Birds
Burrowing Owl
Athene cunicularia · also called burrowing owl, ground owl, howdy owl, billy owl
The burrowing owl breaks most of the rules for an owl. It is out in the daylight, it stands on absurdly long legs at the mouth of a hole in the ground, it lives in that hole instead of a tree, and it decorates its doorway with dung to lure in beetles for dinner.
Overview
Burrowing owls live in open, treeless, short-grass country across the Americas, from the Canadian prairies to Patagonia. They are tiny — about 150–240 g — sandy-brown, with bright yellow eyes, no ear tufts, and long bare legs. They hunt large insects and small mammals from a perch, on foot, or by hovering, and are often active in broad daylight.
Living underground
The burrowing owl is the only North American owl that nests in a ground hole. It usually takes over a prairie dog, ground squirrel, or badger burrow and enlarges it, though in Florida and where no burrows exist it digs its own tunnel 2–3 m long. It often nests in loose colonies near prairie dog towns.
Dung bait
Adults gather cattle, horse, and dog dung and spread it around the burrow. Experiments show this attracts dung beetles that the owls then eat at the doorstep.
Rattlesnake bluff
A threatened owl, especially a chick in the tunnel, gives a hissing rattle that mimics a rattlesnake, deterring badgers and other predators from entering the burrow.
Status
The burrowing owl is Least Concern globally but declining across North America — Endangered in Canada — as grassland is ploughed and burrowing-mammal colonies are poisoned out.
Burrowing Owl: common questions
Do burrowing owls really live underground?
Yes. The burrowing owl is the only North American owl that nests and roosts in a hole in the ground rather than in a tree, cliff, or building. Across most of its range it does not dig the hole itself; it moves into a burrow abandoned or still used by a colonial rodent such as a black-tailed prairie dog or a ground squirrel, or one made by a badger, armadillo, or gopher tortoise, and then modifies it, sometimes creating a nest chamber a metre or more down at the end of a two-to-three-metre tunnel. The Florida subspecies and owls in areas without suitable rodent burrows will excavate their own, using their beak and kicking soil back with their long legs and feet. Because they depend on burrows, the decline of prairie dogs has hit burrowing owls hard.
Why does a burrowing owl put dung around its nest?
Burrowing owls deliberately collect dried and fresh mammal dung and spread it in and around the burrow entrance. Experiments have shown the main function is baiting — the dung attracts dung beetles and other insects, which the owls then catch and eat right at the doorstep, significantly boosting the food they can get without leaving the nest. Earlier ideas that the dung mainly serves to disguise the owls' own scent from predators, or to signal that a burrow is occupied, are probably secondary at most. When researchers removed the dung and provided extra beetles, the owls ate far more; when they removed the dung and the beetles, hunting success dropped.
Why do burrowing owls hiss like rattlesnakes?
When an intruder such as a badger, fox, snake, or ground squirrel approaches the burrow, an adult or, more often, a nestling retreats into the tunnel and produces a drawn-out, buzzing, hissing rasp that sounds strikingly like the rattle and hiss of a defensive rattlesnake. The confined space of the burrow amplifies and distorts the sound. The likely benefit is that a predator hearing a "rattlesnake" in a dark hole will hesitate or leave rather than push in, since many of the animals that would raid an owl burrow are themselves vulnerable to a rattlesnake bite. It is considered a form of acoustic Batesian mimicry.
Are burrowing owls endangered?
The species as a whole is listed as Least Concern because it still has a very large range and, in parts of South America and the southwestern US, remains common. But it has declined substantially across much of North America. In Canada it is federally Endangered and has vanished from large parts of the prairie provinces; several US states list it as threatened, endangered, or a species of special concern; and it has disappeared from many former areas of California and the Great Plains. The reasons are the conversion of native grassland to intensive crops, the poisoning and eradication of prairie dogs and ground squirrels whose burrows the owls need, road mortality, pesticides reducing insect prey, and development of the open ground the owls favour.