Becoming Penguins?

     Alcids are a family of seabirds that live and breed in the northern latitudes of the northern hemisphere.  They range in body length of 17 inches to eight inches, depending on the species, and look and act much like penguins, most of which live in the southern hemisphere.  Alcids are largely black on top and white below, as penguins are dark above and white underneath.  Alcids are plump and stand nearly upright when at rest on seaside cliffs.  Their legs are near the rear of their bodies, as are penguins', to give them steering while they swim under water.  Alcids and penguins both "fly" under water with their wings, but alcids can also fly through the air with rapid whirs of wing beats.  Another trait that penguins and alcids share is their spending winter in the open ocean to catch prey animals, the former species in the southern hemisphere and the other in the northern.
     Because they live in similar niches, though in opposing hemispheres, the unrelated alcids and penguins look and behave much alike.  Their environments shaped them, literally, to be what they are.  Alcids and penguins are specialized in the same ways to make their livings, though alcids can still fly through the air, which allows them access high on islands and cliffs to raise babies in relative safely.  Penguins nest on low shores and ice, and developed layers of fat as insulation against the intense cold of Antarctica, therefore they lost the power of flight. 
     There are six kinds of alcids, razorbills, thick-billed murres, thin-billed murres, Atlantic puffins, dovekies and black guillemots, nesting along the Atlantic sea coast of North America, most species in large, crowded colonies on rocky islands and cliff edges along the ocean where native predators are limited.  Today, however, cats, rats, dogs and other introduced animals create havoc among certain colonies of alcids, reducing their populations. 
     Each female alcid of every type, but black guillemots, lays one egg each breeding season: Each guillemot female lays two per season.   The eggs of razorbills, thin-billed murres and thick-billed murres are strongly tapered to keep those eggs from rolling off narrow cliff ledges.  Imagine the number of eggs of these species that fell off cliffs until a genetic quirk caused tapering of egg shapes so they would roll in tight circles and not off rock walls.  Because more chicks from tapered eggs survived to adulthood, all these birds now lay tapered eggs.  that genetic quirk helped the reproductive success of those bird species. 
      Puffins hatch young in underground burrows for the safety of the offspring.  They dig many of those nursery tunnels themselves.
     All species of alcids feed on small fish, crustaceans and molluscs.  They get their food by diving into the ocean from the air and swimming with their wings to snare their prey.  When their beaks are full of victims, they lift from the water and whir back to their breeding colonies to feed their young.           Each alcid species nests in habitats that separates it from its relatives, thus reducing competition for nesting space and food to an extent, though there is overlapping.  Razorbills breed in cavities in boulders in the coastal waters of Greenland, Iceland and in North America south to Maine.  They winter on the Atlantic Ocean south to Long Island. 
     Thick-billed murres breed on cliffs from the Arctic Ocean south to Hudson Bay and the Gulf of St.Lawrence, where they are preyed on by peregrine falcons and gyrfalcons.  This species winters on the ocean.
     Thin-billed murres nest on rocky islands and cliffs in high latitudes around the northern hemisphere.  Winters on the ocean south to the latitude of Maine.
     Atlantic puffins nest exclusively from Greenland south to Maine in North America.  It winters from Massachusets as far north as there is open water on the ocean.
     Dovekies are the smallest alcid species.  This bird breeds north of the Arctic Circle.  It winters in great flocks on the ocean below the pack ice of the polar regions, usually south to the Virginia coastline, or beyond during some winters.  Sometimes they can be spotted on the Atlantic from land on the Lower 48.  
     Black guillemots don't nest in large colonies.  They breed in cracks in cliffs from the Arctic Ocean south to James Bay and Maine.  They winter along leads in the pack ice of the Arctic Ocean and Atlantic and Pacific Oceans.   
     Alcids are a family of birds in northern latitudes that are becoming penguin-like.  It is amazing the number of traits those two unrelated families of birds share, simply by living in similar environments.  Genetic codes and habitats work together to shape the life in each environment to be ever more efficient in getting a living in each habitat.