The White-throated Swift (Aeronautes saxatalis) and the Black Swift (Cypseloides niger) are two similar-looking bird species that belong to the swift family Apodidae. Though they appear similar at first glance, there are several key differences between these two types of swifts in terms of physical characteristics, habitat and range, diet, and behavior.
In this article, we will provide a thorough comparison of the White-throated Swift and the Black Swift, looking at taxonomy, physical description, geographic range and habitat, diet and feeding, reproduction and nesting, and unique behaviors. Understanding the similarities and differences between these two swift species can help with proper identification and appreciation of their diversity.
Taxonomy and Classification
The White-throated Swift and the Black Swift are both members of the Apodidae family, which consists of over 100 species of swifts and hummingbirds.
White-throated Swift
The White-throated Swift is in the genus Aeronautes, which includes two other similar swift species – the White-naped Swift and the White-collared Swift. The species name saxatalis refers to its cliff-nesting habits.
Black Swift
The Black Swift is the only member of its genus Cypseloides. Its species name niger simply refers to its all black plumage.
Both birds are in the same subfamily, Apodinae, along with other American swifts. And they both belong to the order Apodiformes, which consists of swifts, treeswifts, and hummingbirds.
Physical Description and Markings
The White-throated and Black Swifts share some physical similarities being all dark birds with long swept-back wings. But there are also clear visual differences between them.
Size and Shape
– The White-throated Swift is larger, measuring 15-17.5 cm (5.9-6.9 in) in length with a wingspan of around 38 cm (15 in).
– The Black Swift is smaller at 12.5-15 cm (4.9-5.9 in) long with a slightly shorter wingspan of around 33 cm (13 in).
– Both have very slender, cigar-shaped bodies ideal for fast flight.
Plumage
– The White-throated Swift is dark brownish-gray overall with a contrasting white patch on the chin and upper throat.
– The Black Swift is, as its name suggests, entirely blackish with no pale throat patch. Its wings and tail may sometimes appear flecked with white.
– The Black Swift has a darker black coloration compared to the medium gray-brown of the White-throated.
Facial Features
– The White-throated Swift has a small black bill and beady black eyes.
– The Black Swift has a tiny black bill and slightly larger black eyes.
– Both species lack feathering on their faces.
Legs and feet
– They have very short legs that are feathered and the feet are small.
– The White-throated Swift has gray legs/feet.
– The Black Swift has darker blackish legs/feet.
Geographic Range and Habitat
The ranges and breeding habitats of these two swifts also differ:
White-throated Swift
– Found along the Pacific Coast of western North America.
– Breeds inland in mountainous areas from British Columbia south to Baja California.
– Nests colonially on vertical cliff faces and canyons.
– Forages widely over many habitats including forests, valleys, and towns.
– Migrates south to western Mexico in winter.
Black Swift
– Occurs along the Pacific Coast from southeast Alaska to northern California.
– Breeds very locally in mountain ranges near the coast.
– Nests solitarily or in small groups behind or beside waterfalls.
– Forages aerially over mountain forests and coastal waters.
– Migrates south to central Mexico and northern Central America in winter.
So while both are mountain-dwelling Pacific coastal birds, the White-throated has a more southerly range and breeds more commonly inland. The Black Swift sticks closer to the coastline and northern latitudes.
Diet and Feeding
The diets of these two swifts consist mainly of insects captured in flight:
White-throated Swift
– Feeds mostly on winged ants and termites.
– Also eats varieties of flies, beetles, bees, wasps, and other flying insects.
– Catches insects in sustained flight at heights up to 300 m (1,000 ft).
– Drinks by skimming low over water and gulping.
Black Swift
– Feeds predominately on emergent aquatic insects like mayflies, caddisflies, and midges.
– Also preys on various flying insects across habitats.
– Forages at heights up to 600 m (2,000 ft) over oceans, lakes, forests.
– Drinks by flying through waterfalls and mountain mists.
So while both are aerial insectivores, the Black Swift is more associated with water and high elevations, while the White-throated feeds more generally on land insects.
Reproduction and Nesting
The White-throated and Black Swift have some similarities and differences when it comes to their breeding habits:
Nest Sites
– White-throated Swift nests colonially on vertical cliffs and canyon walls with crannies and ledges for nest placement.
– Black Swift nests solitarily or in small groups, placing nests behind or beside waterfalls on cliffs and rock walls.
Nest Construction
– Both species build simple shallow nests out of twigs, pine needles, and feathers glued together with saliva.
– The White-throated Swift attaches its nest to rock crevices or ledges.
– The Black Swift fixes its nest to wet rock surfaces using waterfall mist and spray.
Eggs and Incubation
– They lay 2-6 white eggs that are incubated for 18-27 days.
– The White-throated Swift possibly has multiple brooding cycles.
– The Black Swift likely has just one brood per season.
– Incubation and brooding duties are shared by both parents.
So their cliff-nesting habits are similar but the White-throated is more colonial while the Black is more solitary. Their nest attachment methods also differ based on the nest sites.
Behavior and Adaptations
Some interesting behavioral notes and adaptations of these species include:
White-throated Swift
– Has very rapid and maneuverable flight for catching insects midair and even mate on the wing.
– Roosts communally at night wedged into crevices on cliffs and canyons.
– Lays flat against surfaces when roosting which minimizes its profile.
– Has the ability to go into torpor, lowering its body temperature and metabolism to conserve energy.
Black Swift
– Spends majority of its life flying, even eating and sleeping on the wing. Only stopping to nest.
– Has specially designed short legs and small feet to minimize drag in flight.
– Has large wing-surface to body-weight ratio enabling extremely swift flight.
– Has unique bristles around its mouth and enlarged lower eyelid that may help catch insects.
So the White-throated shows some energy-saving adaptations while the Black Swift demonstrates incredible aerial adaptations.
Conclusion
In summary, while the White-throated and Black Swifts appear similar as dark fast-flying birds, they can be distinguished by their:
– Size differences – White-throated larger
– Plumage patterns – White-throated has pale throat
– Geographic breeding ranges – White-throated more inland and southerly
– Cliff nesting habits – White-throated is colonial, Black is solitary
– Dietary preferences – Black feeds more over water
– Roosting behaviors – White-throated can go into torpor
– Adaptations for speed – Black has modifications for swift flight
These swifts represent a classic case of convergent evolution where distantly related species evolve similar morphological traits to occupy comparable ecological niches. Though superficially alike, a closer look at the White-throated Swift and Black Swift reveals some striking differences in accordance with their behaviors and habitat preferences. Their unique designs reflect the diversity of the Apodidae family.