Birds come in all shapes and sizes, and so do their nesting habits. While many birds build nests in trees or shrubs, some species have evolved to lay their eggs underground for protection and survival. These ground-nesting birds have developed unique adaptations that help them thrive in their environments. From penguins to owls, these underground nesters showcase nature’s incredible diversity.

Burrowing Owl

These small owls dig their own burrows or take over abandoned prairie dog holes. They line these underground chambers with grass, feathers, and even mammal dung to attract insects as food for their young. Burrowing owls can lay up to 12 eggs, though 7-9 is more common. Their underground homes protect eggs and chicks from harsh weather and many predators. Males often collect additional material to line the nest throughout the breeding season.

Kingfisher

Kingfishers excavate long tunnels in riverbanks or soft earth. These tunnels stretch 3-6 feet into the bank and end in a nesting chamber. The female lays 5-8 glossy white eggs on bare ground or sometimes fish bones. Both parents take turns incubating the eggs for about three weeks. The underground location keeps eggs safe from tree-climbing predators. Young kingfishers remain in the tunnel until they’re nearly fully grown and ready to fish.

Atlantic Puffin

These colorful seabirds dig burrows up to 3 feet deep in coastal soil or use existing rabbit holes. Puffins return to the same burrow year after year, adding grass and feathers for comfort. The female lays just one egg, which both parents incubate for about 42 days. Their underground nests provide protection from harsh ocean winds and aerial predators. Young puffins typically leave the burrow at night to avoid being spotted by predatory gulls and skuas.

Storm Petrel

Storm petrels create nesting burrows on remote islands, often among rocks or in soft soil. They visit these nests only at night to avoid predators. The female lays a single white egg that both parents incubate for about 40 days. These tiny seabirds produce a musky odor that helps them find their burrows in complete darkness after feeding at sea. Their excellent sense of smell allows them to locate their specific burrow among hundreds or thousands in a colony.

Malleefowl

These Australian birds build massive underground incubators rather than traditional nests. Males dig a pit up to 3 feet deep and fill it with vegetation. The decaying plant material generates heat like compost. Females lay up to 30 eggs throughout the breeding season. Males constantly monitor and adjust the temperature by adding or removing sand from the top. This unique incubation strategy allows eggs to develop without direct parental body heat, a rare adaptation in the bird world.

Sand Martin

Sand martins create colonies of nesting tunnels in sandy riverbanks or quarries. Their tunnels extend 2-3 feet horizontally and end in a small nesting chamber. Females lay 4-5 white eggs on a bed of grass and feathers. These sociable birds often nest in dense colonies with hundreds of burrows close together. Their underground homes deter many predators. Young sand martins often practice digging skills before establishing their own nests in subsequent breeding seasons.

Bee-eater

These colorful birds excavate long tunnels in sandy banks or flat ground. Their burrows can reach 10 feet in length but typically extend 3-5 feet. Females lay 4-7 glossy white eggs at the end of these tunnels. Multiple bee-eaters sometimes help raise the young in a cooperative breeding system. Their underground nests protect eggs from the intense heat of their native habitats. The birds remove waste regularly to keep their tunnels clean and free from parasites.

Antarctic Petrel

These hardy seabirds nest in rocky crevices and under boulders in Antarctica. They create small chambers protected from the harsh polar environment. Females lay a single egg that both parents incubate for about 47 days. The underground location shields eggs and chicks from extreme cold and fierce Antarctic winds. Their nests can be found hundreds of miles inland. The petrels navigate across featureless ice to find their specific nesting sites each season.

Bank Swallow

Bank swallows dig horizontal tunnels in vertical banks along rivers or lakes. These industrious birds create burrows about 2 feet deep using their bills and feet. The tunnel ends in a wider chamber where females lay 4-6 white eggs. They often form large colonies with thousands of pairs nesting close together. Their underground homes offer excellent protection from weather and land predators. Young swallows develop special calluses on their heels to help them move around the rough tunnel floors.

African Penguin

African penguins dig burrows in guano deposits or sand on coastal islands. These underground nests shield eggs and chicks from extreme temperatures and predators. Females typically lay two eggs that both parents take turns incubating. The burrows maintain more stable temperatures than surface nests would. Their digging ability helps these penguins adapt to environments without natural rock shelters. The parents often take turns guarding the burrow entrance while their partner forages for food.

Macaroni Penguin

Though often nesting in the open, some macaroni penguins create shallow burrows under rocks or vegetation. They scrape out depressions in soil where females lay two eggs. Usually only the second egg survives. Their semi-underground nests provide some protection from harsh subantarctic conditions. Both parents share incubation duties, often standing over rather than sitting on the eggs. The distinctive yellow crest feathers of adults sometimes protrude from burrow entrances, making them visible to researchers.

Magellanic Penguin

These South American penguins dig deep burrows in coastal slopes. Their tunnels typically extend 2-4 feet into the ground and sometimes include a bend for extra protection. Females lay two eggs that both parents incubate for about 40 days. The underground location shields eggs and chicks from intense sun, heavy rain, and predators like skuas and gulls. Young penguins often remain in or near these protective burrows until they develop waterproof plumage.

Tawny Frogmouth

While not strictly underground nesters, these Australian birds often lay eggs in depressions on the ground, partially covered by leaf litter. Their cryptic plumage makes them nearly invisible when nesting. Females lay 1-3 eggs directly on the ground in shallow depressions. The camouflaged eggs and parent blend perfectly with the forest floor debris, creating effective underground-like concealment. Their exceptional camouflage allows them to sit motionless when threatened rather than fleeing from potential predators.

Oilbird

These nocturnal birds nest in dark caves, often in areas where their nests sit in soil depressions. Females lay 2-4 eggs in these underground-like settings. Oilbirds navigate to their nests using echolocation, similar to bats. Their nestlings develop slowly, staying in the nest for up to 120 days. The cave environment provides consistent temperatures and protection from predators. Young oilbirds accumulate fat reserves that can exceed their parents’ weight before finally leaving the nest.

Rockhopper Penguin

Rockhopper penguins often create nests in underground spaces between boulders or in shallow burrows. They collect small rocks and vegetation to line these protected spaces. Females lay two eggs, though typically only one chick survives. Their underground-like nests shield eggs and chicks from the harsh subantarctic weather conditions. Both parents take turns incubating and feeding duties. The distinctive yellow crest feathers help mates recognize each other when returning to their hidden nests.

Woodpecker Finch

These Galapagos birds sometimes nest in burrows or cavities near ground level. They modify existing holes or dig shallow burrows in soft volcanic soil. Females lay 3-4 eggs in these protected spaces. Their underground nests shield eggs from the intense equatorial sun and from introduced predators. These clever birds use tools to extract insects from trees but return to underground nests. The complex tunnel systems sometimes include multiple chambers for nesting and food storage.

Chinstrap Penguin

Chinstrap penguins create nests in depressions under rocks or in small soil caves. They collect stones to form a platform inside these protected spaces. Females lay two eggs that both parents take turns incubating. Their semi-underground nests provide shelter from Antarctic winds and some protection from predatory skuas. The stones help prevent eggs from rolling and provide drainage. Parents defend these precious burrow sites fiercely from other penguins seeking shelter.

Short-tailed Shearwater

These seabirds excavate burrows in coastal slopes, sometimes extending over 3 feet into the ground. They return to the same burrow year after year, making minor repairs each season. Females lay a single egg that both parents incubate. Their underground nests remain at stable temperatures despite external weather conditions. The birds return to their burrows only at night. This species undertakes one of the longest migrations of any bird between breeding seasons.

Wedge-tailed Shearwater

Wedge-tailed shearwaters dig burrows in sandy soil on tropical and subtropical islands. Their tunnels typically extend 2-3 feet and end in a nesting chamber. Females lay one white egg that both parents incubate for about 53 days. These burrows protect eggs and chicks from heat and predators. The birds make distinctive moaning calls from inside their underground homes. Island residents sometimes call them “moaning birds” because of these eerie vocalizations that echo across colonies at night.

Fairy Prion

These small seabirds nest in burrows on remote islands. They dig tunnels about 2 feet long or use natural crevices under rocks. Females lay a single egg that both parents incubate. Their underground nests remain at stable temperatures and humidity levels. Fairy prions return to their breeding colonies and burrows only at night to avoid predators. Their excellent night vision and memory allow them to find specific burrows among thousands on dark, moonless nights.

Sooty Shearwater

Sooty shearwaters create extensive burrow systems on coastal islands. Their tunnels can reach 5 feet in length with several turns. Females lay one white egg at the end of these complex burrows. Both parents share incubation duties for about 53 days. Their underground nests protect eggs from the elements and from visual predators. These birds undertake incredible migrations between nesting seasons. Some individual burrows have been continually occupied for decades by successive generations.

Little Blue Penguin

Also known as fairy penguins, these smallest of all penguins dig burrows in sandy soil or use rock crevices. They create tunnels about 1-2 feet deep, sometimes with a slight bend. Females typically lay two eggs that both parents incubate. Their underground homes protect eggs and chicks from heat, rain, and predators. These penguins return to their burrows after dark. Their small size allows them to utilize smaller crevices and tunnels than other penguin species.

Leach’s Storm Petrel

These small seabirds excavate burrows on remote islands, often in soft peaty soil. Their tunnels extend about 1-3 feet and end in a nesting chamber lined with grass. Females lay a single white egg that both parents incubate for about 42 days. The underground location protects eggs from harsh ocean weather and aerial predators like gulls. These birds have special oil-producing glands that help waterproof their feathers and provide food for their chicks.

Rhinoceros Auklet

Rhinoceros auklets dig deep burrows in soil on coastal islands. Their tunnels typically extend 3-6 feet into hillsides. Females lay a single egg at the end of these long tunnels. Both parents share incubation duties for about 45 days. The burrows provide protection from eagles, ravens, and other predators. Adults visit nests mainly at night to avoid detection. They carry multiple fish crosswise in their bills when returning to feed their single chick.

Conclusion

These remarkable birds have evolved specialized nesting behaviors that help them survive in various environments around the world. Underground nesting provides protection from predators, climate control, and safe spaces for raising young. Next time you see a hole in a riverbank or a burrow in open ground, remember it might be home to one of these fascinating feathered architects. Their underground adaptations showcase the incredible diversity of avian nesting strategies.