I was fascinated by the following passage from Terry Tempest Williams’ book REFUGE.   Evolution is truly wondrous;  birds born in trees are helpless for much longer than birds who are born in ground nests.  What a perfect plan, since birds born in ground nests would be easy prey if they were helpless like the tree birds.

This reminds me of another type of perfection in nature.  Mammals who nurse their young frequently, like humans, have thin milk.  Other mammals, like whales, who nurse very infrequently, have milk as thick as cream.  Each is perfect for the animal’s circumstances and the baby’s needs.–April Moore 

  

      “Most of the gulls I watched at the Bird Refuge were incubating eggs, an activity which takes from 23 to 28 days.  Both sexes share in the responsibility.

     “I wondered in the midst of so many gulls and so many eggs, how the birds could differentiate between them.  They do.  Parental recognition.  The subtle distinctions in patterning and coloration among individual egg clutches test my eye for discrimination.  Each brood bears its own coat of arms.

     “Young gulls are precocial, which means they are relatively well developed at hatching.  They are covered with a thick coat of natal down, can leave the nest soon after they hatch, and can feed themselves within a short time.  Precocial young are typical to most waterfowl, an adaptation against predators of ground-dwelling birds.

     “In contrast, altricial young are those birds born helpless, usually naked and with closed eyes, completely dependent on their parents for a sustained period after hatching.  Altricial young are more common to passerine birds, which have the advantage of tree nesting.  They can afford to be helpless.”  

This entry was posted on Tuesday, August 12th, 2008 at 7:35 pm and is filed under Insights and Visions on the State of the Earth. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.