Harris’s sparrows are small songbirds that breed in Canada and parts of the northern United States. They migrate south for the winter, with large numbers of them wintering in the Great Plains and Midwest. Harris’s sparrows have a varied diet that changes depending on the season and habitat.
Breeding Season Diet
During the breeding season, which lasts from late May to early August, Harris’s sparrows eat primarily insects and other invertebrates. Their diet includes:
- Caterpillars
- Moths and butterfly larvae
- Beetles
- Grasshoppers
- Crickets
- Spiders
- Ants
- Aphids
- Other small insects
Insects provide a nutritious source of protein for Harris’s sparrows during the breeding season when energy demands are high due to nesting and raising young. Adults will forage for insects among the shrubs and on the ground, often scratching in the leaf litter to uncover food. They may also occasionally eat small fruits and seeds early in the breeding season.
Winter Diet
Harris’s sparrows shift to eating mainly seeds and grains during the winter months. Important winter foods include:
- Seeds from grasses and sedges
- Waste grain such as corn, wheat, milo
- Seeds from weeds and shrubs
- Buds and catkins from trees and shrubs
- Berries from sumac, poison ivy, Virginia creeper
Harris’s sparrows forage for seeds and grains on the ground, in fields, along roadsides, and under bird feeders. They use their cone-shaped bill to crack open seeds and expose the inner contents. During harsh winter weather, waste grain from agricultural areas can provide an abundant source of food. Harris’s sparrows may also visit feeding stations stocked with mixed birdseed.
Spring and Fall Diet
During migration in the spring and fall, Harris’s sparrows stopover in a variety of habitats across North America. Their diet during migration consists of:
- Insects such as beetles, caterpillars, grasshoppers
- Seeds and grains
- Fruits from trees, shrubs, vines
- Nectar from flowers
The combination of insect protein and plant foods provides the energy and nutrients Harris’s sparrows need to fuel their long migrations between breeding and wintering grounds. They forage in grasslands, shrublands, woodland edges, backyards, and gardens during migration.
Adaptations for Feeding
Harris’s sparrows have several key adaptations that help them find and handle food:
- Cone-shaped bill – Allows them to crack and hull seeds
- Scratching feet – Rake through leaf litter to uncover insects and seeds
- Wide lateral vision – Lets them scan the ground while foraging
- Sensitive bill tip – Help locate seeds and insects in substrate
Additionally, Harris’s sparrows often forage in flocks during migration and winter. Foraging in groups may reduce time spent being vigilant for predators, increase the chance of finding patchy food sources, and provide information about productive feeding locations.
Diet Differences by Age
The diet of Harris’s sparrows differs somewhat between ages:
- Nestlings: Fed mostly insects, spiders, and some seeds by parents
- Fledglings: Still rely on parents for food at first but soon begin foraging on their own. Eat insects, spiders, seeds.
- Juveniles: Resemble adults but with a more insect-heavy diet after leaving breeding grounds.
- Adults: The most versatile diet, switching between insects, seeds, grains, and fruits depending on season and habitat.
The protein-rich insect diet allows young Harris’s sparrows to grow and develop properly. As they mature, their diet shifts to more plant material and closely matches the seasonal patterns of adults.
Preferred Habitats for Feeding
Harris’s sparrows use a range of habitats when searching for food:
- Breeding grounds: Forest openings, shrublands, bogs, fens
- Migration: Backyards, parks, woodland edges, shrublands, marshes, fields
- Wintering grounds: Grasslands, agricultural areas, shrublands, backyards
On their wintering grounds, Harris’s sparrows are often associated with hedgerows, shrubs, and brushy cover. These habitats provide both protective cover and abundant food in the form of seeds, berries, and buds. During migration, Harris’s sparrows are flexible and will stop in any habitat that can provide adequate food resources.
Foods to Attract Harris’s Sparrows
To attract Harris’s sparrows to your yard, try offering these food sources:
- Seeds: Black oil sunflower, nyjer, millet, cracked corn
- Fruits: Raisins, currants, apple chunks
- Suet: High calorie meat-based suet
- Mealworms: High in protein
Harris’s sparrows prefer feeding on or near the ground, so use low platform feeders or scatter seeds directly on the ground. Place feeders near brushy cover for protection from predators. Offering a variety of food types will appeal to Harris’s sparrows with differing nutritional needs throughout the winter.
Important Food Resources by Season
The key food resources used by Harris’s sparrows change throughout the year:
Breeding Season
- Caterpillars and moth larvae
- Beetles, ants, wasps
- Spiders and aphids
- Fruits and buds
Fall Migration
- Insect larvae and eggs
- Seeds from grasses and forbs
- Fruits from shrubs and vines
- Nectar from wildflowers
Winter
- Waste grain (corn, wheat, milo)
- Weed seeds
- Seeds and catkins from trees/shrubs
- Berries from poison ivy, sumac, vines
Spring Migration
- Insects and larva
- Seeds from grasses and forbs
- Buds from shrubs and trees
- Spilled grain in fields
The wide variety of foods eaten by Harris’s sparrows allows them to thrive across a diversity of habitats and seasonal conditions throughout their annual cycle.
Typical Food Consumption
The amount of food Harris’s sparrows consume each day varies by factors like age, season, and weather conditions. Some estimates include:
- Nestlings can be fed 25-40 times per hour as they grow.
- Adults may consume 15-20% of body mass daily.
- Up to 60% of winter day spent foraging.
- May increase intake before migration to add fat.
- Cold snaps increase energy demand and consumption.
Harris’s sparrows spend more time feeding during winter to meet energy needs. Food availability is lower and they require more calories to maintain body heat. Peak consumption occurs right before migration as they build up fat reserves for the journey.
Foraging Behaviors
Harris’s sparrows exhibit particular foraging behaviors and strategies:
- Forage on ground in open areas near protective cover
- Scratch leaf litter with feet to uncover food
- Make short flights from shrubs down to ground to catch insects
- Form large flocks in winter to cover more ground while feeding
- Join mixed flocks during migration to take advantage of local food sources
- Visit feeders but prefer platform or ground feeders
- Consume grit such as sand to help grind food in gizzard
- Exhibit frantic feeding behavior before migration or cold weather
Harris’s sparrows use their behavioral flexibility and social foraging tendencies to take advantage of a wide array of food resources across many different habitats throughout the year.
Impacts of Diet on Survival and Reproduction
Access to sufficient food resources impacts Harris’s sparrow survival and reproduction in several key ways:
- Chicks fed adequate insects grow faster and have higher survival.
- Adults need proper nutrition for successful migration and winter survival.
- Pre-migration weight gain is correlated with higher migration success.
- Good winter food supplies result in earlier nesting and breeding.
- Higher overwinter survival if sufficient calories are available.
When food is scarce due to drought, crop failure, or habitat loss, Harris’s sparrow fitness declines. Providing adequate nutrition year-round is therefore critical for maintaining healthy populations of this species.
Role of Insects in Diet
Insects, spiders, and other invertebrates play an essential role in the Harris’s sparrow’s diet by:
- Providing abundant protein for growth and development.
- Allowing adults to meet the high energy demands of breeding.
- Enabling young to fledge at proper weights.
- Supplying crucial nutrients not found in plant material.
- Providing food when seeds/grains are scarce.
Insect availability may influence habitat quality for breeding Harris’s sparrows. Declines in insect populations due to pesticides, habitat loss, and climate change could therefore negatively impact Harris’s sparrow reproduction and chick survival.
Impacts of Supplemental Feeding
Supplemental feeding of Harris’s sparrows during migration or winter may impact them by:
- Allowing them to winter further north if food is adequate.
- Potentially increasing overwinter survival and body condition.
- Providing buffer against crop failures or habitat loss.
- Supporting higher breeding productivity.
- Concentrating birds and increasing disease transmission risk.
- Creating competition with other species at feeders.
Feeding Harris’s sparrows may benefit populations, but may also have unintended consequences. More research is needed to better understand these complex interactions.
Effects of Climate Change
Climate change may affect Harris’s sparrow diet and nutrition by:
- Altering plant communities and food availability.
- Changing insect abundance, emergence, and geographic ranges.
- Increasing frequency or intensity of droughts.
- Causing mismatches between food supply and breeding chronology.
- Allowing range expansions of competitor species.
A warming climate will likely cause both geographic and seasonal shifts in food resources for Harris’s sparrows. Their ability to adapt will depend on habitat availability and maintaining adequate nutrition.
Conclusion
Harris’s sparrows are unique among sparrows for their relatively varied diet and use of diverse foraging habitats across North America. Their complex annual cycle, from arctic breeding grounds to central plains wintering areas, relies on adequate food resources being available during each phase. Insects are particularly important for Harris’s sparrow reproduction and survival. Changes to food supplies from climate change, habitat loss, and other factors could negatively impact Harris’s sparrow populations. Providing suitable breeding habitat with abundant insects and high-energy foods from fall through spring will be key for the continued prosperity of these remarkable migratory songbirds.
