Burrowing owls are a species of small owl that live in open, treeless areas. They get their name from their habit of nesting underground in burrows dug by other animals like prairie dogs, ground squirrels, and tortoises. Once widespread across grasslands and deserts of North and South America, burrowing owl populations have been declining in many parts of their range over the past several decades. There are several reasons why burrowing owls are disappearing, most relating to human activities and habitat loss.
Habitat Loss
One of the main causes of burrowing owls’ decline is the loss and fragmentation of their natural grassland habitats. As native prairies and plains are converted to agricultural land, covered in development, or otherwise altered, it removes the open spaces that burrowing owls rely on for nesting, roosting, and hunting. For example, it is estimated that less than 2% of tallgrass prairie habitat remains in North America today compared to historical levels. With less habitat available, burrowing owl populations decline.
Some specific ways habitat loss impacts burrowing owls:
- Plowing and conversion of grasslands to farmland destroys burrowing owl burrows and removes vegetation cover they use for nesting and shelter.
- Development of rural and suburban areas replaces open space with unsuitable habitats like buildings, roads, and landscaping.
- Habitat fragmentation from roads, fences, and other infrastructure divides up remaining habitat into smaller, disconnected patches that may not support sustainable owl populations.
- Habitat degradation from overgrazing by livestock, fire suppression, and invasive plant species can alter vegetation structure and eliminate burrowing mammals owls rely on for nesting burrows.
As their breeding and hunting grounds disappear across North America, burrowing owls lack sufficient habitat to maintain thriving populations in many parts of their historic range.
Decline of Burrowing Mammals
Burrowing owls are somewhat unique among owls in that they nest underground in burrows dug by other species, rather than tree cavities or crevices. They are dependent on the presence of burrowing mammals like prairie dogs, ground squirrels, and tortoises to provide suitable nesting sites. Without access to abandoned burrows, burrowing owls struggle to reproduce and raise young.
Unfortunately, many of the mammals that dig burrows helpful to owls have also experienced population declines. Prairie dogs in particular have been deemed a nuisance species and systematically eradicated from much of their native range. As prairie dogs and other burrowing mammals disappear, so do the burrows and nesting opportunities they provide for burrowing owls. The owls are left with fewer and fewer suitable places to nest and breed.
Predators and Competition
Burrowing owls face threats not just from habitat loss but also from natural predators. Common predators of eggs or young owls include coyotes, badgers, snakes, and weasels. In some cases, predation risk may be higher in fragmented or degraded habitats where burrowing owls are forced into closer proximity with predators and have fewer burrow options to hide in.
Burrowing owls also face competition from other species vying for their burrow nests. In particular, the larger Western burrowing owl has expanded its range east and may compete with smaller burrowing owls for nesting sites. Tree-nesting owls like barn owls may also take over burrowing owl burrows, forcing the burrowing owls out of nests they depend on for breeding.
While predation and competition are natural processes, habitat degradation and fragmentation appears to be giving rival species and predators an upper hand in many areas at the expense of burrowing owls.
Vehicle Collisions
Roads and vehicular traffic pose another threat to burrowing owl populations, especially in landscapes fragmented by urban or suburban development. Owls nesting, roosting, or hunting near roads are at risk of being struck by cars or trucks as they fly low to the ground. Vehicle collisions account for a significant portion of burrowing owl deaths in many areas.
One Canadian study found that up to 14% of radio-tagged burrowing owls were killed on roads over the course of a single breeding season. This level of road mortality is high enough to potentially impair population growth and contribute to the owls’ disappearance from developed areas with high road density. Installation of reflectors, warning signs, and wildlife passages may help reduce road mortality in key areas.
Shooting and Poisoning
Though illegal and unethical today, burrowing owls were once commonly shot by farmers and ranchers who viewed them as pests. The use of poisoned bait to kill prairie dogs and other burrowing mammals also led to secondary poisoning of the owls that preyed upon them. While such direct persecution has declined, shooting and poisoning may still threaten some burrowing owl populations. Public education and law enforcement can help ensure protection of these protected migratory birds.
Climate Change
Some research indicates climate change could contribute to burrowing owl declines in the future. Rising temperatures, drying conditions, and reduced rainfall projected for parts of their range could result in less productive breeding habitats. Loss of burrowing mammal populations may also be exacerbated if climate shifts reduce vegetation supporting prairie dogs, ground squirrels, and other burrow creators. Continued monitoring and habitat conservation will be necessary to help burrowing owls adapt to a changing climate.
Conservation Efforts
While burrowing owl populations have declined significantly in many regions, some conservation efforts are working to protect these unique owls and their habitats:
- Breeding programs at zoos and captive breeding facilities help maintain genetic diversity in owls used for bolstering wild populations.
- Installation of artificial nest boxes and burrows provides extra breeding options for owls in areas with burrow shortages.
- Predator control and monitoring may help reduce nest predation rates for owl populations in some high-risk areas.
- Habitat restoration and protection on public and private lands preserves or reestablishes breeding and foraging grounds.
- Nest protection programs temporarily limit disruptive human activities near owl nests during breeding season.
- Road signs, reflectors, and wildlife passages help owls coexist with vehicles in developed areas.
- Community science efforts like citizen scientists tracking owl nests and populations provide valuable monitoring data to guide conservation.
With sustained effort and public interest, it may be possible to slow or even reverse declining burrowing owl trends. But more habitat protections, breeding support, and reducer threats will be key to ensure these charismatic owls keep their place in North America’s grasslands.
Conclusion
Burrowing owls are struggling across significant portions of their range as human development and environmental pressures eliminate the grasslands and burrows they rely on for nesting and shelter. Loss of breeding habitat and burrowing mammal populations, vehicle collisions, predation, and climate impacts are all contributing to declines. However, burrowing owl conservation does show promise through habitat restoration, breeding assistance, threat reduction, and monitoring programs. With adequate protections and public engagement, it is hopefully not too late to bring burrowing owls back from the brink and secure their long-term survival across their native habitats. These dedicated conservation efforts are critically important to preserve the ecological roles and intrinsic worth of these small, subterranean owls into the future.