The Golden-winged Warbler is a small songbird found in parts of North America. Measuring just 4-5 inches in length, these birds have a primarily insect-based diet consisting of various bugs, larva, and spiders. Understanding the dietary habits of the Golden-winged Warbler provides insight into their behavior and habitat preferences.
Insects and Arachnids
During the breeding season, Golden-winged Warblers forage amongst the shrubs and saplings of early successional habitats to find food. Their diet consists predominantly of insects and arachnids during this time of year including:
- Beetles
- Caterpillars
- Ants
- Aphids
- Leafhoppers
- Treehoppers
- Lacewings
- Caddisflies
- Dragonflies
- Grasshoppers
- Crickets
- Spiders
Beetles and caterpillars likely make up the largest portion of their diet. Golden-winged Warblers often forage along the undersides of leaves searching for larva and eggs. Their thin pointed bill allows them to grab and feed on a wide variety insects and spiders.
Favorite Prey
Research studies have identified some key prey that are particularly important for Golden-winged Warblers during the breeding season including:
- Beetle larva
- Caterpillars in the moth families Noctuidae and Geometridae
- Spiders in the families Araneidae and Tetragnathidae
Beetle larva are a nutritious and abundant food source. Caterpillars provide a soft bodied prey that nestlings can easily digest. Spider egg sacs offer a concentrated source of protein for adults and young. These preferred insects likely makeup 50% or more of the total prey consumption each day.
Other Foods
While arthropods dominate their diet, Golden-winged Warblers will supplement with other food sources at times including:
- Wild fruits and berries
- Tree sap
- Nectar from flowers
- Seeds from grasses and plants
These foods provide important carbohydrates and nutrients. Late summer and fall diets shift to include more berries and fruits as they become ripe. Sap wells offer quick energy. Nectar and pollen provide protein and fat. Seeds from vegetation help meet dietary needs.
Geographic Differences
Populations in the western United States tend to consume a higher proportion of spiders compared to eastern birds which eat more caterpillars. This is likely driven by habitat differences and prey availability. Parts of the west contain drier, more open shrublands that support more spiders.
Foraging Behavior
Golden-winged Warblers have a very active foraging style as they search for prey. They move quickly through vegetation looking on the undersides of leaves, along branches, and into crevices of bark. This allows them to find hidden larva and insects. They make short fluttering flights to glean prey items. Their thin bill is well-suited for grabbing small insects and spiders.
Foraging Locations
Preferred foraging locations include:
- On the underside of leaves
- Among clusters of dead leaves
- Along the upper branches of saplings
- On tips of vegetation
Low perches in shrubs allow them to attack passing insects. Leaf clusters provide cover for larva. Upper branches offer access to spiders and caterpillars. Vegetation tips hold tasty aphids.
Diet by Season
The diet of Golden-winged Warblers shifts across the seasons as food availability changes. The key times of year impacting their foraging habits include:
Spring Migration
Insects make up almost the entire diet during migration as birds move north to the breeding grounds. Golden-wings stopover in areas with plentiful caterpillars, beetles, and flies to refuel and put on weight for the journey.
Breeding Season
High protein larva and spiders are critical for reproduction and rearing young. Adults carry food back to nests to feed nestlings. Caterpillars and beetle larva allow chicks to grow rapidly.
Molting Period
Late summer diets feature more wild fruits and berries to provide energy for the annual molt. Grass seeds also help meet nutritional needs for feather regrowth. Insects remain important though for protein.
Fall Migration
In preparation for fall migration, birds increase insect consumption again to add fat reserves. Caterpillars and grasshoppers are key prey during this time.
Impact on Population Trends
Changes in insect and spider populations have affected habitat quality for Golden-winged Warblers in some areas. Increased pesticide use has reduced food availability in parts of their breeding range. Land management practices also impact prey populations. Sufficient foraging resources during the nesting period are critical for reproductive success.
Some research suggests that competition with Blue-winged Warblers for food may also be a factor in Golden-wing population declines in the Appalachian region. Both species target larva and caterpillars, creating potential conflicts.
Conclusion
In summary, Golden-winged Warblers rely predominantly on insects and spiders to meet their dietary requirements, especially during spring and summer. Caterpillars, beetles, and spider egg sacs provide essential nutrition for breeding. These food sources directly influence habitat selection, reproductive success, and migratory patterns. Changes in prey populations from pesticides, land management, and competition ultimately impact Golden-wing populations. Ensuring adequate insect and arachnid food sources is key for sustaining Golden-winged Warblers across their breeding range.
