Bird eggs are eaten by a surprisingly wide range of animals, from raccoons and snakes to other birds and even insects. Predation is the single biggest threat to nesting birds: across studied populations worldwide, it accounts for roughly 83% of all daily nest failures, dwarfing losses from weather or abandonment combined.
Mammals That Raid Nests
Mammals are among the most common and destructive egg predators. Raccoons, striped skunks, opossums, red foxes, and badgers are considered primary nest predators in North America, and wildlife agencies in states like South Dakota actively manage their populations to protect ground-nesting birds. Raccoons, weighing 7 to 25 pounds, are particularly effective raiders because they’re strong climbers with dexterous front paws, letting them access tree nests as easily as ground nests. Opossums, roughly the size of a house cat at 4 to 14 pounds, are opportunistic feeders that readily eat eggs whenever they stumble across them during nighttime foraging.
Squirrels and chipmunks also eat bird eggs, though they’re better known as seed eaters. Gray squirrels in particular will raid songbird nests for both eggs and nestlings. Mice and rats do the same, especially in areas where their populations are dense. Weasels and other members of the mustelid family are aggressive nest raiders. Researchers studying wader nests have identified mustelid attacks by the distinctive tooth puncture marks and crushing damage left on eggshell fragments.
Hedgehogs, common across Europe, are another egg predator that often surprises people. They leave similar puncture marks on shells and can be a significant threat to ground-nesting shorebirds on islands where hedgehogs have been introduced.
Domestic and feral cats deserve a mention here too. While cats are best known for killing adult birds and fledglings, they will also take eggs from accessible ground nests.
Birds That Eat Other Birds’ Eggs
Crows, ravens, magpies, and jays are notorious egg thieves. These corvids are intelligent, observant, and will watch other birds to locate their nests. A single crow can devastate the nesting success of smaller songbirds in its territory. Gulls and other seabirds also regularly eat eggs from neighboring nests in crowded colonies, making dense nesting grounds a double-edged sword for species like terns and puffins.
Brown-headed cowbirds take egg predation a step further. As brood parasites, cowbirds don’t build their own nests. Instead, a female cowbird sneaks into another bird’s nest, removes one of the host’s eggs, and lays her own in its place. In one study of parasitized warbler nests, cowbirds damaged or destroyed eggs in 44 separate predation events during the incubation period. These events involved destroying most or all of the warbler eggs, stealing them outright, or both. Even more striking, cowbirds use a “mafia” strategy: if a host bird ejects the cowbird’s egg, the cowbird retaliates by coming back and destroying the entire clutch.
Cuckoos in Europe and other regions use a similar parasitic approach, sometimes destroying existing eggs when placing their own.
Snakes and Lizards
Snakes are highly effective egg predators because they can climb trees, squeeze into cavities, and swallow eggs whole. Rat snakes, corn snakes, and king snakes are frequent nest raiders across North America. In parts of the southeastern United States, snakes are the dominant predator of songbird nests in forested habitats.
The most specialized egg-eating snake belongs to the genus Dasypeltis, found in Africa. These snakes feed almost exclusively on bird eggs and have evolved specific adaptations for it. They can swallow eggs much larger than their head, then use bony projections from their spine to crack the shell internally, extract the contents, and regurgitate the crushed shell. No venom, no constriction, just a body built entirely around egg consumption.
Larger snakes are less picky. Burmese pythons in the Florida Everglades, an invasive species already documented eating 25 species of adult birds, have also been confirmed consuming bird eggs. Monitor lizards in tropical regions are powerful nest predators as well, using their strong claws to dig into nests and their keen sense of smell to locate them.
Insects and Other Overlooked Predators
Fire ants can overwhelm ground nests and kill developing embryos inside eggs, particularly in the southern United States where imported fire ants have spread aggressively. They’re a documented threat to quail, shorebirds, and other ground nesters. Some species of beetles and wasps also consume egg contents when they can access them through cracks or thin shells.
Fish aren’t typical egg predators, but species like largemouth bass will eat the eggs of water birds that nest on floating vegetation. Bullfrogs and large toads occasionally consume eggs from low nests near water.
How Predators Find Nests
Different predators rely on different senses. Mammals like raccoons and foxes use smell as their primary tool, which is why ground nests are especially vulnerable. Corvids rely on vision and memory, often watching parent birds fly back and forth to pinpoint a nest location. Snakes use a combination of chemical sensing (flicking their tongues to detect scent trails) and heat detection to find occupied nests.
Nest location plays a huge role in which predators pose the biggest threat. Ground-nesting birds like plovers, ducks, and quail face pressure from nearly every predator category. Cavity nesters, like woodpeckers and bluebirds, are safer from most predators but still vulnerable to snakes and small mammals that can enter the cavity. Birds that nest high in the canopy avoid most mammals but remain exposed to corvids and climbing snakes.
How to Tell What Raided a Nest
If you find a destroyed nest, the eggshell remains can tell you a lot about the predator. Researchers studying wader nests found consistent patterns: small shell chippings near a nest usually mean the eggs hatched normally, while larger fragments scattered in or near the nest point to predation. Tooth puncture marks with crushing along the shell edges suggest a mammal like a weasel or hedgehog. Clean, large openings in the side of an egg are typical of corvids, which peck through with their beaks. A nest with eggs simply gone and no shell fragments at all usually means a snake, since they swallow eggs whole and leave little trace behind.
Mammal predators often leave tracks, scat, or disturbed vegetation around the nest site. Raccoons in particular tend to leave muddy paw prints. If a nest on the ground has been dug into or the lining material is scattered, a skunk or fox is a likely culprit, since both will root around aggressively to access eggs.