construct nests made of feathers glued together with saliva deep within rock crevices. Because they nest in small colonies beyond the reach of human observers, little is known of their breeding biology. In their search for aerial insects, they often follow thermals high above the cliffs where they can be difficult to observe. Listening for their distinct call — a shrill, chattering “je-je-je-je” in descending scale — will tip you off to their location.
Swallows
One of the most conspicuous and abundant of cliff/rock nesters is the cliff swallow. A colonial nester, cliff swallows build their spherical nests of mud pellets high on sheer cliff walls. The nests are lined with grass and feathers for warmth and are nearly fully enclosed to protect nestlings from wind and rain. Hundreds of these mud nests can crowd a cliff face, almost appearing like part of the rock substrate itself. Living in close quarters benefits the sharing of food resources and the detection of approaching predators.
More often known as tree cavity nesters, violet-green and tree swallows occasionally nest in small, loose colonies in cliff crevices, lining their rocky niche with grass and feathers.
Barn swallows also utilize cliff crevices and caves as substrate to support their cup-shaped nests of mud pellets, straw, and feathers (they nested somewhere before there were barns!).
Two additional species, the bank swallow and northern rough-winged swallow, also nest in the vicinity, usually in excavated or abandoned burrows in streambanks or roadcuts.
From May to late August, the Salmon River Canyon swarms with swallow activity, offering great opportunity to see courtship flights, aerial foraging on the plentiful insect life, feeding and fledging of young, and the chance to see thousands of swallows perched on wires and fences during a summer thunderstorm.
Canyon Wren / Rock Wren
Two species of wren, the canyon wren and rock wren, occur in the Salmon River Canyon. Canyon wrens are found among cliffs, rocky outcrops, and steep-sided canyons where they build nests protected by a protruding ledge or rock shelf. The base of their cup-shaped nest is made of twigs and grasses, then lined with lichens, plant down, wool, cobwebs, or feathers. The canyon wren diet consists of insects and spiders, which they probe from rocky surfaces with the aid of their flattened cranium and long slender bill. Though somewhat humble in appearance, there is nothing ordinary about this bird’s loud melodious song described as a “cascading series of liquid tee’s and tew’s that decelerate and descend” down the canyon.
Rock wrens are found in rock-strewn areas such as talus slopes and rock piles. Like the canyon wren, their nests are built in rock crevices among boulders and other sheltered sites. Curiously, they pave the entrance to their rock-sheltered nest with small stone chips, the purpose not fully understood. Their diet also consists of insects and spiders gleaned from crevices by their long bill. Rock wrens display a characteristic “bobbing” behavior as they flit from rock to rock, fanning their broad buff-tipped tail as they land. During breeding season, the male is a virtuoso performer, rivaling the mockingbird with its large repertoire of songs with buzzy, trilled, and ringing phrases.
American Dipper
Another interesting resident of the river canyon is the American dipper (aka water ouzel), a small songbird uniquely adapted to cold mountain streams, where it dives to forage on aquatic insects. Adaptations for the life aquatic include nasal flaps to prevent water from entering its nostrils, a thick layer of insulating down feathers, a large preen gland to maintain waterproof feathers, and specialized vision that corrects for refraction in water. Dome-like nests are built on streamside rock cliffs or on large rocks midstream. Nest materials include an inner cup-like lining of dry coarse grass with an outer shell of moss and interwoven grass. Viewing these stocky, solid gray birds can be challenging because of their small size, cryptic coloring, and scarcity during hot weather (they are very intolerant of heat).Training a keen eye along streambanks for their distinct “dipping” movement will help in detecting these birds, as will a trained ear listening for the male’s bubbling, wren-like song sung LOUD to be heard over rushing water.
Common Raven
North America’s largest passerine, the common raven, readily nests in large alcoves, large fractures in cliff walls, or in protected, well-shaded ledges along the Salmon River Canyon. Their large bulky nests are usually built of stout sticks lined with grass, fur, bark, or whatever treasure caught the raven’s eye. Ravens are quite secretive when incubating and tending to young. The most successful strategy for viewing nesting ravens is to scan cliff faces for evidence of fresh “whitewash” (bird excrement) and presence of stick nests. Their hoarse, croaking vocalizations can also tip you off to their location.
Peregrine Falcon
If there is a bird that embodies the rugged grandeur of the Salmon River Canyon, it’s the peregrine falcon. The canyon supports several breeding pairs, distinguishing this river reach as one of the highest-density peregrine breeding sites in Idaho. The return of a breeding pair to their territory in early April is marked by courtship rituals including spectacular aerial displays, courtship feeding, and endless calling. Nest sites, or eyries, are selected by the female on high, vertical cliffs near water and a plentiful supply of avian prey. Peregrines do not build nests per se, but scrape a shallow round depression in the soil in which they lay 3-4 eggs. Peregrine adults become very quiet and secretive during incubation and early brood rearing, but increase their activity as chicks require feeding up to 10 times per day. At about six weeks of age the chicks are running laps along the eyrie ledge and endlessly flapping wings in preparation for their maiden flight.
Other Birds of Prey
The Salmon River Canyon provides ideal breeding habitat for raptors. Strong thermals are used for effortless flight; cliff ledges provide remote and secure locations for nesting; and rabbits, marmots, ground squirrels, and other small mammal prey are abundant. Red-tailed hawks build robust stick nests in high sheltered alcoves on cliffs. Golden eagles are rare nesters in the Salmon River Canyon, but select nest sites similar to those preferred by red-tailed hawks. Great horned owls are occasionally seen occupying abandoned stick nests of ravens or hawks. American kestrels commonly nest in small rock cavities and crevices. The uncommon prairie falcon nests in potholes on shear rock ledges, preferring nest sites protected from the midday sun and situated about 50 ft. from the base of the cliff.
Whether by land or by boat, from a distance or neck-craning close, the cliff/rock landforms of the Salmon River Canyon - and the birdlife they support – are a must-see for those that appreciate breathtaking scenery and the genius of bird adaptations.
Your turn, feathery friends!
please share anything of avian interest happening in your part of the world!
And finally, a bird-themed proverb to help us get through another week of political chaos:
If you keep a green bough in your heart, then the singing bird will come.