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Auk

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Auks are specialized seabirds belonging to the family Alcidae. This family is part of the order Charadriiformes. It includes diverse birds like puffins, auklets, murres, and murrelets. There are 25 extant or recently extinct species within the family. These birds are found throughout the Northern Hemisphere. While they look similar to penguins, they are not closely related. Instead, they are an example of convergent evolution. This means they developed similar traits because they live in similar environments.

Auks
Auks

The physical design of an auk is a complex biological compromise. Most auks have sacrificed some mobility on land to become better swimmers. Their wings are short and built for diving. However, they must also be functional enough for flight. Because their wings are short, auks must flap them very rapidly to stay airborne. This creates a trade-off between two different types of movement. For example, Uria guillemots are highly efficient underwater divers. In contrast, puffins and auklets are better adapted for flying and walking.

Puffin Mrkoww
Puffin Mrkoww

Auks are pursuit divers that use wing-propelled locomotion. This means they use their wings to push themselves through the water to catch prey. This method is very similar to how penguins hunt. In their habitats, auks often compete with cormorants for food. However, cormorants use their strong feet to power their dives. To avoid direct competition, auks often feed further offshore. Different species target different food sources based on their strength. Strong-swimming murres hunt fast, schooling fish. Meanwhile, smaller auklets focus on slower-moving krill.

Alca torda Roest 2003
Alca torda Roest 2003

Scientific understanding of auk evolution has changed significantly over time. Researchers once believed auks were one of the earliest distinct lineages. Recent genetic analyses have proven this was incorrect. Auks actually changed radically from wading shorebirds into diving seabirds. This transformation was driven by strong natural selection. Genetic data suggests their closest living relatives are skuas. These two lineages separated approximately 30 million years ago (Mya). Auks are now placed in the Lari suborder alongside gulls.

Blackguillemot44
Blackguillemot44

The fossil record provides important clues about the history of these birds. The earliest unequivocal fossils date back to the late Eocene, about 35 Mya. The genus Miocepphus is the earliest known from good specimens. Scientists believe auks likely first evolved in the Pacific Ocean. This is because the Pacific has a greater diversity of fossils. Early movements to the Atlantic likely occurred by traveling south. This was necessary because no northern opening to the Atlantic existed at the time.

Xantus adult
Xantus adult

Auks are pelagic birds, meaning they spend most of their lives on the open sea. They only come ashore to breed. Most species are monogamous and form lifelong pairs. They typically lay a single egg each year. Different species use different nesting strategies to survive. Some, like Uria guillemots, nest in large colonies on cliff edges. Others, like Cepphus guillemots, breed in small groups on rocky coasts. Puffins, auklets, and some murrelets nest in burrows.

Marbled murrelet breeding plumage
Marbled murrelet breeding plumage

Environmental factors strictly limit where auks can live today. They are restricted to cooler northern waters. Their hunting method becomes less efficient as water temperatures rise. As temperature increases from 0°C to 10°C, the speed of small fish can double. Since the birds do not increase their speed at the same rate, they cannot catch them easily. This is why auks in California and Mexico rely on cold upwellings. They stay near the continental shelf to find the food they need to survive.

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🖼️ Images & Media (6)
File:Auks.jpg
Auks.jpg
File:Alca torda Roest 2003.jpg
Alca torda Roest 2003.jpg
File:Puffin Mrkoww.jpg
Puffin Mrkoww.jpg
File:Xantus adult.gif
Xantus adult.gif
File:Blackguillemot44.jpg
Blackguillemot44.jpg
File:Marbled murrelet breeding plumage.jpg
Marbled murrelet breeding plumage.jpg
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