DIVERGENT WOODPECKERS

      Being related from a common ancestor, woodpeckers, worldwide, have unique characteristics in common, including two toes in front of each foot and two in back and stiff tail feathers that prop each bird upright on vertical tree trunks.  They all have sturdy, chisel-like beaks that chip into dead wood of trees to extract and ingest invertebrates.  And they all excavate hollows in trees or large cacti with their bills, in which they raise young.  See the attractive feather patterns of these woodpeckers, and their ranges, in a field guide or on a computer.   

     But five species of woodpeckers in North America, including northern flickers, yellow-bellied sapsuckers, acorn woodpeckers, white-headed woodpeckers and Lewis' woodpeckers have mostly diverged their menus from invertebrates in dead wood of trees to other kinds of foods.  By consuming other foods, these woodpeckers reduce competition for sustenance with their relatives, allowing more kinds of woodpeckers to thrive.     

     Flickers, for example, run their lengthy tongues into ant colonies in the ground.  The ants, and their larvae and eggs, stick to flickers' sticky tongues, which those birds repeatedly pull back into their beaks to swallow that insect food.  No other woodpecker species does that.  And flickers are brown and black-streaked, which camouflages them on the ground.  

     Yellow-bellied sapsuckers have the unique habit of poking rows of holes into the soft bark of trees.  Later they come back to those little punctures to sip the sugary nectar oozing from those small holes.  That sap is also attractive to a variety of insects, small birds and squirrels that also ingest it.

     Acorn woodpeckers live in family groups in oak woods from Central America, north to Mexico, California and Oregon.  These are the only species of woodpeckers that chip thousands of shallow holes in dead wood in trees in which they store acorns for winter use, jamming in one nut per cavity.  Trees used to store many acorns are called granary trees.       

     White-headed woodpeckers live in mountain, old-growth pine forests of the American and Canadian west.  This species feeds on large pine seeds they wedge into crevices to hold them fast.  And they flake away bark to probe under it to pull out invertebrates to eat.

     Lewis' woodpeckers live in the woods of the western United States.  This species seldom chips into dead wood after invertebrates, as many types of woodpeckers do.  Lewis' perch on treetops and watch for passing flying insects.  When potential victims are spotted, Lewis' sweep out flycatcher-style and grab them in their beaks, then fly back to a perch to ingest them.  They also consume some nuts.

\     These kinds of woodpeckers departed, at least in part, from traditional woodpecker ways of getting food, which reduces competition for it.  And gleaning different food sources helps create the different species.  All life on Earth is adaptable, which allows many species to survive indefinitely, and diverge into many relate species with a common ancestor.   

Comments

Post a Comment

Popular posts from this blog

TWO GULLS AND A TERN

     Via a live camera and our computer screen, I saw flocks of post-breeding ring-billed gulls, Franklin's gulls and Caspian terns resting together, in early autumn of 2021, on mud flats and in inch-deep water on Lake Onalaska, a large, shallow back-water off the Mississippi River in northern Wisconsin.  These attractive birds are noted for regularly flocking together because they share inland, large-water habitats for nesting and wintering, and scavenge and catch fish and other aquatic creatures.  But each species also has lifestyles of its own, which sets it apart.             All these handsome, easily-seen species are graceful, buoyant fliers, quite adaptable and common across much of North America.  They are interesting to watch going about their daily activities, including nesting, getting food and loafing in big gatherings on rivers and larger lakes.      Ring-billed gulls, so-named for a black ring ...
Read more

MATS OF WATER PLANTS

     By August, varying-sized, green mats of algae, duckweed and water stargrass float together on the surfaces of certain ponds and still backwaters of creeks in Lancaster County, Pennsylvania.  Algae grows in long, matted strands, and duckweeds are tiny, flat plants that grow in colonies on water surfaces.  Stargrass colonies root in muddy bottoms.  Each plant's long leaves undulate in currents and the single yellow flower barely emerges from the water's surface to be pollinated.       Together, those mats of algae, duckweed, and stargrass in bloom, look like tiny islands in the water, and remind me of lawns with dandelion flowers flourishing in them.  And, those mats of small, aquatic plants create niches that several kinds of small creatures use for a variety of reasons.      Certain kinds of attractive and entertaining damselflies and dragonflies rest on those mats, after aerial feeding forays on small, flying in...
Read more

WINTERING BIRDS ALONG STREAMS

      Four kinds of mostly-brown, small birds, including permanent resident song sparrows and killdeer plovers, and wintering Wilson's snipe and American pipits, winter regularly, but sparingly, along streams and brooks in southeastern Pennsylvania farmland meadows.  But, being beautifully camouflaged on mud flats, gravel bars and shallows on the shores of those small waterways, these adaptable, interesting birds are nearly impossible to see, until they move or fly, and then they are quick to duck out of sight on brown flats and gravel bars, and among tufts of vegetation along shorelines.       In winter, all these birds ingest invertebrates from waterway shorelines where the running water doesn't freeze and thaws the flats and bars it laps over.  Each bird species snares invertebrates in its own way.  (Song sparrows also consume weed and grass seeds.)  The sparrows, killdeer and pipits pick up invertebrates from the surfaces of the...
Read more