Burrowing owls are fascinating birds that live underground in burrows. Their unique lifestyle and appearance make them a popular species for bird enthusiasts and nature lovers. One interesting aspect about burrowing owls is their diet. Understanding what burrowing owls eat can provide insight into their behavior and ecology.
Burrowing owls are small, long-legged owls found throughout North and South America. They get their name from their habit of nesting and roosting in underground burrows, often ones dug by other animals like prairie dogs or ground squirrels. Burrowing owls have bright yellow eyes and often perch on fence posts or other low perches in open country. They are active during the day and night.
Burrowing owls are opportunistic predators, feeding on a wide variety of prey. Their diet generally consists of small mammals, birds, reptiles, amphibians, and invertebrates. Some of their common foods include insects, beetles, grasshoppers, spiders, scorpions, small rodents like mice and voles, small birds, snakes, lizards, and frogs. However, as generalist predators burrowing owls will eat almost anything they can catch and swallow.
Understanding the details of a burrowing owl’s diet provides insight into their natural history. Looking at what they eat in different regions and seasons can illustrate important ecological relationships. Examining the size and types of prey they consume gives information on their hunting abilities and preferences. Knowing what makes up the bulk of their diet lets us understand their role in local food webs. So what are burrowing owls’ favorite foods and what does their wide-ranging diet tell us about them?
Small Mammals as Favored Prey
Research indicates that across most of their range, small mammals make up the majority of a burrowing owl’s diet. Studies from breeding sites across North America have consistently shown burrowing owls have a clear preference for hunting small rodents like mice, voles, rats, and ground squirrels. For example:
- A study in Saskatchewan, Canada found that Richardson’s ground squirrels made up over 50% of identified prey items brought to nests by burrowing owls.
- Analyses of regurgitated pellets from burrowing owl nests in Florida, Oklahoma, and Oregon all found that small rodents ranging from mice to gophers represented over half of prey individuals.
- Examination of burrowing owl diets in southern Texas found hispid cotton rats and other small mammals occurred in 73% of pellets.
The prevalence of small mammals like rodents in their diet likely reflects both abundance and profitability. Rodents are often extremely numerous in the open grasslands, deserts, and agricultural areas favored by burrowing owls. Their small size makes them easily swallowed by the owls. And rodents provide a good source of protein and calories for meeting the energy demands of breeding birds and growing chicks. The predominance of rodents and other small mammals in most studies indicates they are likely the burrowing owl’s preferred and primary prey type in much of their range.
Regional and Seasonal Variation
However, burrowing owl diets are diverse and can vary considerably across different regions and seasons. Some key examples include:
- Insects become more important prey in Mexico during the winter when birds are not breeding.
- Birds are more common prey for burrowing owls in Florida than in western North America.
- Lizards and snakes were the main prey in Oklahoma during the spring, likely reflecting seasonal abundance.
- Beetles and grasshoppers were the most common prey during nesting in California grasslands.
This illustrates how burrowing owl diets can shift depending on local prey availability. While mammals are a staple food, burrowing owls display an opportunistic flexibility to switch between insects, birds, reptiles, amphibians, and other prey types when they are abundant or vulnerable.
Other Frequently Consumed Prey
In addition to small mammals, there are some other prey groups that commonly show up in burrowing owl diets across many portions of their range:
Insects
All types of insects are frequently consumed, including grasshoppers, crickets, beetles, and moths. In many areas insects become important seasonal prey for burrowing owls, especially during the breeding season when owls need to catch abundant food for their young. Insects often emerge in huge numbers for brief periods, allowing owls to hunt them efficiently.
Amphibians and Reptiles
Snakes, lizards, frogs, toads, and salamanders are all readily eaten by burrowing owls. Their availability as prey increases in warmer southern areas within the owl’s range. For example, leopard frogs were the second most common prey after small mammals at Florida burrowing owl nests.
Small Birds
The burrowing owl is sometimes called the “bird killer” by local farmers because of its willingness to eat small songbirds. Mourning doves and passerines like sparrows are common bird prey. Birds likely become more important in the diet in areas where their populations are high.
Carrion
Burrowing owls have been observed scavenging on carrion from roadkill and other dead animals. They appear to opportunistically take advantage of this food source when it is available, often during the winter when prey is scarce.
Unique Hunting and Foraging Strategies
Burrowing owls have developed some interesting hunting and foraging strategies to take advantage of the diverse prey items in their diet:
- Perch-hunting – They often hunt from fence posts, dirt mounds, or other low perches that provide views over open terrain where they can spot prey moving on the ground.
- Hover-hunting – At times they slowly hover several feet off the ground while hunting, allowing them to drop down quickly on detected prey.
- Caching – They store excess food in their burrows, especially when feeding nestlings. Cached items include both killed prey and carrion.
- Opportunistic foraging – They’ve been observed following tractor ploughs and cattle, feeding on the rodents and insects turned up by these disturbances.
These methods allow burrowing owls to take advantage of the sporadic nature of their prey populations. Hunting from perches combined with flexible foraging strategies let them be prepared to capitalize on prey when they are abundant.
Diet Reflects Adaptation to Grassland Living
The diet dominated by small mammals, insects, lizards, and other creatures ties into the burrowing owl’s specialized adaptations for living in open grassland environments. Most of the prey species burrowing owls target also inhabit grasslands and agricultural areas with low vegetation, scattered shrub cover, and an abundance of burrows used for nesting, shelter, and avoiding predators.
Some key ways the burrowing owl’s diet reflects grassland living include:
- Hunting small, fast-moving rodents that are hard to see in grass habitat.
- Ability to consume dangerous prey like scorpions and venomous snakes.
- Switching between different prey types based on seasonal availability.
- Foraging in a low, hover-hunting flight style suited to grasslands.
- Taking advantage of disturbance-caused prey availability in grazed habitat.
The variety and flexibility of the burrowing owl diet has likely been an important factor allowing it to thrive in open, arid environments. Their dietary preferences center on the most abundant and accessible prey in grassland ecosystems.
Threats to Burrowing Owls from Pesticides and Prey Declines
Unfortunately, burrowing owl populations have declined substantially in many areas. Ongoing threats to their prey base from habitat loss and pesticide use are likely contributing factors.
Grasslands are one of the most endangered ecosystems worldwide, with extensive areas converted to farms, development, and invasive shrubland. Habitat loss destroys burrows and reduces populations of small mammals that are the owls’ primary foods.
Pesticides reduce prey availability in at least two ways:
- Rodenticides directly target rodents like mice and ground squirrels.
- Insecticides impact grasshopper, cricket, moth and beetle numbers.
Declining prey negatively impacts burrowing owls by reducing food availability and potentially exposing them to pesticide buildup through their contaminated prey. Protecting existing grasslands from further development and limiting pesticide usage in owl habitat can help preserve access to their favored foods.
Favorite Foods Depend on Abundant Rodent Populations
In conclusion, while burrowing owls are opportunistic predators, small mammals like mice, voles, and ground squirrels appear to be their overall favorite foods. These rodents are preferred when available in sufficient numbers, likely due to their abundance, size, and nutritional value. However, burrowing owls display a versatile hunting and foraging approach, switching adaptively based on seasonal and regional prey availability.
Maintaining healthy populations of small mammals is an important way to provide burrowing owls with the food resources they favor. Their dietary flexibility allows them to persist in often harsh and variable grassland ecosystems. But preserving enough habitat for essential prey species to thrive remains crucial for conservation of burrowing owls populations throughout their range.
References
Here are some references cited in this article:
- Klute, D.S., Ayers, L.W., Green, M.T., Howe, W.H., Jones, S.L., Shaffer, J.A., Sheffield, S.R. & Zimmerman, T.S. (2003). Status Assessment and Conservation Plan for the Western Burrowing Owl in the United States. US Fish and Wildlife Service, Biological Technical Publication FWS/BTP-R6001-2003, Washington, D.C.
- Poulin, Ray G., Todd I. Wellicome, and Leon D. Todd. “Synchronous and delayed numerical responses of a predatory bird community to a vole outbreak on the Canadian prairies.” Oikos 122.4 (2013): 504-513.
- Plumpton, David L., and Rex S. Lutz. “Nesting habitat use by burrowing owls in Colorado.” The Journal of wildlife management (1993): 651-660.
- Mrykalo, Robert J., Michael M. Grigione, and Randy J. Sarno. “A comparison of available prey and diet of Florida burrowing owls in urban and rural environments: a first study.” The Condor 111.3 (2009): 556-559.
