Glacier Swift

 

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Glacier Swift, Cypseloides glacialis L 15 cm, WS 35-45 cm, Family: Apodidae

 

IUCN Status: Critically Endangered (CR)

 

Description:    

Field Guide Reference

Large, active swift with cigar-shaped body and long, curved, tapered wings. Squared tail. Dark sooty gray overall, with darker black feathers on the belly and a slightly lighter throat. Bill and feet tiny. Sexes similar. Almost never observed perched, flight is generally acrobatic and incredibly fast.

Voice:

Frequently vocalizes with high-pitched and rapid chips and twitters.

Range and Habitat:    

Summer range encompasses high-elevation portions of the Paramount range and areas in the island’s far north. Migrates to spend winter in South America. Breeds exclusively near glaciers and cliff faces, and forages in surrounding alpine or coastal areas. Extremely rare, only 13 breeding sites are known.     

Discussion:      

Glacier Swifts have one of the most unique nesting strategies of Novasolan endemic birds. As the name suggests, Glacier Swifts almost exclusively build their nests within cracks and crevices of glaciers and are one of only a few bird species in the world to do so. Birds will find small depressions or shelves in the ice walls of the glacier upon which they build their nests, which are shallow mats of moss, lichen, and mud. Swifts may carve spaces into the ice for the nest. Some nests may be built deep within dark or inaccessible crevasses. Glacier Swifts nest in loose colonies, where many birds will nest within a particular section of glacier. These colonies will return year after year to nest in the same glacier, albeit not in the same spots given how glaciers move and change. Swifts presumably form monogamous pairs and both parents take turns incubating the egg while the other forages, though this has not been confirmed. Each female lays only a single egg. It is unknown whether fledged chicks return to the same colonies in subsequent years or disperse to join new ones. Not all Glacier Swifts nest within glaciers, however. Of the currently active breeding sites, two of them are not in glaciers but are instead large cliff faces. Birds in these colonies form similar nest mats but do so within cracks in the cliff. It is unclear whether this has always been the case or whether cliff nesting is a more recent adaptation to climate change and disappearing glaciers.

Except when nesting and incubating, Glacier Swifts almost never leave the air. They have a remarkable ability to stay airborne for weeks at a time. They eat, drink, copulate, and outside the nesting season even sleep on the wing, which they achieve by only shutting down parts of their brain at a time. When they do occasionally land, usually to roost, they do so by clinging to vertical surfaces like ledges, cliffs, ice walls, and large trees. They almost look more like bats than other birds in this way. Swifts exclusively eat flying insects like flies and winged ants, which they catch midair. They are most active at dawn and dusk but may be seen at any hour of the day. Swifts can fly at surprising altitudes and may spend much of the day foraging well above most other birds.

Social birds, Glacier Swifts are often seen in small to large flocks. These flocks generally forage, roost, nest, and migrate together. Swifts breed on Novasola in a short season in the summer and migrate huge distances to spend the winter in parts of South America, presumably. No flocks of Glacier Swifts have been found during winter, so exactly where they migrate to is still unknown, but it is thought they winter in inaccessible mountainous parts of Peru, Ecuador, Columbia, or Venezuela. Swifts will migrate in large flocks which are likely made of multiple breeding colonies and may include other species like swallows or other swifts.

Glacier Swifts are one of the rarest birds on Novasola and are considered critically endangered. They were most likely always a rare species, given their habitat and breeding specialization, but have seen devastating population crashes over the past century. These declines are directly related to the shrinking and disappearing of glaciers across Novasola due to climate change. Novasola’s high-altitude peaks and northern fjordlands once hosted thousands of glaciers, but now fewer than one hundred remain, mostly limited to portions of the Uludaqs, Steller Range, and the north coast. No glaciers, and thus no swifts, can now be found in either the Angelic or Morning mountain chains, where once there were many. Considering their inaccessible breeding habitat and low numbers, very little is known about Glacier Swifts. They are one of the least-studied birds in North America, let alone Novasola. There isn’t even a consensus on the total population of the species, with estimates ranging from a few hundred to close to 500,000. It is most likely that fewer than 6,000 individuals are left, and only 13 confirmed nesting sites are known. Of these, 11 sites are within glaciers and two are cliffside colonies. The glacier colonies are dispersed widely across the Paramounts and north coast, and the two cliff colonies are both located north of Great Shadow Lake. To help protect the remaining sites, exact locations for all but one of the breeding sites are kept secret from the public to prevent tourist-related disturbance. The only publicly disclosed nesting site is in the Angeles Glacier within Mt. Atlas National Park, where a colony of around 200 birds reliably nests every year. For most people, this is the best place to observe Glacier Swifts during the breeding season when they leave from cracks in the ice en masse each dawn and return at dusk. Otherwise it is extremely difficult to find the birds except during migration. Scientists are currently working to learn as much about the species as possible before they go extinct, which unfortunately seems inevitable. Every year researchers and volunteers systematically search Novasola’s mountains and fjords hoping to find new nesting colonies, while others monitor known sites to get better population estimates and hatch rates. Unfortunately, accessing nest colonies is difficult if not dangerous or impossible, so there are still many unknowns. In the past few years some scientists have begun looking into finding ways to attach GPS transmitters to swifts to locate their wintering grounds. The hope is that the swift’s wintering habitat may be easier to protect or conserve than their breeding habitat, as there is little that can be done to prevent the further melting of glaciers without fundamental global shifts in industrial practices and climate change attitude.

 

Even though they are far rarer now than in the early 1900s, Glacier Swifts had already begun to decline by the time of the NRC expeditions. Richard Reichwald was the first to describe the species for science during the third NRC expedition but only observed the birds on one occasion. It wasn’t until mountaineering and glacial exploration on Novasola took off in popularity decades later that the first nest was found.

 

“For two days as we cross the Sasan we have seen little of life within this desolate landscape, save the few birds flying high overhead. Swifts abound in the skies above the glacier. The birds flit so high in the blue that they appear as mere dots, exceedingly difficult for my eyes to track, and they are made known mostly by the chattering calls that grace my ears during moments of quiet stillness when our gear settles.” – Expedition log, August 16, 1903

Typical Glacier Swift nest. Simple moss nests are typically placed on a vertical ice wall inside a glacial crevasse. Illustration provide by the Museum of Novasola.