The Common Nighthawk (Chordeiles minor) is a medium-sized nocturnal bird found throughout much of North America. As an insectivorous bird, the Common Nighthawk feeds on a variety of flying insects that are active at night. Understanding the prey species that the Common Nighthawk consumes can provide important insights into their feeding ecology and natural history.
Insects
Insects make up the majority of the Common Nighthawk’s diet. With its large mouth and ability to maneuver adeptly in flight, the Common Nighthawk is well-adapted for catching insects on the wing. Some of the main insect prey consumed by Common Nighthawks include:
- Beetles (Coleoptera)
- Moths (Lepidoptera)
- Flies (Diptera)
- Ants (Hymenoptera)
- Crickets and grasshoppers (Orthoptera)
- Cicadas (Hemiptera)
- Dragonflies and damselflies (Odonata)
Studies that have examined the stomach contents of Common Nighthawks have found a wide diversity of insects represented. Beetles, moths, flies, and ants often constitute over 50% of the diet. One study in Wisconsin found that Scarabaeid beetles and Noctuid moths were the most common prey items. Another study from Saskatchewan found flies and beetles to be the predominant insects eaten.
The types of insects consumed likely vary based on habitat, season, and local insect availability. In the Prairie Pothole Region, dragonflies can be a major component of the diet. Around urban areas, Common Nighthawks may opportunistically forage on pest species attracted to lights and vegetation, including many moth and beetle species.
Beetles
Beetles (Coleoptera) are a very common prey item for Common Nighthawks across their range. Studies show beetles may make up over 25% of their overall insect diet. Ground beetles (Carabidae), scarab beetles (Scarabaeidae), long-horned beetles (Cerambycidae), leaf beetles (Chrysomelidae), and many other families are eaten.
Nocturnal beetle species are likely targeted most often since they are active at the same times Common Nighthawks are foraging. Tiger beetles, dung beetles, June beetles, and other nocturnal beetles are probably important prey items. The varied sizes, shapes, and habits of beetles make them a reliable and accessible insect food source.
Moths
After beetles, moths (Lepidoptera) are likely the next most significant insect prey for Common Nighthawks. Moth species eaten may include owlet moths (Noctuidae), giant silkworm moths (Saturniidae), sphinx moths (Sphingidae), and many others. Moths provide Common Nighthawks with a soft-bodied food source that can be abundant at dusk and night when the nighthawks do most of their foraging.
Since many moth species are attracted to lights, streetlights and other light sources in urban habitats may provide a convenient concentration of moths for Common Nighthawks to feed. Some moths undertake mass migrations, which may result in enormous numbers becoming available as prey for a short time when they pass through the nighthawk’s habitat.
Flies
Flies (Diptera) are another major insect prey group consumed by Common Nighthawks. Craneflies, crane flies, horse flies, deer flies, and other species are eaten. Aquatic fly species may be captured over ponds, lakes, and rivers. And flies swarming at dusk provide a convenient prey source.
The abundance and diversity of flies make them a reliable food choice for Common Nighthawks across North America. Flies characterized by erratic and fast flight patterns may pose more of a challenge for nighthawks to catch, while slower flying species likely provide easier targets.
Other Insects
In addition to the major insect groups discussed above, the Common Nighthawk takes a wide range of other insects when the opportunity arises. These include caddisflies (Trichoptera), mayflies (Ephemeroptera), termites (Isoptera), booklice (Psocoptera), true bugs (Hemiptera), and many more.
Especially large concentrations of flying ants or termites emerging from colonies may attract feeding Common Nighthawks in the appropriate habitat. And mass emergences of mayflies, caddisflies, or other aquatic insects provide abundant foraging opportunities if the nighthawks are hunting near water.
Other Prey
While insects make up the vast majority of their diet, Common Nighthawks may occasionally supplement their insect prey with other food items, especially when insect availability is low.
Spiders
Common Nighthawks sometimes eat spiders, which are arthropods like insects. Most spider prey is likely opportunistic, feeding on whatever suitable spiders are abundant and active at night. Orb-weaving spider species may be especially vulnerable to predation since they are easily detected in their webs. Ground spiders and spiders on vegetation are other possible spider prey.
Other Arthropods
In addition to spiders, other arthropod groups are sometimes found in the diets of Common Nighthawks. These include harvestmen (Opiliones), centipedes (Chilopoda), and scorpions. Again, these prey items likely represent incidental feeding opportunities rather than selected targets.
Flying Fish
There are a few reports of Common Nighthawks feeding on small flying fish species that leap out of the water. This rare behavior has been observed in locations like Florida and the Galapagos Islands where flying fish are present. The nighthawks likely only opportunistically grab flying fish that happen jump within reach.
Frogs
Common Nighthawks may occasionally eat small frogs, especially treefrogs which could be abundant in forested habitats at night. Frogs represent an incidental supplemental prey choice and are not a significant component of the Common Nighthawk’s diet.
Foraging Behavior
Common Nighthawks exhibit specialized foraging behaviors and adaptations that allow them to successfully target nocturnal insect prey.
Feeding in Flight
Common Nighthawks feed entirely on the wing. Their wide gape and small bill lined with bristles allow them to deftly scoop up insects while performing aerial maneuvers. They are also able to adjust their mouth shape to optimize capturing different types of prey.
Night Foraging
The large eyes of Common Nighthawks are adapted for crepuscular and nighttime activity. Their mottled brown, grey, and black plumage provides camouflage against the night sky while hunting. These adaptations allow Common Nighthawks to capitalize on the large numbers of nocturnal insects.
Foraging Height
Common Nighthawks generally forage relatively high, from tree-top level up to several hundred feet above ground. However, they are able to adjust their flight height based on where concentrations of insects are detected. Lower foraging may occur over wetlands, near lights sources, or in open habitats.
Foraging Habitat
Common Nighthawks exploit a variety of foraging habitats including forest openings, wetlands, riparian zones, grasslands, savannahs, and urban areas. They search for concentrations of prey items across this diverse mix of habitat types.
Migration Feeding
During migration periods, Common Nighthawks may feed opportunistically on whatever insects they encounter along their migration route. Swarms of flying ants, hatching aquatic insects, and other ephemeral concentrations create valuable feeding opportunities.
Booming and Feeding
Common Nighthawks sometimes feeding on insects attracted by their own booming displays on breeding territories. As insects congregate near the displaying male, the nighthawks may opportunistically swoop in and pick off prey put in range by the display.
Preferred Prey Features
Common Nighthawks do not feed randomly on any insects they encounter. Selective pressures have led them to preferentially target insects with particular features.
Nocturnal Insects
The Common Nighthawk’s nocturnal foraging is an adaptation to take advantage of the huge numbers of insects that are active at night. By specializing on crepuscular/nocturnal prey, Common Nighthawks avoid competition with birds that forage during the day.
Insects Attracted to Light
Common Nighthawks frequently focus their foraging in areas where artificial lights concentrate flying insects. These light sources provide dense aggregations of prey like moths and beetles that are easier to exploit than scattered insects.
Swarming Insects
Common Nighthawks have been observed targeting swarming insects including flying ants, mayflies, and termites. These ephemeral but abundant food sources are heavily utilized when available.
Soft-Bodied Insects
Moths, flies, winged ants, mayflies, and other soft-bodied insects seem to be preferred over hard-bodied beetles and grasshoppers. The softer prey may be easier to digest.
Medium to Large Insects
The gape size of Common Nighthawks limits them to consuming primarily medium-sized and larger insects. Small insects like mosquitoes are too tiny to provide worthwhile nutritional value.
Times of Day When Foraging
As a crepuscular and nocturnal species, Common Nighthawks exhibit daily peaks in foraging activity at dawn and dusk which coincide with increased insect activity.
Dusk Feeding
Common Nighthawks energetically feed for one to two hours at dusk as insect become active. This takes advantage of crepuscular insects and early emerging nocturnal species.
Dawn Feeding
They may have another shorter dawn feeding peak that targets late-flying nocturnal insects before the nighthawks roost for the day. Insects that survive the night then provide food before retiring.
Overcast Days
On overcast days Common Nighthawks sometimes exhibit increased daytime foraging since insects may remain active. But full sunlight limits daytime feeding opportunities.
Nighttime Lulls
Foraging activity tends to tail off during the middle of the night between dusk and dawn peaks. This corresponds to a lull in insect activity making foraging less productive.
Annual Changes in Diet
The diet of Common Nighthawks varies over the course of a year due to changes in insect availability and the nighthawk’s own life cycle needs.
Spring Migration
In spring the nighthawks opportunistically feed on insects encountered en route back to their breeding grounds. Aquatic insect hatches provide valuable food sources.
Breeding Season
On the breeding grounds parents increase foraging to feed themselves and their chicks. Wetlands often provide abundant prey, including beetles, moths, flies, mosquitoes, and other insects.
Fall Migration
During the southbound migration in fall, Common Nighthawks again feed opportunistically on insects wherever they are available along the migration route.
Wintering Grounds
In South America, large bodied moths make up a greater portion of the nighthawk’s diet along with beetles, flies, ants, and other insects.
Geographic Variation in Prey
While Common Nighthawks prey predominately on beetles, moths, flies, ants, and other insects across their entire range, the specific insect species present varies geographically.
Eastern US and Canada
In eastern North America diverse forest moth species are major prey items along with wetland insects like mosquitoes and midges.
Midwest
In the agricultural landscapes of the Midwest beetles associated with crops and prairies, flies, ants, and moths make up typical prey profiles.
Southwest
In drier southwestern regions ant species increases in prevalence in the nighthawk’s diet relative to other areas.
West
In the Prairie Pothole Region dragonflies become important prey when the nighthawks hunt near wetlands. And in the Pacific Northwest moth diversity declines but flies remain importance prey.
Florida
In Florida the presence of flying fish provides a unique supplemental prey source not found elsewhere within the nighthawk’s range.
Conclusion
In summary, the Common Nighthawk is an aerial insectivore that feeds predominantly on varied beetles, moths, flies, ants, and other insects active at dawn and dusk or attracted to lights at night. While showing some geographic variations, these nocturnal insects make up the vast majority of the nighthawk’s diet across their range. By foraging selectively on insects active after dark, Common Nighthawks exploit a valuable niche of abundant aerial prey.
