Saturday, June 27, 2020

HERPETOFAUNA IN FARMLAND STREAMS

     One recent June afternoon, while scanning the opposite shore of a clear-flowing stream with binoculars, I saw a few handsome painted turtles sunning themselves on that stream bank.  And as I admired the red and yellow stripes on those turtles' necks and front legs, I heard a chorus of green frogs belching from the same waterway.  Again using binoculars, I saw a few of those google-eyed frogs half-hidden in the blobs of algae in still water along the stream's shoreline.   
     Certain kinds of amphibians and reptiles are declining in numbers in southeastern Pennsylvania, but other species seem to be holding their own here, including in slow stretches of flowing streams and creeks in this area's farmland, a human-made habitat that is not ideal for herpetofauna to live in.
     People generally think of these creatures living in ponds and marshes of standing water, and they do.  But green frogs, bull frogs, Fowler's toads, painted turtles, snapping turtles and northern water snakes have adapted to residing in the more placid currents of smaller, fast-running waterways, which increases the living space, food resources and numbers of these aquatic creatures.  These amphibians and reptiles are the most omnipresent and readily seen and heard in local waterways.
     All these creatures are cold-blooded, so they are dormant and hidden away in winter.  But they are active and noticeable in the warmer days of each year.  
     All these herps are greenish or brownish; well camouflaged, which blends them into their habitats for their own protection against predators, including herons, mink, raccoons and other species.  And these amphibians and reptiles are secretive, and quiet for the most part.  They hide in shoreline vegetation where predators usually can't see them. 
     However, painted turtles and northern water snakes regularly bask in sunlight on rocks, shorelines and limbs fallen in waterways.  They do that to warm up to have the energy to hunt food and mates.  But basking can make those creatures more visible. 
     Female snakes that give live birth also bask in sunshine to provide warmth for the growth of embryos inside them.  Female water snakes generally give birth by the beginning of September.
      All these critters, except painted turtles, are totally carnivorous.  Frogs and toads ingest invertebrates, snapping turtles consume fish, ducklings and other creatures, and water snakes eat frogs, tadpoles and small fish.  Painted turtles ingest water snails and other small creatures, but also lots of aquatic plants.
     These species of herpetofauna have different ways of reproducing.  Male frogs and toads either croak, moan or trill in slow, shallow water, according to their kind.  Each female frog or toad spawns hundreds of eggs in gelatin-like blobs or strings, again according to its type, in sluggish water.  Turtles, however, lay eggs in holes they dig in the soil near the water they live in.  June is when most turtles lay eggs.    
     These kinds of herpetofauna do live in quiet water in southeastern Pennsylvania cropland.  But they also dwell in slow parts of streams and creeks here, which has helped maintain the populations of these amphibians and reptiles.  Adapting is a key to success.

Monday, June 22, 2020

SWIFTS AND SWALLOWS

     Chimney swifts and four kinds of swallows are interesting to watch on the wing to catch flying insects with their beaks during the warmer months here in Lancaster County, Pennsylvania, as elsewhere.  All migrants that wintered farther south, these small, streamlined birds sweep and swerve swiftly and gracefully through the air much of each day, every day, to catch their prey, and creating a show that people can enjoy.
     Although swifts are related to hummingbirds, they are built more like swallows because of convergent evolution.  Swifts and swallows have nearly identical lifestyles in a shared habitat, which shapes them into similar-looking creatures to make the best use of that habitat.  Both groups of small birds are streamlined and have long, powerful wings and flight muscles for swift, sustained flight.  And both groups have large mouths for their body size so they can snare their prey on the wing.    
     Swifts generally are higher in the sky than the swallows when gleaning insects from the air, which reduces competition among these birds for food.  And, although these birds weave speedily among their fellows while snaring flying insects, I've never seen them collide with each other.  They obviously have quick reflexes.
     These insect-eating birds are also interesting in their adapting to feeding and nesting in human-made habitats, including farmland, cities and suburbs.  Swifts and swallows are probably more abundant today because of that adapting than they ever were in their life histories.
     Chimney swifts traditionally raise young in protective hollow, broken-off trees in the eastern United States.  But these adaptable birds are now nesting down the inside of certain chimneys, which, to them, are like hollow, broken-off trees.
     Each pair of smoky-hued swifts in flight snaps off tiny, dead twigs from trees and glues those twigs to the inside wall of a chimney to make a cradle for their young, using their own saliva as a glue!  Parent swifts feed insects to their offspring on those twiggy platforms.  And the first flights of young swifts need to be good to exit the chimneys they were born in.
     Great swarms of post-breeding chimney swifts swirl, round and round, over large chimneys in cities and suburbs around sunset each evening in August.  Round and round, each horde of swifts spins over its chimney of choice, with numbers of swifts dropping into the gaping, sky-pointing hole with each pass.  At first, a few swifts enter the chimney, then more and more with each spiral until the remaining revolving mass of birds sweeps down the chimney like smoke in reverse.  Now all the swifts are down their protective, vertical shelter for the night, each bird clinging upright with its tiny, sharp toe nails imbedded into the rough surface of the chimney's inner wall.
     In September, flocks of swifts migrate south to northern South America where they spend the northern winter catching flying insects.  But next April, they will be back in the United States again, ready to raise young.
     Barn swallows are so-named because they raise young in mud-pellet nurseries plastered to support beams in barns and under small bridges in farmland.  They traditionally nested on cliffs and the mouths of caves in North America.  But they obviously have adapted to building their mud cradles in human-made structures.        
     Barn swallows pick up mud in their beaks and fly each mud pellet, one at a time, to their nest site on the side of a support beam, where they plaster that pellet to the beam.  They make a cup-like structure with an open top to receive their eggs.  Adults feed their progeny flying insects.
     Barn swallows are iridescent purple on top and orange below, with males having deeper colors than their mates.  These swallows scatter over farmland to catch flying insects and line up on roadside wires between feeding forays to rest and digest.  By August, they begin gathering for their migration south to Central and northern South America to pass the northern winter catching flying insects.  But they will be back in North America the next April. 
     Tree swallows and purple martins traditionally hatch chicks in tree cavities in North American cropland, the former species in single hollows, while the colonial-nesting martins need multiple holes near each other.  Single bird houses are erected for tree swallows to nest in, while apartment bird boxes are erected for martins.  Those built cavities have greatly increased the numbers of the adaptable tree swallows and martins over the years.
     Tree swallows and martins are attractive as they zip over meadows, fields and lakes after flying insects.  Male tree swallows are iridescent blue on top and white below, while their mates are more grayish above.  Male martins are iridescent deep-purple all over while female martins are gray on top and dingy-white underneath.
     Tree swallows and martins also line up on roadside wires between feeding forays and during their migrations south for the winter.  Sometimes large numbers of each kind are seen on wires, causing great spectacles, as they rest and digest the insects they caught.
     Rough-winged swallow pairs are look-alikes, with both genders being gray-brown.  Traditionally, individual pairs of these swallows either dig nesting holes in stream banks, or use abandoned belted kingfisher burrows in those same stream banks to raise youngsters.
     Today, some pairs of rough-wings nest in drainage pipes under bridges over smaller waterways and in retaining walls at waterways.  Those human-made nesting sites are fine until heavy rain flushes out young, grassy nursery and all.  Some pairs start over, if it is not too late in the season.
     Swifts and swallows are interesting to observe catching insects in the air.  And they have intriguing life histories.  And they are built similarly because they share a niche of careening through the air after flying insects.            

Wednesday, June 17, 2020

SMALL, SUBURBAN-NESTING BIRDS

     Several kinds of small birds nest in suburban areas in southeastern Pennsylvania, and across much of the northeastern United States.  Some species traditionally nest in deciduous woods, some in conifers, and others in shrubbery.  All these habitats exist, in miniature, in suburbs, including ours, thus drawing in the birds.
     Each bird species is as attractive and interesting on lawns dotted with trees and bushes as they are in their original habitats.  Because each kind of bird has its own niche and foods, there is little competition for food and nesting sites among these species.  And through their adapting to suburbs for raising young, these birds have higher populations and we humans have the joy of experiencing their beauties at home.
     Song sparrows are adaptable thicket birds that rear offspring in suburban shrubbery.  This species ingests invertebrates during warmer months, but eats seeds in winter and regularly comes to bird feeders.  Like all sparrows, these are brown and darkly-streaked, which camouflages them among bushes.  Male song sparrows sing lovely, lively songs from warm afternoons in mid-February into the middle of summer.
     Downy woodpeckers, chickadees, tufted titmice, white-breasted nuthatches and house wrens, being woodland birds, nest in used woodpecker holes and other tree cavities, and boxes erected for them to hatch youngsters.  All these kinds of small birds are permanent residents, except the house wrens, which are migratory.  These species don't all nest in every suburban area.  Each suburb has its own community of nesting birds.
     All these birds are camouflaged among trees and consume invertebrates during warmer months.  Male titmice whistle "Peter, Peter, Peter ........" while male house wrens sing lively, bubbly songs.  All these types of birds, except the wrens, visit feeders in winter.  
     Many pairs of migratory chipping sparrows and permanent resident house finches build nurseries in planted arborvitae, or northern white cedar trees, on lawns.  The look-alike genders of chippies have rufous crowns, while male finches have pink on their heads, chests, wings and tails.  Female house finches, however, are gray with darker streaking, which camouflages them.
     Male chippers regularly sing a dry trill that identifies them.  Male house finches, however, sing bubbly, cheerful songs as early as warm afternoons in February.
     American goldfinches and ruby-throated hummingbirds hatch babies in petite, beautiful cradles in sapling trees on some lawns.  Male goldfinches are bright-yellow with black wings and tails, and a jaunty black "cap" on their foreheads.  They sing lively tunes, often while in roller-coaster flight.
     The olive-yellow female goldfinches build their lovely nurseries of fine grass, thistle down and spider webs, and attach those nests to crotches of twigs with more spider webbing.  Goldfinches feed their young a regurgitated porridge of pre-digested seeds, particularly thistle seeds.           
     Female hummers make lovely, tiny nurseries of plant down and spider webs, and attach those cradles to the tops of twigs with more spider webbing.  Then they camouflage their charming creations with bits of lichens.  Those petite cradles aren't generally noticed by humans from below.  Mother hummingbirds feed flower nectar and tiny insects to their nestlings.
     And there are a few other kinds of small birds that build nurseries on buildings and other human constructions.  These birds are Carolina wrens, house sparrows and chimney swifts.
     Permanent resident Carolina wrens build cradles in all kinds of odd places, including inside garages and sheds, under porches and decks, inside outdoor grills and so on.  They also build nurseries in firewood piles and rock fences.  What they are seeking, of course, is shelter for their babies, which they feed a variety of invertebrates.
     Resident house sparrows raise young in crevices in buildings and other, human-made objects.  One house sparrow nesting site that's been used by them for many years is a metal box with a hole in it on an utility pole.
     But the neatest nurseries in suburbs are those of chimney swifts down the inside of certain chimneys.  This type of swift winters in northern South America, but migrates to the United States to raise young.  Each swift flies about most of each day, all summer, in pursuit of flying insects to ingest and feed their young.
     Chimney swifts in flight snap off tiny twigs from trees.  They fly down inside their protecting nesting chimneys with those twigs and glue each one to the inside wall to create a platform, using their own saliva as a glue.  They lay their four eggs per female on those twig cradles.
     These small, adaptable birds make suburban lawns more appealing and interesting.  And these species have higher populations because of increased nesting sites in the human-made habitats they adapted to.         
    

Thursday, June 11, 2020

TROPICS COME NORTH

     One sunny summer afternoon, I was sitting on top of a wooded stream bank and looking down through leafy boughs to the clear-running creek below when I suddenly saw a beautiful male Baltimore oriole fly low over the water.  Looking at him from above, his brilliant, black and orange plumage pattern was exceptionally striking to me.  His bright feathering among the green foliage of summer made me think of tropical America where he, and other kinds of beautiful, summering birds about his size in southeastern Pennsylvania, and elsewhere, go to escape northern winters.  These attractive, brightly-colored birds help bring the colorful tropics north for the summer.  And I have seen them all over the years. 
     Two species each of orioles, grosbeaks and tanagers have adapted to raising young each summer in southeastern Pennsylvania's agricultural areas, and elsewhere.  By adjusting to raising young in less than ideal conditions for each kind of tropical bird, these migrant species have prospered and maintained their numbers, for the most part, in spite of human activities and encroachment.  It pays to be adaptable.   
     Males of each kind of these tropical birds are beautifully feathered, and sing, to attract females of their respective species for rearing offspring, and repelling could-be, rival males.  But females of each kind have lovely feathering that blends them into their surroundings for their safety. 
     Each species has its own niche, which reduces competition for food and nest sites in which to raise their broods.  These lovely, tropical birds, come north to rear youngsters in the northern summer, feed a variety of protein-packed invertebrates to their babies.
     Baltimore orioles commonly nest in tall trees, particularly sycamores, along streams and creeks in cow pastures.  They also rear offspring on other kinds of lone trees along country roads and farm lanes in cropland.  The pale, yellow-orange female orioles build their deeply-pouched cradles of twigs, rootlets and vines on the tips of twigs that hang over water or roadways.  Such nurseries keep young orioles relatively safe from predators.    
     Adult male orchard orioles have unique and pretty plumage patterns, being deep-rusty below and black on top.  Their mates, however, are yellowish-green, which camouflages them.  This species, like Baltimore orioles, nests in lone trees in meadows.  But orchard orioles also raise young in older orchards with bigger trees.  Females of the present species build open cup nurseries of twigs and grasses on forks of twigs.
     Orchard orioles seem reclusive and usually are difficult to spot among the trees and other plants of pastures and orchards.  But males sing sweet, warbling songs that often give away their presence.
     The attractive adult male rose-breasted grosbeaks are mostly black on top, white below and have a patch of red on their upper chests.  Their mates, however, are brown and streaked, which camouflages them around their nurseries in woodland edge shrubbery.
     Some pairs of these grosbeaks from the American tropics have adapted to nesting on the edges of woodlots that overlook farmland.  They have additional nesting sites and we humans who know where they nest have added beauties to enjoy in farmland.
     Blue grosbeaks were limited to nesting in the southern half of the United States, but are now slowly pushing farther north to hatch chicks.  The attractive adult males of this lovely species are blue with beige wing bars, but their mates are brown.  Males sing from taller vegetation in the hedgerows, and roadside wires where they are quite visible.
     Blue grosbeaks rear young in thickets of shrubbery and vines in hedgerows between fields and along country roads in cropland.  Those thickets protect the young from snooping people and most predators.       
     Scarlet tanagers are tree top birds in oak forests.  But this bird species has adapted to oak woodlots and smaller woods in farm country, much to the birds' benefit. 
     Adult male scarlet tanagers are crimson with black wings and tails, but their mates are olive in color, which is good blending among tree top foliage where they place their cradles.
     Although these tanagers can be overlooked in tree tops, there are two ways to find them.  Listen for the males' raspy songs that sound like singing from American robins that have sore throats.  And scarlet tanagers sometimes come down to farm fields to catch invertebrates, making these beautiful birds more visible to us.     
     Looking quite tropical, adult male summer tanagers are red all over, but their females are yellowish-brown.  This species has been limited to nesting in the southern United States, but is now slowly pushing north to rear offspring.  This species, like its cousin, prefers oak woods to hatch babies.
     Interestingly, summer tanagers specialize in catching bees and wasps on the wing.  They batter these insects on twigs to get rid of the stingers before consuming them.    
     All these beautiful birds escape northern winters by migrating in late summer to Central and northern South America.  But while they were nesting here in southeastern Pennsylvania, and elsewhere, they were representatives of the tropics they winter in and, probably, originated in.  They are a bit of the tropics come north.  

Tuesday, June 2, 2020

SPRING ON THE MISSISSIPPI FLYWAY

     I've seen several kinds of water-loving birds along the Mississippi River and one of its backwaters in Wisconsin during the spring of 2020.  I saw most of those birds on extensive mud flats and shallow, sky-reflecting channels amid marsh-and-tree-covered islands, all of which are bordered on both sides by tree-covered hills.  All this I saw through a live camera mounted along the river and our home computer screen. 
     Spring is born from the chilly womb of winter.  Several each of bald eagles, ring-billed gulls, Canada geese and mallard, common goldeneye, bufflehead and common merganser ducks winter along the Mississippi, as long as some water remains ice-free.  The eagles and gulls catch and scavenge fish.  The magnificent eagles roost overnight on trees on the islands, while flocks of gulls spend winter nights on the flats. 
     The geese and ducks spend winter nights bobbing on the water, or sitting on ice.  The majestic geese, and mallards, "tip-up" to feed on vegetation in the shallows and nearby marshes.  And the related, similar-looking goldeneyes and buffleheads dive under water from the surface to eat small mollusks and crustaceans, while mergansers catch small fish.  Obviously, these water birds can live together in harmony because they have different foods.
     By early March, certain kinds of migrating birds stop for a few weeks on this part of the Mississippi to rest and gain nourishment.  Hundreds of similar-looking lesser scaups and greater scaups, which are related bay ducks, dive underwater from the surface to ingest aquatic vegetation, mollusks and crustaceans.  But soon they migrate farther north and west to their breeding territories around the "potholes" in the mid-western prairies of Canada and the United States to raise young.
     Scores of stately, north-bound tundra swans rest among the mud flats and shallow channels where they dine on underwater plants by reaching their long necks down to them.  Everywhere the swans go and everything they do is highlighted by their reedy, whistling calls that identify them.  And by late March they are on their way north to the Arctic tundra where they will raise cygnets. 
     Flocks of tall, stately sandhill cranes roost at night on some of the mud flats and shallows in the Mississippi in April. There they rest between feeding forays on the flats and in nearby marshes.  And all the while their gutterel, rolling trills precede the seeing of them.  And, like the swans, the cranes soon push farther north to the tundra of Canada, Alaska and eastern Siberia to raise one or two young per pair.     
     Scores of handsome American white pelicans, and double-crested cormorants, both fish-eaters, are on the Mississippi in Wisconsin in April.  These species co-exist because they have different ways to catch fish.  Cormorants dive under water from the surface and search deeper waters for their finny prey.  White pelicans, however, work together by dipping their large beaks, like nets, at the same time in shallow water to scoop up fish.  These pelicans raise young by fish-filled, Canadian lakes. 
     By April, too, gadwalls, green-winged teals, blue-winged teals and northern shovelers, all species of small ducks, are in the shallows among the marshes and mud flats of this part of the Mississippi.  There these kinds of pretty ducks tip-up to consume aquatic plants from the bottoms of the marshes and shallows.  All these species, too, hatch ducklings in the pot-holes of American and Canadian mid-west prairies.  
     Many striking red-winged blackbirds are in the island marshes along the Mississippi to raise young among the tall grasses.  Male red-wings are black all over, with red shoulder patches they raise when singing from swaying grasses to attract mates and reject rival male red-wings.  Each female red-wing attaches her grassy nursery to grass stems a few feet above the water or soil of a marsh.
     A few each of great blue herons and great egrets stop along the shallows of the Mississippi in Wisconsin to catch fish.  They are entertaining to watch stalking their prey in the shallows. 
     Early in April, loose flocks of stream-lined, north-bound Bonaparte's gulls and tree swallows sweep swiftly over the Mississippi, often at the same time, but not together.  Both these lovely species of migrating birds are entertaining to watch swooping gracefully over the river after flying insects, and small fish and other tidbits off the water in the case of the gulls.  Those gulls are small and dainty for their role in life.
     Tree swallows nest in tree cavities and bird boxes.  Bonaparte's hatch young in twig cradles they make on spruce trees near lakes in Canada's boreal forests, something other kinds of gulls don't do.
     In May, flocks of migrating shorebirds of several kinds trot over the mud flats and in shallows after small invertebrates to eat.  Most of them are so small and well camouflaged that they are often tough to spot on the mud. 
     Some of the more commonly seen migrant shorebirds on Mississippi flats and shallows include least, semi-palmated and pectoral sandpipers, dunlin, greater and lesser yellowlegs, ruddy turnstones, semi-palmated plovers and avocets.  But by the end of May, most of these beautiful shorebirds are on their way to the Arctic tundra to hatch offspring.       
     The flats and shallows of parts of the Mississippi River in Wisconsin are entertaining with migrating birds from early March to the end of May.  And the most convenient way to experience these birds is through the live camera and a computer screen right at home.