The yellow-bellied flycatcher is a small migratory songbird that breeds in the boreal forests of Canada and the northern United States and winters in the tropical forests of Central and South America. Here is an overview of the yellow-bellied flycatcher’s diet and feeding habits.
Insects and Other Invertebrates
Yellow-bellied flycatchers are insectivores, meaning insects and other invertebrates make up the majority of their diet. During the breeding season, they mainly eat flying insects that they catch on the wing by sallying out from an open perch. Their main prey items include:
- Flies
- Bees
- Wasps
- Butterflies and moths
- Beetles
- Caterpillars
- Spiders
- Dragonflies
Research studies that have analyzed the stomach contents of yellow-bellied flycatchers have found that flies from the families Tipulidae (crane flies), Muscidae (house flies) and Empididae (dance flies) make up around 60-80% of their diet. They also eat a substantial number of bees and wasps from the families Apidae and Vespidae.
On their wintering grounds in Central and South America, yellow-bellied flycatchers continue to eat mainly insects. Some studies have found that the bulk of their diet there consists of different species of flies, beetles, moths, ants, and caterpillars.
Feeding Habits and Hunting Techniques
Yellow-bellied flycatchers have a few characteristic feeding behaviors and insect hunting techniques:
- They often perch on an open branch or pole and sally out to catch passing insects, returning to the same perch.
- They sometimes hover briefly to grab insects while hunting on the wing.
- They move actively through trees and shrubs, picking insects off leaves and branches as they go.
- They may sometimes catch insects on the ground by fluttering down from a perch.
Their ability to hunt insects on the wing gives yellow-bellied flycatchers an advantage over species that rely more on gleaning insects from foliage. It allows them to exploit the abundance of flying insects that are often found at higher elevations in the upper canopy of coniferous forests where they breed.
Spiders and Fruit
Although insects make up the majority of their diet, yellow-bellied flycatchers are somewhat opportunistic and will occasionally eat other prey. Two other food sources they are known to consume are:
- Spiders – Yellow-bellied flycatchers will sometimes eat spiders they encounter in their habitat. One study found spider remains in about 15% of flycatcher stomachs examined.
- Fruit – In their tropical wintering grounds, yellow-bellied flycatchers occasionally eat small berries and fruits. Some field observations have recorded them eating things like figs, bananas and mistletoe berries.
However, these food items comprise a very small percentage of the overall diet. Insects and other invertebrates make up more than 90% of what yellow-bellied flycatchers eat in most circumstances.
Feeding Behavior by Season
Yellow-bellied flycatchers exhibit some seasonal differences in their feeding habits:
Breeding Season
During the breeding season from May to August, yellow-bellied flycatchers feed more actively to meet the high energy demands of breeding, nesting and feeding their young. They primarily eat insects caught on the wing, consuming a wide variety of flying insects that become abundant in the northern forests in summer.
Migration
On migration between their breeding and wintering grounds, yellow-bellied flycatchers stopover in various wooded habitats. There they replenish their energy by gleaning insects and spiders from the leaves, branches and trunks of trees and shrubs. They eat a wider variety of prey during migration than they do on the breeding grounds.
Wintering Grounds
On their tropical wintering grounds, yellow-bellied flycatchers spend more time gleaning insects from foliage. This includes prey like caterpillars that are less common on the breeding grounds. They also eat more fruit during winter when insect numbers decline.
Adaptations for Feeding
Yellow-bellied flycatchers have several physical and behavioral adaptations that help them find and catch insect prey:
Large Eyes
They have large, prominent eyes placed high on their heads. This gives them excellent binocular vision to spot insects while hunting on the wing.
Wide Gape
They have a large, wide gape bordered by stiff rictal bristles. This helps them scoop insects out of the air efficiently in mid-flight.
Swift, Acrobatic Flight
They are agile, nimble fliers capable of aerial maneuvers to catch insects. Their slender, streamlined body shape reduces air resistance while flying.
Perch-Hunting
Their perch-hunting strategy allows them to scan for passing insects from an open vantage point before flying out to grab them.
| Season | Diet and Feeding Habits |
|---|---|
| Breeding Season |
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| Migration |
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| Wintering Grounds |
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Habitat and Range Affect Diet
The specific types of insects and other prey eaten by yellow-bellied flycatchers varies across their wide breeding and wintering range based on habitat and local insect availability. However, they maintain their primarily insectivorous diet across their range.
Breeding Grounds
Across different parts of their breeding range in Canada and the northern U.S., the specific insect composition of yellow-bellied flycatcher diets can shift depending on habitat. For example, one study found flycatchers eating more flies in mature coniferous forests but more beetles, bees and ants in younger mixed forests.
Wintering Grounds
On their wintering grounds spanning Mexico, Central America and northern South America, yellow-bellied flycatchers inhabit both lowland rainforests and high-elevation cloud forests. But their diet remains dominated by insects like flies, moths, beetles and ants in both environments.
Comparison to Related Species
The yellow-bellied flycatcher’s diet is similar to some other closely related flycatcher species:
Alder Flycatcher
The alder flycatcher is the yellow-bellied flycatcher’s closest relative. It eats a very similar diet dominated by flying insects like flies, bees, wasps and butterflies. Alder flycatchers may eat fewer spiders and less fruit though.
Willow Flycatcher
Willow flycatchers eat mostly flying insects augmented with some spiders. Their prey breakdown seems very similar to yellow-bellied flycatchers.
Least Flycatcher
Least flycatchers are also highly insectivorous, but may not eat quite as many bees and wasps as yellow-bellied flycatchers. They also occasionally eat seeds in winter.
Conclusion
In summary, the yellow-bellied flycatcher is a voracious insectivore, with insects composing over 90% of its diet. Flies, bees, wasps, moths, beetles and caterpillars are their main prey. They use aerial sallying maneuvers to catch insects on the wing. Spiders and fruit are minor supplementary food sources. Their specific prey species varies across their breeding and wintering range, but insects remain the staple food. Their insect-dominated diet is similar to related flycatcher species.
