Birds in the family Tyrannidae are commonly known as tyrant flycatchers or simply flycatchers. There are over 400 species in this diverse family found throughout the Americas. But why are they called flycatchers? The answer lies in their feeding behavior.
Flycatchers get their name from the specialized techniques they use to catch insects on the wing. They will dart out from a perch to snap up flying insects, often returning to the same perch afterward. This behavior gave rise to their descriptive name.
Feeding Techniques
Flycatchers have evolved a number of strategies to effectively catch insects while in flight:
Sit-and-Wait Hunting
Many flycatcher species use a sit-and-wait hunting technique. They will perch on a branch or wire and scan the surroundings, waiting for an insect to fly by. When they spot prey, they launch themselves into the air and snatch the insect with precision timing. The flycatcher may return to the same perch or a new one nearby. This allows them to conserve energy while hunting.
Aerial Hawking
Some flycatchers are more active hunters. They use an aerial hawking technique to pursue insects while in flight. The flycatcher will sally forth after flying insects, chasing them through the air and performing acrobatic twists and turns to keep up. This takes greater energy but allows the bird to hunt while on the move.
Gleaning
In addition to catching insects on the wing, many flycatchers will supplement their diet through gleaning. This means they pick stationary or slow-moving prey from leaves, branches, or the ground. Gleaning provides a more reliable food source to balance out the greater effort required for aerial flycatching.
Specialized Adaptations
Flycatchers have several physical adaptations that aid their insect-catching abilities:
Large Eyes and Head
Most flycatchers have disproportionally large eyes and broad, flat heads. This provides them with excellent vision suited to detecting fast-moving prey at a distance. Their wide field of view and depth perception help target insects while in flight.
Gaping Mouth
Flycatchers have a large, wide gape that allows them to snatch insects from the air with speed and accuracy. They also have stiff rictal bristles around the base of the beak, which may help protect the eyes or funnel prey into the mouth.
Short, Pointed Beak
The beaks of flycatchers are relatively short but pointed, which gives them precise aim and timing to seize insects on the wing. The beaks often have a small hook at the end to ensure a firm grip.
Swift, Agile Flight
Flycatchers have compact, muscular bodies and long, tapered wings. This morphology allows them to perform quick takeoffs, rapid aerial maneuvers, and swift pursuit of flying insects.
Reaction Speed and Coordination
In order to effectively catch insects in midair, flycatchers require incredible reaction time and precise coordination. Here are some of the feats flycatchers are capable of:
– Detecting and pursuing an insect in a fraction of a second. Their eyes and brains process visual information extremely rapidly.
– Calculating the trajectory of flying prey and predicting exactly where to intercept it.
– Making complex in-flight adjustments to account for wind speed and direction.
– Judging distances and relative motion with pinpoint accuracy.
– Timing their takeoff and midair movements with split-second precision.
– Snatching insects in their beak at just the right instant without slowing down.
Catching insects on the wing requires processing a huge amount of visual data and making constant micro-adjustments, all at high speeds. The flycatchers’ physiology and brains have evolved to meet these demands.
Diet and Prey
The types of flying insects that flycatchers prey upon depends on their habitat and location, but some common foods include:
| Bees | Butterflies |
| Wasps | Moths |
| Flies | Beetles |
| Dragonflies | Grasshoppers |
| Cicadas | Ants |
Various species may show preferences for certain insects depending on availability. Some flycatchers that live in dense forests focus on capturing moths and dragonflies. Open habitat species tend to target bees, wasps, beetles, grasshoppers, and flies.
Catching insects on the wing provides flycatchers with a nutritious food source. Insects supply important proteins as well as other nutrients like fats, vitamins, and minerals.
Foraging Behavior
Flycatchers often have specialized foraging behaviors and strategies when catching insects:
– Many species will return to favorite perches, defending a hunting territory full of flying insects.
– Some cooperatively hunt in family groups, taking turns catching insects flushed by other birds.
– Tropical species follow swarms of army ants, preying on insects fleeing from the ants.
– During migratory stopovers, flycatchers opportunistically gorge on abundant insects to refuel.
– Resident species may make seasonal adjustments, targeting the most plentiful insects in their habitat.
This adaptability and variety of hunting techniques allows flycatchers to take advantage of ephemeral food sources.
Unique Hunting Methods
While most flycatchers catch insects on the wing, some species have developed alternative hunting techniques:
Berry Eating
The brown-crested flycatcher from South America relies heavily on wild berries. Up to two-thirds of its diet can consist of berries, an unusual strategy among tyrant flycatchers. It uses its aerial sallying technique to pluck berries while hovering.
Bark Foraging
The black phoebe of North America forages along streams, picking insects directly from tree bark. It runs along vertical surfaces and probes into crevices much like a nuthatch or creeper. Only about one-third of its prey is caught on the wing.
Ground Pouncing
The vermilion flycatcher sometimes drops down from its perch onto the ground to ambush large insects like grasshoppers and crickets. It displays greater agility hunting on the ground compared to other flycatcher species.
Stalking
The sulphur-bellied flycatcher has a more patient, stealthy approach to hunting. It slowly works its way through the midstory of the forest, deliberately checking leaves and branches for camouflaged prey.
Notable Examples of Flycatchers
While there are hundreds of species of tyrant flycatchers, below are a few noteworthy examples:
Scissor-tailed Flycatcher
This iconic species of the American Southwest is named for its extraordinarily long, forked tail, which can exceed 10 inches. It is a graceful aerialist, sometimes feeding on insects stirred up by wildfires.
Variegated Flycatcher
Distinctively patterned with streaks of black, white, and rufous, this species performs dramatic aerial displays during courtship. It migrates long distances from South America to Mexico each year.
Flame-crowned Flowerpiercer
As the name suggests, this tropical flycatcher has a bright reddish-orange crown patch. It gets nectar by piercing the base of flowers with its sharp bill. It’s the only flycatcher known to feed on nectar.
Pied Water-Tyrant
Found near rivers and streams in South America, this aptly named species forages by sallying out over water to catch aquatic insects on the wing. It has unusually large feet to enable perching on floating vegetation.
Evolution of Flycatching Behavior
The specialized flycatching behavior seen in the Tyrannidae likely evolved as both a response to competition and an adaptation to take advantage of an abundant food source. Here is how the behavior may have developed:
Competition with Other Insect-Eating Birds
With many bird families feasting on insects, flycatchers faced competition for prey. Developing a swift aerial technique to target elusive flying insects allowed them to exploit an underutilized niche.
Shift from Waiting to Pursuit Hunting
Ancestral flycatchers were likely foliage gleaners that opportunistically sallied for insects. Over time, some lineages became more specialized in active aerial pursuit of insects.
Refinement of Flight Performance
Natural selection would have favored anatomical adaptations allowing flycatchers to catch insects with greater speed, agility, and accuracy while airborne.
Enhancement of Visual Acuity
Keen eyesight became critical for detecting and tracking small, fast-moving prey. Flycatchers evolved larger eyes and expanded visual processing power.
Development of Aerially-Hawking Species Complexes
Closely related flycatcher species diverged to take advantage of different prey in separate habitats, leading to diverse hawking specialists.
The incredible aerial skills of modern flycatchers are really a testament to millions of years of evolution honing their insect-catching abilities.
Threats and Conservation
While flycatchers as a family remain widespread and fairly common, some specific species face elevated threats:
Habitat Loss
Destruction of forests and meadows for agriculture, development, and logging has caused declines in many flycatcher populations, especially endemic island species.
Nest Parasitism
Brood parasites like brown-headed cowbirds lay eggs in flycatcher nests, reducing reproductive success. This has impacted species like the southwestern willow flycatcher.
Insect Declines
Pesticides, climate change, invasive species, and other factors have led to dwindling aerial insect numbers in some regions, threatening insectivorous flycatchers.
Collision Mortality
Migratory flycatchers in North America face increasing hazards from collisions with buildings, towers, and vehicles during nocturnal travel.
To protect vulnerable species, conservation measures like safeguarding migration stopover sites, controlling cowbirds, and preserving large intact habitats can be beneficial. But reversing broader insect population declines may be key for the long-term preservation of flycatchers. Their specialized aerial hunting lifestyle relies on abundant flying insect prey.
Conclusion
In summary, flycatchers get their common name directly from their expert ability to catch insects in midair. A combination of anatomical adaptations and split-second reaction times allow them to successfully hunt on the wing. Flycatching requires intense visual focus, rapid response, and precise coordination. While flycatching behavior likely evolved to help tyrant flycatchers exploit an abundant aerial food source, some species have developed unique alternative hunting techniques. Looking ahead, maintenance of healthy insect populations will be integral for the persistence of these acrobatic birds. Their aerial skills provide a glimpse into nature’s ingenuity.
