EXTREME ADAPTING

     It is amazing how adaptable some forms of life are.  Two kinds of birds, gray gulls and sand grouse, demonstrate that quite well.

     We think of gulls nesting along the shores of seacoasts, lakes and rivers, but gray gulls raise young in the Atacama Desert of northern Chile, a unique habitat for nesting gulls.  The Atacama is noted as the driest place on Earth.  

     Gray gulls live and feed along the Pacific Coast of South America, but adapted to nesting in the Atacama where there are few predators to prey on their eggs and chicks.  The South American gray fox is their chief predator.

     Gray gulls nest from November through January.  Each female gray gull lays two or three cryptic-colored eggs in a shallow scrape in the sand of that desert.  And when her chicks hatch, she and her mate take turns shading and guarding the chicks while the other parent flies twenty to sixty miles to the Pacific Coast to consume mole crabs and other invertebrates in the beaches and small fish from the water.  Then that parent flies back to the Atacama with food and water in its crop to feed its chicks by regurgitation into the babies beaks.  In that way, gray gulls can raise young in a desert.    

     There are several gray gull nesting colonies in the Atacama that are populated by thousands of nesting gray gulls, an obviously successful species.  Adult grays are pretty in their own plain way.  Both genders are light-gray all over with white heads, black legs and beaks and a white edge to the rear of each wing.  Young gray gulls are brown all over, which camouflages them.

     Sixteen kinds of sand grouse live on the ground of scattered deserts in Africa and Asia.  Those sixteen species developed because the deserts are scattered.  But still, being related, all types of sand grouse have characteristics in common.  Flocks of each kind ingest seeds and insects from the ground.  And daily those birds fly swiftly across tens of miles of desert for water at water holes.

     Though not related to doves, sand grouse are dove-sized and shaped, with long, powerful wings and short legs.  They even fly in groups like doves, when they are not raising young as individual pairs.  And they feed on seeds on he ground like doves.  Sand grouse and doves illustrate convergent evolution.  Their similar habitats shaped them to resemble each other.  

     Each female sand grouse lays two to three eggs in a scrape in the sand or soil.  The young hatch fluffy and able to feed themselves right away.  Like their parents, the young are well camouflaged on the ground.  But there are few predators on sand grouse in the deserts, except hawks waiting in ambush at the water holes.  A lack of predators is why gray gulls and sand grouse nest in deserts.  

     The chest feathers of male sand grouse are designed to soak up and retain two tablespoons of water.  After getting his fill of water, each male soaks up water into his chest feathers and carries that water, in flight, for several miles to his chicks in the desert.  The youngsters use their beaks to squeeze out the water from their father's feathers.  In that way, sand grouse can raise chicks in predator-free deserts.  

     Gray gulls and sand grouse nest in extreme niches to raise young relatively safely from predators.  And both types of birds have done so successfully.