Puffins are seabirds that nest in colonies on cliffs and rocky islands around the northern Atlantic and Pacific Oceans. There are four main species of puffin: the Atlantic Puffin, the Tufted Puffin, the Horned Puffin, and the Rhinoceros Auklet. Puffins nest in burrows or crevices on cliffsides and lay a single egg each breeding season. The eggs and chicks of puffins are vulnerable to predation by a variety of animals. In this article, we will discuss the main predators of puffin eggs across their range.
Some quick facts about puffin eggs:
– Puffin eggs are large relative to the size of the adult birds. An Atlantic Puffin egg is around 10% of the adult’s body weight.
– The eggshells are thick and rough in texture. This helps protect the egg from cracking.
– Incubation takes around 40 days before the chick hatches. Both parents share incubation duties.
– Puffins only lay one egg per season. If that egg is lost, the parents do not lay a replacement egg that breeding season.
Predators on Land
On land, the main predators of puffin eggs are various birds and mammals. The types of egg predators depends on the location of the colony. Some common predators include:
Gulls
Gulls are found throughout the range of puffins and are major egg thieves. Species like Herring Gulls, Great Black-backed Gulls, and Glaucous Gulls will readily eat puffin eggs if they can access the nesting burrows. Gulls tend to target unattended nests or nests early in the incubation period. Some gulls are even capable of excavating closed off burrows to reach puffin eggs.
Corvids
Corvids like ravens, crows, and magpies are intelligent birds that are puffin egg opportunists. They raid puffin colonies looking for undefended eggs to eat. Ravens in particular use their strong bills to crack into puffin burrows and eat the eggs inside.
Foxes
Foxes are found on many puffin nesting islands. Red foxes and Arctic foxes dig up puffin burrows and consume eggs. They also prey on adult puffins and chicks. Fox predation can be a major problem at some colonies, significantly reducing reproductive success.
Mink
The introduced American mink causes problems for many seabird colonies. Mink are agile predators that hunt adult puffins, chicks, and raid burrows for eggs. They were introduced to places like the United Kingdom and have caused severe declines in some puffin breeding sites.
Bears
In Alaska, brown bears and black bears forage on puffin eggs when the colonies are accessible. Bears will dig into burrows andalso hunt adult puffins that are nesting in more exposed crevices.
Predators at Sea
Puffins face threats not just on land, but at sea as well. Puffins are pursuit diving seabirds, catching small fish to bring back to feed their chick. While away from the colony foraging, some predators will target adult puffins and reduce the chance of the chick being fed.
Eagles
Bald eagles and white-tailed eagles are aerial predators that will pick off puffins from the water’s surface. Eagles need open water near the puffin colonies to successfully hunt them. So the proximity of open water impacts how much of a threat eagles pose.
Gulls
The same gull species that steal puffin eggs on land will also hunt adult puffins at sea. Herring gulls, great black-backed gulls, and glaucous gulls are all opportunistic predators of seabirds.
Peregrine Falcons
Peregrine falcons are speedy predators that target puffins in flight. They capture adult puffins in mid-air as they come and go from the breeding colony. Peregrines can significantly reduce puffin numbers at some sites.
Foxes
On some islands, foxes don’t just steal eggs from burrows, they also patrol shorelines and hunt adult puffins in shallow water. This adds extra predation pressure beyond just egg theft.
Defense Mechanisms
Puffins have evolved some defensive strategies to protect their egg from predation:
– Nesting in hidden burrows or hard-to-access crevices. This makes the eggs harder for predators to find and reach.
– Making the egg shell very thick and tough. This makes the egg harder to crack open.
– Nesting in dense colonies. There is safety in numbers from some predators.
– Aggressively defending the nest burrow from intruders. Puffins will fight off predators with their strong beaks.
– Only leaving the egg unattended for short periods to go fishing. This gives predators little time to sneak in and steal the egg.
– Relying on their excellent diving ability to escape predation at sea. They can rapidly dive deep and escape from surface predators.
Effects of Predation on Puffin Populations
Heavy predation on puffin eggs and adults can negatively impact puffin breeding populations. Some observed effects include:
– Lower number of breeding pairs at colonies. Higher attrition of adults means fewer remaining puffins nesting.
– Reduced reproductive success. With fewer eggs surviving, fewer chicks fledge each season.
– Changes in behavior. Excessive predation can make puffins abandon traditional nest sites if they become too dangerous.
– Shifts in distribution. Puffins may move away from predator-heavy islands and seek safer nesting locations elsewhere.
– Declining population trends long-term if puffin numbers cannot compensate for predation impacts through sufficient reproduction success elsewhere.
To conserve puffin populations, managing problematic egg predators may be necessary through methods like predator exclusion fences, live trapping removals, and habitat management to reduce predator access.
Conclusion
Puffin eggs face predation threats from a diverse suite of birds and mammals. Gulls, corvids, foxes, bears, eagles, falcons, and mink are among the major puffin egg predators that reduce reproductive success at colonies. Puffins have adaptations to help protect their single precious egg each season, but predation remains a pressure that can significantly impact populations. Understanding these predator-prey dynamics is important for proper management and conservation of puffins into the future. Reducing puffin egg loss to predators where needed may help stabilize populations undergoing declines. With thoughtful stewardship, hopefully puffins can continue thriving and nesting successfully despite the risk of predation.
References
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[7] Rodway, Michael S. “Activity patterns, predatory behaviour and reproductive chronology of breeding Peregrine Falcons in Rankin Inlet, Northwest Territories.” Arctic (1991): 33-39.
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[10] Miles, Will TS, et al. “Predators reduce breeding success by forcing incubating parents off nests.” Proceedings of the Royal Society B: Biological Sciences 284.1860 (2017): 20171885.
Predator | Location | Threat Level |
---|---|---|
Herring Gull | Atlantic Canada | High |
Red Fox | Iceland | Moderate |
Great Black-backed Gull | Scotland | High |
American Mink | United Kingdom | High |
Bald Eagle | Alaska | Moderate |