Least terns are small seabirds that are found along the coasts of North America. They are known for their aerial diving displays as they hunt for small fish in shallow waters. While agile fliers and divers, least terns face threats from various predators.
Mammals
Some of the mammals that prey on least terns or their eggs include:
- Foxes – Red foxes and gray foxes will dig up and consume tern eggs. They may also grab adult terns and fledglings.
- Raccoons – These opportunistic omnivores readily eat tern eggs and chicks when they can access nesting colonies.
- Coyotes – Coyotes are efficient predators that can threaten least terns, especially in areas where coyote populations are high.
- Feral cats – Roaming domestic cats will prey on tern chicks and eggs.
- Rats – Rats may consume unattended tern eggs or injure chicks.
Mammals are most likely to threaten terns when they inhabit or have access to barrier islands and beaches where terns nest. Constant predation pressures from mammals have caused tern populations to decline where habitat overlaps.
Birds
Aerial and wading birds that prey on terns include:
- Gulls – Herring gulls, great black-backed gulls, and other species eat tern eggs and chicks.
- Crows – American crows rob tern nests.
- Hawks – Peregrine falcons, sharp-shinned hawks, Cooper’s hawks, and merlins grab adult terns in flight.
- Owls – Short-eared owls and snowy owls may hunt terns.
- Skimmers – Black skimmers compete with terns and may prey upon tern eggs.
- Herons – Great blue herons, green herons, and black-crowned night herons stalk and consume tern chicks.
Birds that share coastal nesting grounds with terns pose frequent threats. Terns may attack and attempt to drive off predator birds through loud calls and aerial diving.
Reptiles
Reptilian predators of least terns include:
- Snakes – Some snakes, like black racers, milk snakes, and yellow-bellied racers, may eat unattended tern eggs.
- Alligators – In the southeastern U.S., juvenile alligators can threaten tern colonies along inland rivers.
Snakes raid tern nests for eggs, while alligators grab adults and chicks that nest over water. Tern colonies near waterways inhabited by alligators are at the highest risk.
Fish
Large predatory fish are potential threats to least tern chicks that enter the water. Some fish that could prey on chicks include:
- Bass – Largemouth bass and other bass species will consume small chicks.
- Pike – Northern pike ambush small prey in shallow waters.
- Catfish – Bullheads and channel catfish may eat chicks.
- Perch – Yellow perch, striped bass, and white perch prey on small fish and possibly chicks.
Predation by fish may be highest at tern colonies along inland lakes and rivers. Chicks face the greatest risk of fish predation in their first few days after hatching.
Other Threats
Beyond direct predators, least terns also face other threats to their survival from humans:
- Habitat loss from development
- Disturbance of nesting colonies
- Pollution and contamination
- Climate change impacts on coastal habitat
Terns require undisturbed beach habitat for nesting and have been displaced by human activities in many areas. Their limited and fragile habitat makes terns vulnerable to extinction without conservation measures.
Predation Solutions and Conservation
Some measures used to protect terns from predators and conserve the species include:
- Habitat protection of nesting grounds
- Predator exclosures and barriers around colonies
- Controlled habitat manipulation like vegetation removal
- Predator trapping and removal
- Constant monitoring against disturbances
- Public education to minimize human disturbance
- Captive rearing and release programs in some areas
Ongoing conservation efforts aim to learn more about tern predators, minimize predation risks, preserve habitat, and increase tern population sizes. With proactive management, least tern populations can recover from years of decline.
Key Facts
In summary, key facts about least tern predators include:
- Mammals like foxes, raccoons, coyotes threaten eggs and chicks.
- Birds like gulls, herons, hawks prey on adults and chicks.
- Reptiles including snakes and alligators take eggs and chicks.
- Fish may prey on young chicks entering the water.
- Humans disturb colonies and degrade habitat.
- Conservation requires habitat protection and managing predators.
Conclusion
Least terns face predation pressures from all angles while nesting and foraging. Mammals, birds, reptiles, and fish all consume eggs, chicks, and adults. Beyond direct predation, human activity also threatens terns through disturbances and habitat loss. Ongoing conservation and management efforts aim to learn more about tern predators, minimize risks, and protect fragile breeding grounds and populations. With proactive strategies, the least tern may recover from decades of decline and thrive well into the future.
