Many species of birds are specially adapted to catching insects in mid-air. This allows them to take advantage of the abundant insect populations that fly around during warmer weather. Birds that are aerial insectivores have developed visual, morphological, and behavioral traits that make them skilled bug catchers.
Insects provide an important source of protein for many bird species. Being able to pluck insects out of the air gives certain bird species access to food that is not available to other animals. Additionally, catching flying insects requires special skills that only some types of birds possess.
Traits that Help Birds Catch Insects
Birds that specialize in catching insects on the wing have evolved features that facilitate this behavior:
- Excellent eyesight – Aerial insect eaters have visual acuity that allows them to see small, fast moving insects.
- Wide gape – These birds have a large mouth relative to their head size which enhances their ability to scoop up insects.
- Sensitive bill – The bill has tactile receptors that help detect the presence of insects.
- Swift flight – They are able to accelerate and change direction rapidly in pursuit of prey.
- Maneuverable wings – Their wings allow for agile control of speed and direction.
Additionally, aerial insectivores use specific hunting techniques such as sallying, hovering, and flycatching. Their bodies are often adapted for these behaviors.
Common Aerial Insectivores
Some of the most common types of birds that catch insects on the wing include:
Swallows
Swallows are agile, slender birds with long, pointed wings and tiny bills that are perfect for snatching up insects. The stiff feather shafts of their wings add strength and maneuverability. Swallows capture flying insects using sallying and flycatching techniques. They gather in large flocks when insects are abundant.
There are around 90 species of swallows including:
- Barn swallow
- Tree swallow
- Bank swallow
- Cliff swallow
Swifts
Swifts are related to swallows and share many of the same adaptations for catching airborne insects. With their swept-back wings and streamlined bodies, swifts are fast, agile fliers. They feed exclusively on insects caught on the wing.
Some common swifts are:
- Chimney swift
- Common swift
- White-throated swift
- Fork-tailed swift
Flycatchers
Flycatchers are passerines with over 300 species worldwide. While flycatchers occasionally eat fruit, seeds, or nectar, they mainly feed on insects which they capture mid-flight. They have quick reflexes and excellent eyesight. Flycatchers use perches as observation posts for spotting insect prey.
Well-known flycatchers include:
- Eastern phoebe
- Western kingbird
- Eastern kingbird
- Gray kingbird
Nighthawks
As their name indicates, nighthawks hunt flying insects from dusk to dawn. Long, pointed wings give them a graceful flight pattern with quick dodges and dives. Their huge mouth extends back past their eyes making it easier to catch prey.
Some nighthawk species are:
- Common nighthawk
- Antillean nighthawk
- Common pauraque
- Lesser nighthawk
Chickadees
While chickadees are not as specialized as swallows and swifts, they do occasionally capture insects mid-flight, especially to feed their young. Chickadees are nimble acrobats that can hang upside down and hover while snatching up flying insects.
Chickadee species in North America include:
- Black-capped chickadee
- Boreal chickadee
- Carolina chickadee
Terns and Skimmers
These coastal bird species use aerial hunting to catch fish and marine invertebrates. With their streamlined body and long, narrow wings they plunge dive at high speeds to snatch up prey either from the water surface or in mid-air.
Examples include:
- Common tern
- Forster’s tern
- Black skimmer
Hunting Strategies
Specialized insect-catching birds use various techniques to hunt on the wing:
Sallying
Sallying involves waiting on an exposed perch and flying out to catch insects before returning to the perch. Flycatchers and swallows use this strategy.
Hawking
Hawking is catching insects while in continuous flight. Swifts and nighthawks cruise through the air with their mouths open to scoop up insects.
Hovering
Hummingbirds and chickadees can hover in place briefly while grabbing insects before darting off. Their rapid wing beats allow them to remain nearly motionless in the air.
Flycatching
Flycatching is making aerial attacks on insects from a perch. Kingbirds and phoebes use this method. They return to the same perch repeatedly between sorties.
Why Eat Flying Insects?
Switching to catch insects in flight offers birds several advantages:
- Abundant food source – Aerial insects provide a huge amount of potential food.
- Reduced competition – Few species can take advantage of mid-air food sources.
- High protein – Insects are a nutritious source of protein for breeding birds.
- Easier work – No need to dig in soil or vegetation for hidden insects.
For species that master it, insect hawking unlocks an exceptional buffet of readily available food. It allows birds to target locations and seasons with the thickest swarms of insects.
Challenges of Catching Insects on the Wing
Plucking tiny insects out of the air demands specialized skills and physiology:
- Speedy flight – Birds need enough speed and stamina to keep up with fast-moving insects.
- Sharp vision – Spotting and tracking tiny insects requires excellent eyesight.
- Quick reflexes – Lightning fast reflexes help birds snap up insects.
- Flexible wings – Maneuverable wings allow aerial twisting and turning.
- Large mouth – A wide gape increases chances of trapping insects.
Catching insects on the wing takes impeccable timing and coordination. The behavioral, anatomical, and sensory adaptations of aerial insectivores allow them to thrive in this challenging niche.
Differences Between Perch and Aerial Hunting
Bird species that catch insects while perched rather than during sustained flight must use a different set of strategies and adaptations:
| Perch Hunting Birds | Aerial Insectivores |
|---|---|
| Search for food from an observation post | Actively fly through swarms of insects |
| Make quick sallies out from perch | Catch prey continuously on the wing |
| Return to same perch repeatedly | Remain airborne and cover large areas |
| Sit-and-wait ambush strategy | Cruising strategy |
| Perching requires less energy | Constant flight requires stamina |
The two methods complement each other. Together, they allow a greater diversity of bird species to share the aerial insect resource.
Conclusion
Many birds are supremely adapted for snatching insects out of the air. Specialized traits like quick reflexes, flexible wings, wide gapes, and acute vision allow them to target the abundant food source that flying insects represent. Aerial insectivores include swallows, swifts, flycatchers, nighthawks, and some chickadees. Hunting strategies like sallying, hawking, hovering, and flycatching help them take advantage of seasonal insect hatches. The ability to catch insects on the wing allows certain bird species to thrive by exploiting food that is unavailable to other animals.
