The Burrowing Owl (Athene cunicularia) is a small, long-legged owl found throughout open landscapes of North and South America. Burrowing owls can be found in grasslands, rangelands, agricultural areas, deserts, or any other dry, open area with low vegetation. They nest and roost in burrows, such as those excavated by prairie dogs (Cynomys spp.). Unlike most owls, burrowing owls are often active during the day, although they tend to avoid the mid-day heat. Most hunting is still done from dusk until dawn, when their owl apomorphies are most advantageous.
Males and females are similar in size and appearance. The female bird is darker in color, however, adult males appear lighter in color because they spend more time outside the burrow during daylight, and their feathers become "sun-bleached". The average adult is slightly larger than an American robin (Turdus migratorius), at 25 cm (10 inches) length, 53 cm (21 inches) wingspan, and 170g (6 oz).
The typical who who call of a burrowing owl is associated with territory defense and breeding, and is often given by adult males to attract a female to a promising burrow. They also make other sounds, which are described as chucks, chattering, and screams. These sounds are usually accompanied by an up and down bobbing of the head. When alarmed, young birds will give a hissing call that sounds like a rattlesnake.
They range from the southern portions of the western Canadian provinces through southern Mexico and western Central America. They are also found in Florida and many Caribbean islands. In South America, they are patchy in the northwest and through the Andes, but widely distributed from southern Brazil to Patagonia and Tierra del Fuego. Burrowing owls are year-round residents in most of their range. Birds that breed in Canada and northern USA usually migrate south to Mexico and southern USA during winter months.
This species is able to live for at least 9 years in the wild and over 10 years in captivity. They are often killed by vehicles when crossing roads, and have many natural enemies, including badgers, coyotes, and snakes. They are also killed by both feral and domesticated cats and dogs. Two birds studied in the Parque Nacional de La Macarena of Colombia were free of blood parasites.
The burrowing owl is endangered in Canada, threatened in Mexico, and a species of special concern in Florida and most of the western USA. It is common and widespread in open regions of many Neotropical countries, where they sometimes even inhabit fields and parks in cities. In regions bordering the Amazon Rainforest they are spreading with deforestation. It is therefore listed as Least Concern on the IUCN Red List. Burrowing owls are protected under the Migratory Bird Treaty Act in Canada, the United States, and Mexico. They are also included in CITES Appendix II.
The major reasons for declining populations in North America are control programs for prairie dogs and loss of habitat, although burrowing owls readily inhabit some anthropogenic landscapes, such as airport grasslands or golf courses. Genetic analysis of the two North American subspecies indicates that inbreeding is not a problem within those populations.
Where the presence of burrowing owls conflicts with development interests, a passive relocation technique has been applied successfully: rather than capturing the birds and transporting them to a new site (which may be stressful and prone to failure), the owls are half-coerced, half-enticed to move on their own accord. The preparations need to start several months prior to the anticipated disturbance with observing the owl colony and noting especially their local movements and site preferences. After choosing a location nearby that has suitable ground and provides good Burrowing Owl breeding habitat, this new site is enhanced by adding burrows, perches, etc. Once the owls have accustomed to the changes and are found to be interested in the location - if any possible, this should be at the onset of spring, before the breeding season starts - they are hindered to enter the old burrows. A simple one-way trapdoor design has been described that is placed over the burrow for this purpose. If everything has been correctly prepared, the owl colony will move over to the new site in the course of a few nights at most. It will need to be monitored occasionally for the following months or until the major human construction nearby has ended.
For more information (background, pictures, experiments and references): The Burrowing Owl
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