Warblers are small songbirds that belong to the family Parulidae. There are around 115-120 recognized species of warblers worldwide. They are found throughout North America, particularly during migration periods. Warblers occupy a variety of habitats and eat a diverse array of foods depending on the species.
Quick Answer
Yes, some species of warblers do eat seeds as part of their diet, particularly in the winter months when other food sources are scarce. However, they are primarily insectivorous, feeding mainly on insects and spiders. The consumption of seeds varies by species, with some warblers being more prone to eating seeds than others when insect prey is unavailable.
Warbler Diets
In general, warblers are considered primarily insectivorous, feeding mainly on insects and spiders which provide them with protein. During the breeding season in spring and summer when insects are abundant, insects and spiders make up the vast majority of their diet. Some common insect prey include caterpillars, moths, beetles, flies, ants, bees, wasps, and dragonflies.
However, warblers are opportunistic foragers and will supplement their diet with other food sources depending on seasonal availability. These alternative foods can include fruit, nectar, tree sap, and seeds. The consumption of seeds tends to increase during the fall migration and winter months when insect numbers decline. Unlike insects, seeds provide carbohydrates and fat, which are especially important energy sources for migrating and overwintering birds.
Seed-Eating Warblers
Several warbler species are more prone to eating seeds than others:
- Pine warblers – Eat large amounts of seed from conifers and other trees
- Palm warblers – Will eat bayberry fruits and seeds
- Yellow-rumped warblers – Consume wax myrtle and bayberry fruits in winter
- Common yellowthroats – May forage on grass and sedge seeds
- Ovenbirds – Include moderate amounts of seeds in their winter diet
Other warblers like prairie warblers, orange-crowned warblers, and Connecticut warblers may occasionally eat small amounts of seeds as well. The seeds are typically swallowed whole.
Fruits and Berry Consumption
In addition to seeds, many warblers will supplement their diet with fruits and berries when available. The most common fruit-eating warblers include:
- American redstarts
- Cape May warblers
- Tennessee warblers
- Bay-breasted warblers
- Blackburnian warblers
These fruits provide an important source of carbohydrates for migratory warblers in particular. Some preferred fruits include dogwood, viburnum, sumac, Virginia creeper, and pokeweed. Berry consumption tends to spike in late summer and fall when ripe berries become abundantly available.
Foraging Behaviors
Warblers employ a variety of foraging techniques and strategies when searching for food:
- Gleaning – Carefully picking insects, spiders, or fruit off of leaves, branches, and trunks of trees and shrubs.
- Hover-gleaning – Gleaning while hovering briefly in place.
- Hawking – Catching insects in mid-air.
- Probing – Inserting their bills into crevices and holes in search of hidden arthropods.
- Sallying – Flying out from a perch to catch prey and returning.
When foraging on the ground for seeds, warblers will scratch through litter searching for fallen seeds. Their thin pointed bills are well-adapted for picking up small seeds and insects.
Seed Preferences
The types of seeds consumed by warblers varies by habitat and season. Some commonly eaten seeds include:
- Pine seeds
- Maple seeds
- Birch seeds
- Grass seeds
- Ragweed seeds
- Sedge/rush seeds
- Bayberry fruits
- Wax myrtle fruits
- Dogwood fruits
- Sumac seeds
In general, warblers appear to prefer smaller soft seeds that are more easily swallowed. Harder seeds from plants like honey locust are avoided. The high fat content of bayberry and wax myrtle fruits make them attractive for migrating birds needing to build up fat reserves.
Implications for Bird Feeders
Since many warblers do consume seeds, especially in winter, providing bird feeders with warbler-friendly seeds can help attract them to your yard. Some useful seeds to offer include:
- Nyjer thistle
- Safflower
- Fine sunflower chips
- Cracked corn
- Hulled peanuts
- Suet
These small seeds are easy for warblers to handle. Use mesh feeders that allow warblers to cling while feeding. Placing feeders near shrubs and trees provides landing spots. Be sure to position feeders out of reach of cats.
Conclusions
In summary, the majority of warblers are insectivorous, feeding mainly on insects and spiders. However, many species supplement their diet with seeds, particularly during fall and winter when insect numbers decline. Seed-eating tends to be more common among certain warbler species like pine warblers and palm warblers. Preferred seeds are often small and soft like birch, maple, and grass seeds. Providing warbler-friendly seeds in mesh feeders can help attract them to backyards.
