American tree sparrows are small songbirds that are found across North America. They are part of the sparrow family and get their name from their habit of perching and nesting in trees. American tree sparrows have a varied diet that changes depending on the season and habitat. Here is an overview of what these birds eat.
Insects and Arachnids
Insects and arachnids like spiders make up the bulk of the American tree sparrow’s diet, especially during spring and summer. They will eat beetles, caterpillars, ants, grasshoppers, crickets, mosquitoes, flies, moths, spiders, and more. This provides the protein and fat that these birds need for breeding and raising young.
American tree sparrows forage primarily on the ground for insects. They use their conical bills to pick insects off of plants or probe into crevices. During summer, they may also catch flying insects while perched on branches. Parents will feed captured insects to their nestlings.
Favorite Insect Prey
Some of the American tree sparrow’s favorite insect prey includes:
- Beetles
- Caterpillars
- Grasshoppers
- Crickets
- Ants
- Spiders
Beetles are a particularly important part of their diet. American tree sparrows will eat beetle adults, larvae, and eggs. Common species include weevils, longhorn beetles, leaf beetles, and bark beetles.
Seeds and Grains
American tree sparrows switch their diet to seeds and grains during fall and winter. This includes the seeds of wild grasses, sedges, agricultural grains like wheat and oats, and the fruit/seeds of shrubs and trees.
They forage for seeds on the ground, plucking them from seed heads or grass stems. Bird feeders stocked with mixed birdseed are readily visited by American tree sparrows. Backyard birders can easily attract them with millet, cracked corn, and sunflower seeds.
Favorite Seed Foods
Some of the American tree sparrow’s favorite seeds/grains include:
- Grass and sedge seeds
- Wheat
- Oats
- Millet
- Ragweed
- Sunflower
Being ground foragers, American tree sparrows prefer small seeds that have fallen to the ground over large seeds that remain on plants. Granivory provides the carbohydrates and fat that help them survive cold winters.
Fruits and Berries
American tree sparrows also consume the fruits and berries of certain trees, shrubs, and vines. They especially target native plants like dogwoods, viburnums, sumacs, and wild grapes. The fruits provide sugars and carbs to fuel their active metabolisms.
Fruits that they particularly relish include:
- Crabapples
- Sumac berries
- Dogwood berries
- Grapes
- Bayberries
- Rose hips
- Bittersweet berries
American tree sparrows eat fruits by plucking them directly off plants with their beaks. They help distribute undigested seeds through their droppings.
Other Foods
On rare occasions, American tree sparrows have been documented eating other types of foods besides insects, seeds, and fruits. These incidental food items include:
- Tree sap – Provide sugars
- Nectar – Also provides sugars
- Suet – Provides fat
- Bird eggs – Provides protein
Saps and nectars are licked up by the sparrows directly from plants. Suet may be eaten if offered at bird feeders. Cases of egg predation are rare and likely opportunistic.
Adaptations for Feeding
American tree sparrows have several key adaptations that allow them to feed on their varied diet:
- Conical beak – Allows them to crack into seeds and probe for insects.
- Strong legs – Lets them scratch and dig through leaf litter for food.
- Perching feet – Helps them grip branches as they pick fruits and seeds.
- Powerful digestion – Can break down diverse foods including hard grains and fruits.
Their conical beak shape is suited for consuming both insects and seeds. The beak can stab and consume soft-bodied insects or crack hard-shelled beetles and seeds. Their legs allow them to hop and scratch along the ground, kicking up insects and uncovering seeds buried in leaf litter.
Differences by Season
American tree sparrows shift their diets between the seasons:
Season | Primary Foods |
---|---|
Spring | Insects and arachnids |
Summer | Insects |
Fall | Insects, seeds and grains |
Winter | Seeds and grains, fruits |
In spring, their diet is composed almost entirely of insects and spiders as they become active and prepare for breeding. Through summer, they continue feeding nestlings protein-rich insects to support growth. In fall, they switch to more seeds and grains as insect numbers decline. By winter, their diet is dominated by plant-based foods in the absence of insects.
Differences by Habitat
American tree sparrows inhabit a diversity of habitats across North America. The foods they eat can vary somewhat based on habitat:
- Tundra – More roots, leaf buds, berries. Fewer insects.
- Coniferous forest – More conifer seeds. Spruce budworm caterpillars.
- Deciduous forest – Acorns, tree sap, leaf litter insects.
- Grassland – More grass and weed seeds. Grasshoppers.
- Backyards – Feeder seeds, fallen fruits.
For example, tundra-dwelling sparrows eat more tundra-adapted fruits like cranberries and crowberries. Forest-dwelling sparrows consume more tree products. Grassland birds eat more grassland insects and seeds. Backyard visitors take advantage of feeders and ornamental plants.
Do American Tree Sparrows Drink Water?
Yes, American tree sparrows need to drink fresh water regularly like all birds. During drier parts of the year, they will seek out and drink from small freshwater pools, streams, ponds, and other water sources. Birdbaths and water drippers can provide them with needed hydration.
American tree sparrows get most of their moisture from their food during wetter times of year. Succulent fruits and insects provide a lot of dietary water. But they still need to drink water even when their diet is wet, just in smaller amounts supplemented by food moisture.
Do American Tree Sparrows Eat Bird Seed? What Kinds?
American tree sparrows readily eat bird seed, especially during fall and winter when seeds make up a larger part of their diet. They prefer smaller “finch-type” seeds over larger “sunflower-type” seeds since they hull seeds with their conical beaks and lack powerful cracking bills.
Some of the best bird seeds to offer American tree sparrows include:
- Millet
- Cracked corn
- Hulled sunflower chips
- Nyjer
- Safflower
- Peanut chips
- Cracked nuts
- Fine dried mealworms
Mixes containing millet, sunflower chips, corn, and peanuts will be readily eaten. Platform feeders or scattered seed on the ground suits them best since they prefer to pick up fallen seeds.
Do American Tree Sparrows Visit Bird Feeders?
Yes, American tree sparrows are common winter visitors at backyard bird feeders within their range. They prefer platform or tray feeders placed at ground level where they can scratch and pick up spilled seeds. Hopper or tube feeders are visited less often. They may perch briefly to grab seeds, then fly off to eat on the ground.
What Do American Tree Sparrow Babies Eat?
American tree sparrow chicks are fed insects by their parents in the nest. Caterpillars are particularly important, providing lots of protein for growth. The parents may feed over 100 caterpillars to a nest full of noisy chicks in a day. Other insects like beetles, crickets, flies and spiders round out their diet.
As chicks near fledging age around 10-13 days old, parents gradually start providing some seeds and fruits in addition to insects. This helps transition them to the adult diet they will need after leaving the nest. Fledglings follow their parents around and beg loudly for food for several weeks after fledging.
What Do American Tree Sparrows Drink?
American tree sparrows drink fresh water from small pools, puddles, drippers, and bird baths. They are found drinking most frequently during drier parts of the year when their food provides less moisture. The birds utilize their conical beak like a straw to suck up and swallow water.
In wetter seasons, most of their water needs can be met by the moisture content in fresh fruits, juicy insects and green leafy plant foods. But they still periodically drink water to supplement their diet.
Do American Tree Sparrows Eat From Hummingbird Feeders?
American tree sparrows are not frequent visitors to hummingbird feeders. Their conical seed-cracking beaks are not well adapted for licking up nectar. They will sometimes perch briefly on feeders but have difficulty accessing the nectar.
However, during times of extreme food scarcity such as severe winter weather, very hungry American tree sparrows may persistently feed on hummingbird nectar. The high sugar content provides quick energy despite their inefficient nectar-lapping ability. This is rare behavior though and they strongly prefer their natural seed and insect diet.
Do American Tree Sparrows Migrate? How Does Diet Change?
Yes, American tree sparrows are migratory over most of their range. They breed during summer in Canada and Alaska and migrate south to the southern U.S. or Mexico for winter.
Their diet changes with seasonal abundance. During summer breeding grounds, insects make up the majority of their diet. After breeding season, they switch to eating more seeds and grains before migration. In their winter grounds, they eat a mix of seeds and fruits, supplemented by insects in warmer areas.
Access to food influences their migration timing. Early cold snaps with food scarcity prompt earlier fall migration. Mild winters with adequate food allow them to delay spring migration. These dietary needs influence their migratory habits.
What Determines American Tree Sparrow Migration Patterns?
Several factors influence American tree sparrow migration patterns and timing, including:
- Food availability – Lack of insects and seeds triggers earlier fall migration. Adequate food may delay spring migration.
- Weather – Early winter storms and cold cause earlier fall migration. Mild winters delay spring migration.
- Photoperiod – Decreasing daylight in fall, increasing daylight in spring impact hormonal changes.
- Age – Younger birds often migrate later in fall and earlier in spring than adults.
Food abundance and weather are the most important factors driving migration timing. Photoperiod and age also influence migration, but are secondary factors. If food is scarce, they will migrate regardless of daylight cues.Young birds may be forced to migrate later and return sooner due to lack of dominant feeding areas.
Do American Tree Sparrows Store Food? What Kinds?
American tree sparrows do not actively hoard or cache significant food stores. However, they may incidentally leave uneaten seeds and fruits beneath plants, shrubs, and grass stalks simply by dropping extras while feeding.
These incidental small seed and fruit caches are not purposefully stored for later use. The sparrows may opportunistically eat them later while foraging in the same area. But their larder-hoarding instinct is weaker compared to other seed-eating birds.
Some of the foods they may incidentally cache while feeding include:
- Grass and weed seeds
- Fallen berries beneath shrubs
- Cracked seeds or hulls
- Partially-eaten fruits
These incidental caches only make up a tiny fraction of their food though. American tree sparrows predominantly forage actively day-by-day rather than relying on stored food reserves.
Where do American Tree Sparrows Forage?
American tree sparrows forage for food in the following habitats:
- Backyards – Under bushes, near feeders
- Fields – Along edges, fence lines
- Roadsides – On shoulders, medians
- Forest edges – Where forests meet fields
- Wetlands – Around muddy pond edges
They prefer weedy areas with a mix of grass, shrubs, and bare ground. This provides both cover and easy access to seeds and insects. Backyards offer prime foraging habitat when stocked with native plants.
Foraging Behavior
When foraging, American tree sparrows exhibit some typical behaviors:
- Hopping along the ground to kick up seeds
- Scratching backwards with feet to expose insects and seeds
- Perching briefly on plants or shrubs to pick fruits/seeds
- Low, short flights between foraging patches
Their ground-based foraging makes them vulnerable to predators. They stay alert and flee quickly into cover when threatened. American tree sparrows rarely forage out in open exposed areas for long.
Conclusion
In summary, American tree sparrows are dietary generalists adapted for eating insects, seeds, and fruits. Their diet shifts seasonally, prioritizing insect prey in summer and plant foods in winter. Tree sparrows forage primarily on the ground, scratching for food across diverse open habitats with a mix of bare ground and low vegetation. Understanding their dietary needs and foraging strategies provides insights into their life history.