by Frank Keim
I call these nimble swallows “mud daubers” because they build their nests of mud. Watch them as they do this in early spring and you’ll see them fly down to a mud puddle, stream bank or lakeside, pick some of the mud up in their bills, mix it with their saliva, then jet back over to a vertical rock cliff with a horizontal overhang or under the eaves of a building or bridge and slowly fashion the work of art that will become their nest for a month and a half.
Since these swallows are birds that nest in colonies, their mud nests are built in clusters. In some areas of North America these clusters can number up to 3,700 nests in one spot. When a Cliff swallow is home you can plainly see its bright forehead glowing from the dim entrance.
I found two Yup’ik names for the little bird: Ngel’ulluiraq, which is the most common name and refers to the small dent in its tail; and Puyuqnirtaraq, which alludes to the smoky color of its wing and tail feathers. Its scientific name, Petrochelidon pyrrhonota, is a combination of Greek and Latin names meaning, “red-rumped swallow that nests on rock cliffs” Golondrina Risquera is their Spanish name and Hirondelle a front blanc is their French name.
Cliff swallows eat flying insects year around, sometimes foraging in flocks of more than a thousand birds, and often taking advantage of thermal air currents that bring together dense swarms of insects. When insects are less plentiful, you will find the birds feeding over lakes, ponds, and rivers. If an individual has a hard time finding food for its young, it will watch its neighbors in the colony and follow one of them to its food source when it leaves. If a swallow finds food away from the colony during poor weather conditions it may give a specific call to alert other swallows of the food source. By alerting others to a large insect swarm an individual can ensure that the swarm is tracked and can be followed effectively.
After the swallows return to the Y-K Delta in May, the male courts a female with an aerial dance and sweet rapid twittering. After pairing up, the couple first chooses a colony, and either takes over an existing nest from the previous year or selects a space in the colony to build a new nest. Both sexes help build the nest, although an unattached male may begin building before he attracts a mate. They bring mud pellets back in their bills and mold them into place with a shaking motion. When finished, the gourd-shaped nest will contain between 900-1200 individual mud pellets. The pair lines their nest with dried grass and continues patching it with mud throughout the breeding season. They defend their nest by sitting in the entrance, puffing up their head and neck feathers to look larger, and lunging at intruders. Although the birds sleep in trees for most of the year, a female in the process of building her nest will begin sleeping there as soon as it is partly finished. Although each bird has only one mate with whom it raises young, both male and female frequently breed outside the pair bond. All mating happens in mid-flight as the birds are foraging for flying insects.
Up to six pinkish white, brown-spotted eggs are laid, and both parents help incubate them for 14-16 days. During that period, a couple of interesting things may happen within a Cliff swallow colony. Sometimes a swallow will lay eggs in another swallow’s nest. Or it may lay eggs in its own nest, then carry one of its eggs in its bill and put it in another female’s nest. Why, is not completely understood and must remain a mystery for the time being.
Both parents also help feed the nestlings, and after 21-23 days the young birds generally feel confident enough to step out onto the threshold of their mud house and leap into flight. After they fledge, they congregate in large groups called crèches. Their parents can find their young in the crèche primarily by voice, but the fledglings have such distinctive plumage and facial markings that these traits also help their parents recognize them.
Hanging out in large crèches is a good strategy to confuse predators, especially Peregrine falcons that hunt them ferociously below their aeries located high above on the same rock cliffs.
Back in the mid-1990’s, while helping a friend do a Peregrine falcon survey on the Porcupine River in the Arctic National Wildlife Refuge, we watched these swallows being chased by adult Peregrines with hungry young still in their own nests. They stooped on them at high speed, but were often foiled by the young swallows when they all scattered in different directions. Even if a falcon was able to hone in on a single bird over the river, it quite often escaped its talons by plunging headfirst into the water and diving over and over under the water until the falcon lost interest and targeted another bird.
Both adult and young cliff swallows continue to congregate in large flocks all year, flying, feeding, preening, drinking and bathing in groups. Even during their long migration and on the grasslands and marshes of their wintering grounds in southern South America they also stick together.