Horned puffins are seabirds that belong to the auk family. They are found in the northern Pacific Ocean and are identifiable by their large triangular orange beaks. Horned puffins have a diverse diet that consists primarily of small fish, crustaceans, and other marine invertebrates. In this article, we will explore the feeding habits and diet preferences of these unique birds.
Fish
Fish make up the bulk of the horned puffin’s diet. They are pursuit divers that can dive up to 60 meters deep in search of prey. Some of the common fish species consumed by horned puffins include:
- Capelin
- Herring
- Sand lance
- Arctic cod
- Saffron cod
- Rockfish
Capelin in particular is an important food source for horned puffins. These small forage fish travel in large schools which allows the puffins to readily capture them. The abundance of capelin directly impacts their breeding success and chick survival rates. When capelin stocks are low, puffin populations tend to decline as well.
Horned puffins are generalist predators though, and can adapt to regional and seasonal differences in prey availability. During the summer breeding season, they target more energy-dense fish like herring and sand lance to meet the demands of their growing chicks. Some birds may even fly up to 48 km away from nesting colonies on daily foraging trips to find sufficient food.
Crustaceans
In addition to fish, horned puffins consume a variety of crustaceans and other marine invertebrates. Important crustacean prey include:
- Krill
- Copepods
- Amphipods
- Isopods
- Shrimp
- Crabs
Krill are tiny shrimp-like creatures that occur in dense swarms in northern waters. Horned puffins will plunge through swarms of krill with their beaks open to snatch up these nutritious crustaceans. The seasonal availability of krill impacts their distribution and breeding success.
Copepods and amphipods are other small crustaceans that provide an abundant food source for diving seabirds. Shrimps and certain crab larvae are also preyed upon when available. These crustaceans provide protein as well as important fatty acids that are crucial for the puffins’ growth and development.
Cephalopods
In addition to fish and crustaceans, horned puffins feed on various cephalopods including:
- Squid
- Octopus
- Cuttlefish
Squid and octopus inhabit the deeper ocean waters where puffins dive and forage. Squid are swift swimmers but puffins are able to grasp them with their sharp beaks. Octopus are ambush predators that are also snatched up when possible. Cuttlefish are less common prey but provide an occasional food source.
Cephalopods have high energy density and are rich sources of lipids, proteins, and amino acids important for the growth and development of nestlings. However, they only make up a small portion of the overall diet.
Other Prey
In addition to the main prey groups above, horned puffins opportunistically feed on various other marine animals including:
- Polychaete worms
- Snails
- Clams
- Sea urchins
- Jellyfish
- Sea anemones
Polychaete worms, snails, clams, and other mollusks are preyed upon during dives. Urchins, jellyfish, and anemones are also eaten when encountered. These diverse groups supplement the puffin’s diet and provide a wide range of nutrients.
Diet Differences Between Breeding and Non-Breeding Birds
The diet of horned puffins differs somewhat between breeding and non-breeding birds as well as seasonal availability of prey species. Here is a comparison:
Breeding Birds | Non-Breeding Birds |
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When breeding, the puffins are constrained to foraging closer to their nesting colonies. They select more energy-dense fish to rapidly provision chicks. Herring and sand lance are perfect prey for this purpose.
Non-breeding birds have greater flexibility to forage further out to sea and across a wider range of habitats. They can target a more diverse array of prey and rely more heavily on invertebrates like krill and squid during some seasons.
Foraging Strategies
Horned puffins have evolved several key adaptations and behaviors to exploit their prey:
- Pursuit diving – They plunge into the water and pursue swift-moving fish like herring.
- Fish-herding – Groups of puffins can herd fish into dense bait balls before diving in to feed.
- Deep diving – They dive to depths up to 60 meters in search of prey.
- Wing-propelled swimming – Their short wings allow excellent maneuverability underwater.
These hunting strategies allow horned puffins to capture a wide variety of fish, crustaceans, and other prey. Their ability to access deep waters and herd prey gives them an advantage over many seabird species.
Dietary Shifts Based on Prey Availability
The relative availability of key prey groups can shift significantly between seasons and years. Horned puffins exhibit dietary flexibility to adapt to these fluctuations:
- During years when juvenile herring are abundant near breeding colonies, they can compose 60-99% of chick diets.
- When herring declines, sand lance and other small fish increase in diet.
- Crustaceans like krill become more important when fish availability is low.
- Cephalopods are eaten more frequently by non-breeding adults.
This ability to shift prey targets allows puffin populations to withstand natural ups and downs in the availability of key food species. However, extreme scarcity of critical prey like herring and sand lance can negatively impact breeding success.
Geographic Differences in Diet
There are some regional and geographic differences in the diet of horned puffins based on local oceanographic conditions and prey communities:
- In the Bering Sea, puffins rely more on polychaete worms, krill, and cephalopods during summer.
- In the Sea of Okhotsk, Pacific sand lance and capelin are primary prey.
- Around the Pribilof Islands, juvenile pollock are important when abundant.
- In the Gulf of Alaska, herring, sand lance, and capelin predominate.
Despite these differences, small schooling fish like herring, sand lance, and capelin form the nutritional backbone of puffin diets throughout their range when available.
Impact on Health and Breeding
The availability of high-quality prey has important impacts on the health and breeding success of horned puffins:
- Years with abundant, energy-dense prey result in better adult body condition going into breeding season.
- Well-fed adults lay earlier and produce larger eggs and clutches.
- Chicks grow faster and fledge at heavier weights when food is plentiful.
- Fledging success is higher in productive prey years.
In poor prey years, adults are often emaciated and stressed, resulting in delayed breeding, smaller eggs and chicks, and higher chick mortality. Prolonged scarcity of key prey can cause puffin productivity and populations to decline until food availability rebounds.
Anthropogenic Impacts on Prey
Declines in prey like herring and sand lance due to human activities may be contributing to reduced puffin breeding success in parts of their range. Potential factors include:
- Overfishing of key prey species.
- Competition with commercial fisheries for prey.
- Habitat degradation from trawling, pollution, coastal development.
- Climate change impacts on timing of prey availability.
Careful management of fish stocks and protection of critical marine habitats will be key to ensuring puffins have access to sufficient food resources into the future.
Conclusion
In summary, horned puffins are adaptable marine predators that target a variety of small fish, crustaceans, and other prey. Capelin, herring, and sand lance are critical when available, but puffins can shift among other prey when needed. Abundant access to energy-rich foods is key to adult body condition, timing of breeding, chick growth rates, and overall productivity. Conservation of puffin populations in a changing ocean environment will require careful stewardship of marine ecosystems to maintain healthy prey populations.