Many species of birds are active at night, especially when it comes to finding food. Nocturnal feeding patterns allow birds to take advantage of food sources that are not available or abundant during the day, avoid competition from diurnal species, and minimize the risk of predation. Some birds are exclusively nocturnal feeders while others utilize a combination of nocturnal and diurnal strategies. The types of birds that feed at night include owls, nighthawks, nightjars, kiwi, some species of shorebirds, and even some songbirds.
Why Do Some Birds Feed at Night?
There are several key reasons why certain birds have adapted to feed at night:
- Avoiding competition – By being active at night, nocturnal species can access food sources without competing with diurnal species for resources. This reduces competition for prey and allows multiple species to coexist.
- Avoiding predators – Many predatory birds that hunt during the day cannot see well at night. Feeding under cover of darkness provides safety.
- Accessing prey – Nocturnal insects, rodents, and other creatures are more active and available to predators at night.
- Specialized adaptations – Some birds have specialized eyesight, hearing, or feeding behaviors adapted to function at night.
- Metabolic differences – Some bird species have slower metabolisms that allow them to utilize food over longer periods between meals.
The combination of reduced competition, increased prey availability, and lower predation risk makes nocturnal feeding an effective strategy for many bird species.
Types of Birds That Feed at Night
Owls
Owls are highly adapted for hunting at night. With their large, forward-facing eyes and exceptional night vision, owls can easily locate prey after dark. Different owl species employ various nocturnal hunting techniques, such as perching and waiting to ambush prey, gliding slowly through open areas listening for prey, or even chasing prey on the wing. Many owl species swallow their prey whole and regurgitate indigestible parts like bones, fur, and feathers in the form of pellets. Common nocturnal owl species include:
- Great horned owl
- Barred owl
- Barn owl
- Eastern screech owl
- Great gray owl
- Northern saw-whet owl
- Short-eared owl
Nightjars
Nightjars are a family of nocturnal insect-eating birds with long wings, short legs, and very short bills. They have cryptic brown, black, and gray plumage that provides camouflage when roosting during the day. At night, nightjars take flight and hunt for insects in open areas or woodlands using their large mouths to scoop up prey in flight. Their huge gape allows them to consume large quantities of insects each night. Common North American nightjars include:
- Common nighthawk
- Common poorwill
- Chuck-will’s-widow
- Whip-poor-will
Night-herons
This group of stocky herons feeds nocturnally on fish, crustaceans, insects, small mammals, and other prey along shorelines and wetlands. Their stout bills are effective for capturing prey at night. Some night-heron species include:
- Black-crowned night-heron
- Yellow-crowned night-heron
Kiwi
Kiwi are unique nocturnal birds endemic to New Zealand. With a highly developed sense of smell and specialized bill for probing soil and leaf litter, kiwi forage at night for invertebrates, grubs, worms, and other prey. Their whisker-like feathers even help them locate prey in the dark.
Seabirds
Many seabirds exhibit nocturnal or crepuscular (active at dusk and dawn) feeding behaviors that coincide with the vertical migrations of marine fish, plankton, and other prey. Species such as shearwaters, storm petrels, penguins, and some albatross feed at night over open oceans.
Shorebirds
Beaches and intertidal mudflats bustle with insect and crustacean life at night when shorebirds do much of their foraging. Many shorebirds use their senses of touch and taste to find prey at night since they can’t rely as much on vision. Some shorebirds like sanderlings may forage both day and night opportunistically.
Songbirds
While most songbirds sleep at night, some species – particularly swifts, nighthawks, and nightingales – forage nocturnally on flying insects. These agile species are well-adapted to hunting on the wing in darkness.
Nocturnal Adaptations For Feeding
To find food in darkness, night-feeding birds exhibit specialized traits and behaviors compared to diurnal species:
Enhanced Senses
- Vision – Nocturnal hunters often have larger eyes placed more forward on their heads. Their retinas are dominated by rod cells optimized for low-light vision.
- Hearing – Owls and other nocturnal species possess asymmetrical ear placement and feather adaptations to channel sound waves and precisely locate prey in the dark.
- Smell – Species like kiwi have highly developed olfactory bulbs and abilities to detect scents while foraging at night.
- Touch – Many shorebirds use touch to feel for prey concealed in wet sand or mud, probing with their bills.
Specialized Hunting Techniques
- Perch-hunting – Owls often watch patiently from an elevated perch then swoop down to ambush detected prey.
- Ground-gliding – Nightjars slowly cruise low over fields to catch insects in their oversized mouths.
- Aerial pursuit – Swifts and nighthawks chase and capture flying insects on the wing at night.
- Stalking prey – Herons stealthily stalk wetland edges at night to spear fish.
Cryptic Plumage
Mottled black, brown, and grey coloration helps night birds remain hidden from prey while roosting or hunting in darkness.
Light-reflecting Eyes
Eyes that shine in light, like those of owls, help birds locate one another at night. This also intimidates predators.
Reduced Activity During Day
To conserve energy, nocturnal species rest and enter torpor during daylight hours.
Challenges of Nocturnal Feeding
Despite their adaptations, night-feeding birds face substantial obstacles, including:
Diminished Vision
Even nocturnal birds see far worse at night than diurnal birds see during the day. Limited vision impacts prey detection and predator avoidance.
Risk of Predation
While fewer predators hunt at night, those that do, like foxes, raccoons, and cats, pose a significant threat. Night feeding necessitates constant vigilance.
Difficulty Locating Prey
It is far harder for birds to spot stationary or hidden prey in darkness compared to daylight. Nocturnal feeders must concentrate and utilize other senses to find food.
Higher Energy Requirements
Low light conditions likely increase energy expenditures during foraging. Nocturnal birds need efficient metabolisms and energy-dense foods.
Disrupted Circadian Rhythms
Being active at night and resting by day may interfere with internal circadian biological clocks, which can affect health and behaviors.
Nocturnal Feeding Patterns and Strategies
Different groups of nocturnal birds exhibit various feeding patterns and strategies:
Owls
- Hunt from perches then swoop down to grab prey on the ground or water surface
- Fly low and slow over areas listening for prey rustling in vegetation
- Pursue prey in flight during aerial assaults
- Primarily consume small mammals like mice, voles, rabbits; also take birds, amphibians, reptiles, insects
- Regurgitate indigestible fur, feathers, bones as pellets
- Larger owls may take medium-sized mammals or waterbirds
Nightjars
- Forage by aerial hawking – catching insects in mouth and throat while flying
- Use widely gaping mouths to scoop up moths, beetles, flies, mosquitoes
- May perch briefly to capture prey spotted from vantage point
- Consume insects almost exclusively
Shorebirds
- Probe into mud or wet sand along beaches, estuaries, shorelines
- Hunt by touch using bill to detect buried prey
- Prey includes marine worms, mollusks, crustaceans, insects
- May peck at surface prey or fish in shallow water
- Some chase receding waves to catch exposed prey
Seabirds
- Forage over open ocean waters at night when fish and plankton rise nearer the surface
- Plunge dive from flight into water to pursue prey underwater
- Pursue schools of fish forced to surface by predatory marine mammals
- Scavenge scraps from fishing vessels or predator kills
- Prey includes fish, squid, krill, planktonic crustaceans
Songbirds
- Capture flying insects illuminated by artificial lights or the moon
- Aerial pursuit of moths, beetles, flies, mosquitoes
- Occasional gleaning of non-flying insects from leaves or branches
- Consume mostly insects; some species take berries or nectar
Examples of Nocturnal Bird Diets
Great Horned Owl
Prey Items | Percent of Diet |
---|---|
Mammals (rabbits, mice, voles, squirrels) | 50% |
Birds (grouse, ducks, passerines) | 35% |
Reptiles & Amphibians | 10% |
Invertebrates | 5% |
Eastern Whip-poor-will
Prey Items | Percent of Diet |
---|---|
Moths & beetles | 85% |
Flies & mosquitoes | 10% |
Ants & bees | 5% |
Black-crowned Night-heron
Prey Items | Percent of Diet |
---|---|
Fish | 65% |
Crustaceans | 15% |
Aquatic insects | 10% |
Worms & leeches | 5% |
Amphibians & reptiles | 5% |
Conclusion
Many bird species across diverse groups exhibit nocturnal activity patterns when it comes to finding food. By hunting at night, these birds can take advantage of darkness to access prey unavailable during daylight hours while avoiding competition with other bird species. Owls have excellent low-light vision to hunt small mammals. Nightjars use their enormous gapes to trap insects. Shorebirds probe wet sand for marine prey. Seabirds prey on fish forced near the ocean’s surface after dark. And some songbirds opportunistically snack on insects attracted to night lights. While night feeding presents challenges like poorer vision and higher predation risk, birds demonstrate fascinating behavioral and anatomical adaptations to the darkness – from enhanced sensory abilities to cryptic plumage. Understanding the strategies and dietary habits of nocturnal avian hunters provides insight into their unique niches within ecosystems.