by Kat Peterson

Black Swift

I sat and watched a single dark bird emerge from behind a fall of water that trickled down the base of this jagged peak which had formed and since been carved by glaciers. I took a moment to recollect how exactly I had traveled to this remote destination to peer upon this relentless yet breathtaking scene; catching fleeting glances of the little speck of a swift sweeping above this alpine lake. The day began backpacking 6 miles into the Cabinet Wilderness, passing waterfalls and grand views of craggy peaked horizons along the trail. Once I arrived at the pristine, glacial fed waters of Granite Lake, I began blowing up a pack raft I had hauled in to continue to my destination. Just as my raft, backpack and myself kissed the edge of the lake, a black bear cub appeared upon the edge of the treeline, and I felt a sense of relief to be sailing the water. After a mile of paddling against harsh winds at 4,700 feet, the tumbling waterfall came into view, and I knew this was the Black Swift’s nest site I had sought.

The Black Swift (Cypseloides niger) is a wondrously elusive passerine with incredibly unusual nest habits and much mystery still surrounding it.  Their graphite bodies have contrasting upper and lower wing coloration. They fly with crescent moon shaped wings and a long squared-tipped tail. Males have a distinct notch in their tail while juveniles’ plumage have small bands of white present across much of the underbody. Being the largest swift in North America, Black Swifts trump our other local Vaux’s Swifts in overall stature, and tail length. Their wingbeats are shallower with a less erratic flight pattern than other swifts.

Black swifts fly at an incredible height and speed to forage for winged ants and other insects. You can often spy a Black Swift flying in the clouds with their mouth open hunting insects in rising air masses that sweep large quantities of bugs into the sky. In summer Black Swifts migrate to Montana to nest and come fall they return to South America. Although the exact whereabouts of Montana’s Black Swifts wintering habitat remains a mystery, other studies of GPS equipped swifts found they migrate to lowland rainforests in Brazil.

Black Swifts’ breeding grounds are spectacularly unique. They greet Northwest Montana to build nests in the most incredible and harsh terrain our mountains have to offer: high elevation waterfalls. The birds require veryparticular waterfall characteristics suitable to build their nests upon shady, sheltered crevices or overhangs beneath the falls. These waterfall requirements include height and structure, water volume, view over terrain, moss availability, shading of nest niches, aspect, elevation, and even rock type. Breeding pairs have strong nest fidelity returning to previous years cup nest built of moss and mud. Before 1961, Black Swifts were only documented in Montana by fleeting observations. However, that year wildlife researchers Hunter and Baldwin conducted the first established study where they observed 5 active nest sites in the Mission Mountains.It wasn’t until2004 when Dan Casey, then regional coordinator for Northern Rocky Mountain Bird Conservation, reignited interest in Black Swift ecology by assembling a team to search for active nest sites. Ten years later in 2014, researchers and volunteers began the current Black Swift research project resulting in 7 occupied waterfalls. Since 2014 collaborative survey efforts from Glacier National Park aided by wildlife biologist Lisa Bate, MT Fish, Wildlife, and Parks, and Montana Audubon have resulted in yearly surveys seeking out new nest sites and monitoring established ones. The 2021 field season reported 51 active nest sites, and 13 annually monitored nests.

Although information on Montana populations is quite limited, North American populations have declined 90% since the 1970s. They are a species of conservation concern in Montana, however because we have limited understandings of their winter locations, and overall ecology, the reasons for their population decline are not certain. The fate of these birds is inevitably linked to water, and climate change makes them vulnerable to extirpation. With the onset of greater droughts and warmer weather conditions, glacial fed waterfalls may experience decreased waterflow. Furthermore, Black Swifts are highly specialized feeders, and declines in arthropods (their main food source) due to environmental changes such as drought directly affect them as well. Perhaps this drastic decline can also be contributed to their brood size: they only lay one egg per clutch each breeding season and will not re-nest if their initial clutch fails. The good news for Montanan Black Swifts is they have been observed collecting mosses from outside their nest waterfalls, which may luckily indicate they have some resilience to the changing moss availability as droughts become more frequent. Also, the 13 regularly monitored nests have shown to be consistently productive.

In the summer months the best place to view these acrobatic birds flying among the clouds is near water sources that create the breathtaking falls they nest upon. Some popular summer hiking locations include Morrel Falls in the Swans Mountains, Holland Falls and Avalanche Falls in Glacier National Park, and Granite Lake in the Cabinet Wilderness.

Interested in learning more about and catching a glimpse of these avian enigmas?  Contact Amy Seaman to learn more!