Sage thrashers (Oreoscoptes montanus) are medium-sized songbirds found in the arid regions of western North America. They get their name from their preference for sagebrush habitats. Sage thrashers are omnivorous, feeding on a variety of plant and animal material. Their diet changes depending on the time of year and food availability.
Insects and Arthropods
Insects and other arthropods make up a major part of the diet of sage thrashers during the breeding season which lasts from late spring through summer. Sage thrashers forage on the ground or in low vegetation searching for beetles, grasshoppers, caterpillars, ants, and spiders. They also sometimes fly out from perches to catch insects in mid-air. Sage thrashers use their curved bill to probe into crevices and flip over leaves and debris looking for hidden insects.
Some key insects and arthropods eaten by sage thrashers include:
- Beetles
- Grasshoppers
- Caterpillars
- Ants
- Spiders
- Crickets
- Earwigs
- Flies
- Moths
- Centipedes
In one study of sage thrasher diets in Idaho, beetles alone accounted for over 15% of their food intake during the breeding season. The abundance of insects and arthropods enables adult sage thrashers to find food to feed their young. Nestlings are fed insects almost exclusively during their first week after hatching.
Fruit and Seeds
Sage thrashers switch over to eating more plant material in late summer, fall, and winter when insect numbers decline. They consume a wide variety of wild fruits and seeds that become ripe and abundant at this time of year. This includes fruits from trees, shrubs, vines, and herbaceous plants.
Some of the main fruits and seeds consumed by sage thrashers include:
- Serviceberries
- Chokecherries
- Elderberries
- Wild roses
- Grapes
- Nightshades
- Bur oak acorns
- Juniper berries
- Mistletoe berries
- Russian olive fruits
- Prickly pear fruits
- Sumac seeds
- Grass seeds
Sage thrashers use their curved bill to pluck small fruits and can sometimes be seen balancing on branches reaching for berries. They often swallow fruits whole. For seeds, sage thrashers use their bill to crack open seed hulls and extract the inner seed. Sage thrashers have been observed using tools like rocks to help break open hard seeds.
Other Foods
Though insects, fruits, and seeds make up the majority of their diet, sage thrashers are opportunistic foragers and will eat a wide range of other food items depending on availability:
- Grains – Sage thrashers sometimes feed on wheat, barley, and oats in agricultural fields or weedy patches.
- Nectar – Sage thrashers drink nectar from flowers such as sunflowers, thistles, and dellas.
- Sap – They occasionally feed on the sap of trees by pecking into holes made by woodpeckers.
- Lizards – Small lizards are sometimes preyed upon, especially in the southwest part of their range.
- Carrion – Sage thrashers will scavenge dead animals for meat.
By being flexible in their eating habits, sage thrashers are able to adapt to changes in food availability across the seasons and make use of whatever food resources they find while foraging.
Foraging Behavior
Sage thrashers have several distinctive foraging behaviors and adaptations that help them find such a wide array of food:
- Perch and Pounce – Sage thrashers will often perch on an elevated vantage point like a shrub or fence post and look for prey on the ground below. When they spot something, they swoop down quickly to grab it before returning to their perch.
- Ground Foraging – Much of their foraging takes place while walking along the ground. They use their bill to flip over leaves, sticks, rocks, and other debris looking for hidden insects and larvae.
- Foliage Gleaning – Sage thrashers pick insects, spiders, and fruit directly from the leaves and branches of vegetation. Their curved bill helps pluck items out.
- Hovering – At times, sage thrashers will hover briefly in front of a flower or other food source to grab prey.
- Tool Use – As mentioned, sage thrashers use tools like rocks to help crack open hard seeds or access hiding insects.
Sage thrashers exhibit great versatility and adaptability in their foraging strategies. Their flexible food habits and efficient foraging techniques allow them to flourish in harsh sagebrush environments where food can be scarce.
Habitat and Range
The diet and foraging habits of sage thrashers have evolved in direct relation to the sagebrush habitats they occupy. Sage thrashers are specialists of the sagebrush ecosystem which covers millions of acres across western North America.
They are found in the following 11 states and provinces:
- California
- Oregon
- Washington
- Idaho
- Nevada
- Utah
- Wyoming
- Colorado
- Montana
- British Columbia
- Alberta
Within their broad range, sage thrashers inhabit areas dominated by sagebrush species such as big sagebrush, black sagebrush, and silver sagebrush. The sagebrush provide cover and nesting sites, while the variety of grasses, forbs, and shrubs found intermixed in this habitat supply ample food. Many of the insects, fruits, and seeds favored by sage thrashers are directly tied to plants found in the sagebrush ecosystem.
Breeding and Nesting
The food requirements of sage thrashers change dramatically during breeding season when adults must provision hungry nestlings. Sage thrashers typically raise one brood per year with nesting activity centered around late spring and early summer.
Key aspects of sage thrasher breeding and nesting behavior include:
- Clutch Size: 3-6 eggs
- Incubation: 10-17 days
- Fledging: 8-15 days
- Nestlings: fed exclusively insects at first
- Nest site: low in sagebrush, oak, serviceberry
Female sage thrashers build a sturdy nest out of twigs, bark, grass, and sagebrush leaves in the low branches of a shrub. Both parents participate in incubating the eggs. The nestlings hatch after about two weeks and fledge from the nest after another week or two.
The protein-rich diet of insects is critical for the growing nestlings. Adults make frequent trips back and forth to deliver food to the nest. A single sage thrasher chick may consume over 1,000 insects before leaving the nest! Parents continue to bring their fledglings food for several more weeks.
Adaptations for Diet
Sage thrashers exhibit several key physical and behavioral adaptations that aid their diet:
- Curved bill – perfectly shaped for prying open seeds or plucking berries
- Large eyes – help spot insects and fruits while foraging
- Cryptic coloration – mottled brown plumage blends into sagebrush
- Scratching feet – rake away debris while walking to uncover food
- Caching behavior – stores excess seeds and insects for later use
- Highly territorial – year-round territories provide dependable food supply
Interestingly, the shape of their bill is different than that of close taxonomic relatives like the curve-billed thrasher. This suggests the sage thrasher’s bill has been modified over time specifically for its sagebrush food sources.
Diet Changes by Season
The diet of sage thrashers shifts in relation to seasonal changes in food availability:
Spring
April – June
- Mainly insects (caterpillars, beetles, ants)
- Occasional seeds and fruits
- Important for feeding nestlings
Summer
July – August
- Insects, fruits, seeds
- Insects decrease, fruits ripen
- Fledglings still require much food
Fall
September – November
- Emphasis shifts to fruits and seeds
- Caching behavior increases
- Preparing for winter
Winter
December – February
- Relies on cached seeds and fruits
- Less insect food available
- Still maintains territories
While sage thrashers eat a mix of plant and animal foods year-round, the proportions shift significantly depending on season and breeding stage. Their flexible foraging behavior allows them to take advantage of the most readily available food sources in their harsh sagebrush habitat.
Conclusion
In summary, sage thrashers are dietary generalists adapted to the sagebrush ecosystems of western North America. They consume a wide variety of insects, fruits, seeds, and other food sources. Their diet changes across seasons and shifts based on food availability and energy needs. Key adaptations like their curved bill help them access food resources. Sage thrashers play an important role in their habitat by dispersing seeds and controlling insect populations. Their flexible diet and foraging strategies allow them to thrive in the arid sagebrush regions they call home.
