Cave Swallow

As recently as the 1960s, the Cave Swallow was a rare bird in the United States. It nested only in a few southwestern caves, plastering its cuplike mud nest against the walls in the dimly lit interior. Since then, it has “learned” to nest in artificial sites, in culverts, and under bridges, and it has become a common summer bird across much of Texas and southern New Mexico. Even in Florida, it has become an outlying bird in recent years. In some places, Cave Swallows may actively compete with Cliff Swallows for these artificial nest sites.

About Cave Swallows

Cave Swallows devour flying insects with quick airborne twists and turns that show off their chestnut rump patch and forehead. True to its name, it often roosts and nests inside the entrances to caves, sharing the space with bats. More recently, Cave Swallows started nesting under bridges and culverts and expanding their range northward. These colonial nesters collect mud and bat guano with their bills to build a nest that they cement onto walls and ledges.

Although this species is potentially vulnerable to disturbance when nesting, particularly at night, its numbers are expanding in North America and key colonies appear to be stable. Pesticide contamination could be a problem for Cave Swallows in some agricultural areas of the southwestern United States and Mexico, although farming does provide these birds with sources of water and insect foods. Today, we will be talking about the commonly overlooked
but fascinating bird. We will be discussing:

● Cave Swallow Photos, Color Pattern, Song
● Cave Swallow Size, Eating Behavior, Habitat
● Cave Swallow Range and Migration, Nesting

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Cave Swallow Color Pattern

These birds have dark wings and a dark tail, with distinct white streaks that travel across their upper back. Their crown is also a dark color, but their back has a shade of blue. Their rump is buffy, with their throats matching them in color. The underparts of these birds are mostly dull white, with the sides and flanks washed with grayish buff or tawny buff. Their forehead is deep cinnamon. Adults of both sexes are similar to each other in plumage, but the exact differences between them are highly subtle. They look very similar to Cliff Swallows but have a paler throat and more strongly colored sides and flanks.

Juveniles have variable amounts and patterns of white feathers on the forehead and throat, with the head pattern becoming less distinct as they molt into their adult plumage. They also have a pale, buff throat that makes them seem similar to the juveniles of Cliff Swallows.

Description and Identification

Visiting Carlsbad Caverns in New Mexico is an easy way to see a Cave Swallow. They nest inside the main cavern, making it easy to watch them fly in and out. Outside Carlsbad, look for them under bridges, near other caves, or foraging above water. They are often with other swallows, so look for their chestnut rump patch to pick them out of the crowd. Cave Swallows also turn up from time to time in the north-eastern United States. These rarities often show up from late October through mid-November following a fast-moving low-pressure system. Look for these errant birds foraging over water.

Cave Swallow Song

These birds have five main vocalizations, a song, a “che” note, and three types of chattering. Their song is a series of squeaks that gradually blend into a “complex melodic warble” and end in a series of double-toned notes, in which a “gua” sound and a very low nock sound are given simultaneously. These sometimes end with a sharp “ee” note. Their “che” note is a high-pitch nasal note that occurs during flight and in response to birds that are passing near the nest, or to a predator in the area, or to birds chasing a predator.

The most common type of chattering is a short, clear “weet or chweet” that is not too low or high in pitch, but it can either ascend or descend in tone. The second is a high-pitched “che or chu”, mostly given in response to a predator. The last type of chatter is a low, clear “choo”, that is descending in tone and you often hear it when this bird is disturbed. Chicks give faint calls shortly after hatching, but these become louder as they grow older.

Cave Swallow Size

These birds have a cylindrical body that is around 5.5 inches long. They have long and pointed wings that have a wingspan of 13 inches. Their cumulative weight amounts to 0.6–0.9 ounces approximately. They have a square-tipped tail that sometimes shows a slight notch, and their bill is extremely short. They also have small feet that are hard to notice from a distance.

Cave Swallow Behavior

Cave Swallows fly with deep and strong wingbeats interspersed with frequent glides. When they enter a cave, they float down into it and fly back out in a spiral. They spend most of their time aloft but head to the ground to collect tiny balls of mud or bat guano to build a nest. When foraging, they engage in acrobatic flight movements in order to catch flying insects, They walk infrequently, usually only going to the crown to gather mud or other nest material. They are also good climbers.

They collect mud after recent rains or along the edges of rivers and springs with moist soil, mainly for building the nest. While on the ground, they continually flutter their wings. Scientists suggest they could be doing this to confuse predators or to prevent their wings from touching the ground and getting dirty. This is an often occurrence with females while they are on the ground. Males hover over females, and when a female drops her wings for an instant, the male generally drops on her and tries to copulate.

They nest in colonies and forage in single-species groups as well as with other Swallows. They are rarely alone, and are highly social as they constantly interact with each other when foraging in flocks, defending their nest sites against predators, or while bathing and drinking water in large groups. Since these colonies are in small places, territoriality is only exhibited in the immediate vicinities of the nest. While threat and appeasement display need more information, these birds have been observed to defend a nest site while spreading their wings, extending their head, and chattering towards the intruder from the nest entrance.

Paired birds are generally monogamous for the season, but some males have been observed to copulate with multiple females. Their courtship displays, unfortunately, are not well-known either. However, it occurs in flight, with the females arriving first and males following shortly after. After mating, both birds generally fly together while making chattering calls to one and another.

Cave Swallow Diet

Cave Swallows eat flying insects on the wing, foraging at heights up to 350 feet. They consume numerous flying insects such as seed bugs, assassin bugs, short-horned grasshoppers, green lacewings, ladybird beetles, aphids, moths, wasps, bees, and flies. Cave Swallows usually feed in loose flocks throughout the day. They also drink water on the wing, gently skimming the surface of the water with their bill.

Cave Swallow Habitat

These birds are found over semi-open countrysides. They generally forage over any kind of open or semi-open terrain, especially if the area is near a water source. Breeding was initially limited due to the scarcity of nest sites in natural caves and sinkholes. However, they have adapted well to urban areas and now nest under bridges and culverts, buildings, silos, and many other artificial sites. This has allowed the species to spread into new habitats.

Range and Migration

These birds are known to breed in Mexico, south-eastern New Mexico, southern Florida, Greater Antilles, and in areas of Texas. The South American populations, as well as most Mexican and Caribbean populations, are considered resident populations that breed and overwinter in the same geographic range. New Mexico and other northern populations migrate south towards warmer regions. However, it is not known where they migrate to or which migration routes they take. They are presumed to winter in most of the regions where resident populations occur, though it is not known if they fly over open water or take land routes. They have been observed to overwinter in southern Texas since at least the 1980s.

Cave Swallow Lifecycle

Cave Swallows have 1–2 broods in a year, with each brood having a clutch size of 1 to 5 eggs. Both parents most likely incubate the eggs, for a period of around 15–18 days. Once the eggs hatch, the chicks emerge completely naked and in a helpless state. Both parents tend to the nestlings and bring food for them. After an average of 20–26 days, the young ones are ready to leave the nest and assume a life of complete independence.

Nesting

Cave Swallows nest colonially on vertical walls or horizontal ledges, sometimes sharing the area with Cliff Swallows. Historically Cave Swallows only nested in caves or sinkholes, but they now also nest on highway underpasses and culverts. They reuse nests from the previous breeding season, refurbishing them until the weight of the nest causes them to break from the wall.

Males and females collect mud and bat guano with their bills to create a flattened cup made of mud pellets. Sometimes the sides of the nest extend upward to enclose the cup and may have a small entrance tunnel on one side. They line the inside of the nest with grass and plant fibers.

Anatomy of a Cave Swallow

These birds have a cylindrical body that is around 5.5 inches long. They have long and pointed wings that have a wingspan of 13 inches. Their cumulative weight amounts to 0.6–0.9 ounces approximately. They have a square-tipped tail that sometimes shows a slight notch, and their bill is extremely short. They also have small feet that are hard to notice from a distance.

Final Thoughts

Cave Swallows are common, and their populations increased dramatically between 1970 and 2014, according to Partners in Flight, which means it is not on the Partners in Flight Watch List and is a species of low conservation concern. Since the mid-1980s, Cave Swallows have noticeably expanded their range, now occupying Texas and Florida where they nest under bridges and culverts. Cave Swallows are also likely benefitting from increases in irrigated agriculture in the Southwest, which provide good foraging opportunities.

These birds have constantly been expanding their range, a fortunate occurrence for birders that are especially interested in these birds. They are one of the finest examples of birds that are not only adaptive but also cooperative if needed. By taking advantage of the drastically changing conditions of modern times, these birds are as opportunistic as they are clever. By encountering them in their natural or new habitats, one can feel the semblance of how evolution constantly occurs within creatures in response to their environments. Of course, their beautiful plumages and graceful builds are an added bonus that can delight anyone who is lucky enough to catch a glimpse of them.

Ornithology

Bird Watching Academy & Camp Subscription Boxes

At the Bird Watching Academy & Camp we help kids, youth, and adults get excited and involved in bird watching. We have several monthly subscription boxes that you can subscribe to. Our monthly subscription boxes help kids, youth, and adults learn about birds, bird watching, and bird conservation.

Bird Watching Binoculars for Identifying Cave Swallows

The most common types of bird watching binoculars for viewing Cave Swallows are 8×21 binoculars and 10×42 binoculars. Bird Watching Academy & Camp sells really nice 8×21 binoculars and 10×42 binoculars. You can view and purchase them here.

Cave Swallow Stickers

Stickers are a great way for you to display your love for bird watching and the Cave Swallow. We sell a monthly subscription sticker pack. The sticker packs have 12 bird stickers. These sticker packs will help your kids learn new birds every month.

Bird Feeders ForCave Swallows

There are many types of bird feeders. Bird feeders are a great addition to your backyard. Bird feeders will increase the chances of attracting birds drastically. Both kids and adults will have a great time watching birds eat at these bird feeders. There are a wide variety of bird feeders on the market and it is important to find the best fit for you and your backyard.

Bird HousesForCave Swallows

There are many types of bird houses. Building a bird house is always fun but can be frustrating. Getting a bird house for kids to watch birds grow is always fun. If you spend a little extra money on bird houses, it will be well worth every penny and they’ll look great.