The burrowing owl is a tiny, long-limbed owl that can be found across the open terrain of North and South America. They can be seen in grasslands, deserts, agricultural areas, rangelands, or any other available dry region with low vegetation.
They dwell in caves similar to those dug up by prairie dogs. Unlike most owls, burrowing owls are always enthusiastic during the day. However, they sometimes show a tendency to avoid the midday heat.
Just like many other species of owls, burrowing owls does majority of their hunting at night, when they can make use of their night vision and hearing to their benefit.
As a result of them residing in open grasslands, burrowing owls have acquired longer limbs that allow them to run, and also fly while hunting.
Burrowing owls possess colourful eyes, and their beaks could be grey or dark yellow depending on the subspecies. They lack ear clumps and have a compressed facial disc.
The owls have notable white eyebrows and a white chin patch which they can broaden and display during specific behaviours, that include bobbing of the head when irritated.
Adult owls have brown heads and wings with a noticeable spotting. The chest and abdomen are white with irregular brown barring, which also depends on the subspecies.
Young owls are comparable in appearance, yet they lack the white spotting and brown barring feature. Young burrowing owls possess a buff bar surrounding the upper wing, and their breast may be buff-coloured instead of white.
Male and female burrowing owl are comparable in size as well as their appearance and exhibit slight sexual dimorphism. Female burrowing owls are more prominent, while males tend to have more extended linear dimensions (tail length, wing length, and more).
Adult males seem brighter in colour than females because they spend longer period outside the burrow in the day, and their feathers become faded.
The burrowing owl measures about 19 – 28 cm (7.5 – 11.0 in) in length, ranges 50.8 – 61 cm (20.0 – 24.0 in) across the wings and weighs 140 – 240 g (4.9 – 8.5 oz). As a size comparison, a typical adult is slightly bigger than an American robin (Turdus migratorius).
The burrowing owl is occasionally categorized in the monotypic genus Speotyto, which is centred on different karyotype and morphology. Nevertheless, osteology and DNA sequence data indicate that the burrowing owl is a terrene member of the Athene little owls, and it is recognized as part of the genus class by most authorities.
A substantial number of subspecies were described, but they vary slightly in appearance and the taxonomy of many need to be validated. Most subspecies are seen around the Andes and in the Antilles. Although they’re distinct from one another, the relationship of the Florida subspecies to (and its distinctness from) the Caribbean birds is not entirely clear.
A paleosubspecies, A. c. providentiae were discovered from fossil remnants found in the Pleistocene of the Bahamas. It’s still a mystery how these birds are associated with the existing A. c. floridana and whether they were amongst the ancestors of that subspecies. It is also unclear if they symbolize a more distant species that completely vanished later.
Additionally, early fossils of identical owls have been recovered from several islands in the Caribbean that include Barbuda, Mona Island, Jamaica, the Cayman Islands, and Puerto Rico.
These birds became extinct at the end of the Pleistocene. This could be as a result of the ecological and sea-level changes toward the end of the last Ice Age. These fossil owls vary in size from present-time burrowing owls, and their connection to the modern taxon has not been determined.
Before European colonization, burrowing owls presumably occupied every favourable region of the new world. However, they have encountered some limitations during distribution in North America.
In some parts of South America, they are increasing their scope with deforestation. The western burrowing owls are widespread in the Rocky Mountain Arsenal National Wildlife Refuge and some counties in Colorado. They have also been stated to be in danger of extinction.
Burrowing owls span from the southern parts of the western Canadian districts through southern Mexico and western Central America. They can also be discovered in Florida and several Caribbean islands.
In South America, they are scarce in the northwest and through the Andes, but extensively dispersed from southern Brazil to Tierra del Fuego and Patagonia. Burrowing owls that thrive in Canada and the northern U.S. often migrate to Mexico as well as the south of the U.S. during the winter period.
Ecology and Behaviour
Burrowing owls can live for a minimum of nine years in the wild and over ten years in captivity. They are usually killed by vehicles while crossing roads and have several natural enemies, including coyotes, badgers, and snakes. Burrowing owls are also killed by both domestic and wild cats & dogs.
Burrowing owls dwells in the holes dug by ground squirrels, a technique also utilized by rattlesnakes. When the owl feels threatened, they retreat to the burrow and create hissing sounds identical to that of a rattlesnake.
The behaviour is inferred to be an example of acoustic Batesian mimicry. It has been identified to be an effective method against animals that are aware of the dangers posed by rattlesnakes.
When owls hunt, they linger on a pole until they sight their prey. Then, they dive down on target or fly up to grab insects in flight. Occasionally, they chase target on foot. The highly flexible diet constitutes invertebrates and small vertebrates, which comprise around one-third and two-thirds of their diet, respectively.
Burrowing owls mostly consume large insects and little rodents. However, burrowing owls rarely prey upon ground squirrels. Unlike other owls, they also eat seeds and fruits, especially the fruit of tasajillo and other thorny pear and cholla cacti.
The breeding season of burrowing owls starts in late March or April in North America. They usually have only one mate, but sometimes a male burrowing owl can have two mates. Pairs of owls often nest in relaxed territories, and their common breeding habitat is open grassland or prairie.
Nonetheless, they can sometimes adapt to other available places such as golf courses, airports, and agricultural fields. Burrowing owls are barely tolerant of human presence, always nesting near farms, roads, homes, and adequately maintained irrigation canals.
During the mating season, burrowing owls will gather various materials to bound their nest, some of which are left all over the entrance to the burrow. The most popular material is mammal dung, usually from cows.
At some point, it was assumed that the waste helped in masking the scent of the young owls, but scientist now believes that the manure helps to regulate the microclimate inside the burrow and to lure insects, which the owls can eat.
The female burrowing owl tends to lay an egg every one or two days until she has completed a batch. This batch typically includes 4 to 12 eggs. The female burrowing owl will then incubate the eggs for about three to four weeks while the male gets her food.
After each egg has hatched, both parents share the responsibility of feeding their nestlings. The owlets can make brief flights and try leaving the nest burrow after four weeks of hatching. However, the parents will support them for another one to three months.
Tract fidelity rates seem to differ among the populations of burrowing owls. In some locales, owls will often reuse a burrow for many years in a row. Owls in northern migratory populations are less inclined to return to the same nest each year. Just like many other birds, the female owls are more likely to distribute to various areas than the male burrowing owls.
The burrowing owls are threatened by several countries like Canada, Mexico, Colorado, and Florida. It is widespread in open areas of many Neotropical states, where they occasionally occupy fields and parks in cities.
Farmers, as well as landowners, are encouraged not to disturb areas where burrowing owls reside. They are also urged to utilize alternative pesticides or lower amounts of these chemicals.
This will help preserve the existence of these birds for a more extended period.