Our Flying Feathered Dinosaurs

Brown Pelican, Pelecanus occidentalis

 

 

The guttural squawk of the spooked Great Blue Heron as he arose from the shore of the brackish swamp took me back 200 million years, until my ringing cell phone jarred me back to the present.  I suspect that the heron somewhat resembles its Mesozoic ancestors;  large bird with wide wingspan and slow, flapping, straight line flight.  But who knows for sure?  The fossil record is spotty and the origin of birds has been hotly debated in academia for centuries.  This is not a “settled science”.

Great Blue Heron, Ardea herodias

Remember the Genesis story.  Then God said, “Let the waters swarm with fish and other life.  Let the skies be filled with the birds of every kind, each producing offspring of the same kind”…And God saw that it was good.   It was and is very good.

GBH, click on any to zoom

In the 18th century some thought that fish and their scales were the precursor of the birds and their feathers, but by the mid 19th century scientists began to notice the many reptilian characteristics of birds.  Note the common three fingers hidden by the wing, and just substitute the heavy teeth with a lighter beak, add some feathers, and you have a bird.  But its not that easy.

Green Heron, Butorides virescens

 

A big break came in 1861, just two years after the publication of the “Origin of Species” by Darwin, when Archaeopteryx (Greek for “ancient wing”) was uncovered in a limestone quarry in Bavaria.  This 150 million year old Crow-sized fossil had the tail, spine, and claws of a reptile, but the wishbone and feathers of a bird.  Was this the transitional link?  Let the debate begin.

Archaeopteryx lithographica

The fossilization of birds is a very rare event.  Birds have thin, hollow bones and delicate feathers.  For a fossil to form the sediment must be oxygen-free and very fine in order to bring out the subtle detail of soft tissues and feathers.  That’s why Archaeopteryx was so exciting.  Later, in 1926 Heilmann published “The Origin of Birds” which suggested that birds and dinosaurs were related and shared a common bipedal reptilian ancestor 230 million years ago, but birds did not evolve from dinosaurs directly.

Great Egret, Ardea alba

Feathers evolved long before flight so clearly they must have offered some other survival advantage.  Many of the early feathered dinosaurs were much too heavy for flight and lacked other skeletal features that flight required.  The symmetrical dinosaur feather (birds have an asymmetric feather with a hollow core) were more likely used for insulation or for courtship display.  What female dino could possibly resist a male feather dance, or was it the female doing the dancing?  We’ll never know.

Great Black-backed Gull, Larus marinus, with unfortunate songbird in its talons.

Luckily there were numerous fossil discoveries in China and Spain in the late 20th century that shed new light on the origin question.  As a result, the current consensus is that birds did indeed evolve directly from Theropod dinosaurs, a group that includes the ferocious Tyrannosaurus Rex, but also a group of smaller, lighter, bipedal, raptor-like “dromeosaurs” that share many characteristics with early birds.

Buff-breasted Sandpiper, Tryngites subruficollis

The early to mid Cenozoic Era (37 to 65 million years ago) was a heyday for the birds.  The evolution of angiosperms (flowers) and grasses, and the mild climate were ideal.  Its been estimated that since their origin in the Mesozoic Era the Earth has hosted 150 thousand different species of birds.  There were two mass extinctions, however, that severely thinned the ranks.  The earlier was in the Cretaceous Period and took out many groups of toothed, aquatic birds along with all the dinosaurs.  The latter was in the Pleistocene epoch, 1.5 million years ago, a time of great climate upheaval with ice and glaciers covering vast areas of North America.  Of the 21 thousand bird species present at the outset of that epoch, only 10 thousand remain today.

By 20 million years ago most of the modern bird families and genera had appeared, but what are the most ancient birds?  Which are the true “early birds” that have survived the longest?  Only two major bird groups date back to the late Cretaceous Period in the Mesozoic Era, 65+ million years ago.  They are the Suborder Charadrii (shorebirds and gulls), and the Super Family Procellarioidea (albatrosses and petrels).  The others all came later onto the scene.

Black-footed Albatross, Phoebastria nigripes

There’s something about the dinosaurs that fascinate children, including me.  They learn the long names in kindergarten and play with their plastic models.  Maybe its their size or power, or maybe its because they ruled the Earth for so long and then disappeared so quickly and mysteriously.  Was it a comet strike or something else?  In any case, I’m so happy that some of their feathered offspring survived and continue to bring us newcomers, Homo sapiens, much pleasure today in the Cenozoic Era, Quaternary Period, and Holocene Epoch.

Avian Acrobats of Summer

 

It was just a Sunday afternoon jazz concert at the local high school and birds were the furthest thing from my mind, but when we drove into the parking lot I immediately noticed the flock of Least Terns greeting us jazz aficionados from the roof, singing their own raucous, high-pitched medley of zzreep and kvick-kvick.  Mental note:  Come back soon with binoculars and camera.

Least Tern, Sterna antillarum

The Least Tern is our smallest tern and a summertime resident along the coast.  It has a distinct white forehead patch.  They are endangered due to competition for nesting sites on the sandy beaches from sunbathers and developers.  As a remarkable behavioral adaptation the terns have moved their nesting colonies to flat gravel roofs, including our local school and Acme Supermarket.  The sunbathers have not yet followed them there.

Least Tern

I did return to observe the terns on a hot, sunny morning, timed so the sun would be behind and photography ideal.  Birds in flight, and especially these terns, present many challenges.  My best advice is to take hundreds of shots to get a few “keepers”.  You’ll need to keep exposure time faster than 1/1000 sec. and may find multiple exposure bursts helpful.  A white bird on a bright background is easily over-exposed so tend to your exposure compensation adjustments and check your results frequently.

Royal Tern, Sterna maxima

The sleek Least Terns do not do straight line flight but rather display a full acrobatic repertoire of twists, turns, barrel rolls, and hovering.  They almost seemed to relish confounding the earthbound photographer with the funny hat and large lens.

Osprey, Pandion haliaetus

According to Frank Gill in his textbook, “Ornithology”, “flight is the central avian adaptation”.  The ability to hover, dive, soar, fly upside-down and backwards, all require constant wing and tail adjustments, and set Aves apart from other classes of animals.  They’ve mastered the physics of lift, buoyancy, thrust, and drag.  Think of their refined brain and nervous system sending and receiving messages from specially designed bones, muscles, and feathers, all making this possible.  Flight, after all is the most energy efficient way of getting from point A to point B; more so than walking, running or swimming.

Tree Swallow, Tachycineta bicolor

In addition to the Least Terns there are other avian acrobats that highlight my summer birding.  The Osprey is the dominant bird-of-prey along our shoreline.  When its soaring flight changes to a hover you know it has spotted a fish and you need to be camera ready for a high speed dive. Just before impact the feet and lethal talons come out and enter the water first.  I’m still trying to capture that perfect splashing shot of impact.

Barn Swallow, Hirundo rustica

I’ve described our swallows and their acrobatic feeding frenzy over the lawn in a prior post on 8/1/2016 called “Where Have All the Swallows Gone?”.  At our location the “Barnies” seem to fly low, just over the lawn, while the feeding Tree Swallows seek insects at higher elevations.  Add an occasional Purple Martin and Chimney Swift and you have quite a show.  I find these birds the most difficult acrobats to photograph due to their rapid and erratic changes of direction.

American Goldfinch, Carduelis tristis

Let me add two more colorful performers to the list, the American Goldfinch and Ruby-throated Hummingbird.  My mother first pointed out to me the characteristic undulating flight of the goldfinch some 60 years ago.  I have yet to figure out the reason for this roller coaster ride and have concluded that perhaps the bird is doing it for pure pleasure.  In any case this allows the ID of the bird from great distances, without even seeing the striking yellow and black coloration.

Ruby-throated Hummingbird, Archilochus colubris

The “Hummers” are the world’s smallest birds and the flight of these iridescent gems is truly remarkable.  Slow motion analysis has shown a figure eight rotation of the wing allowing both the upper and lower surfaces of the wing to face downward and supply buoyancy and lift with each of the 80 beats per second.

Laughing Gull, Larus atricilla

Last week Suzanne and I sat down to a sunset dinner of crab cakes, steak, watermelon salad and chilled white wine on the screened, waterside porch.  The air was still and the evening quiet following the recent heavy rain.  I’m innocent; birds and birding were not on my mind when suddenly a mixed flock of 40 or 50 Laughing, Herring, and Ring-billed Gulls invaded our airspace and put on a captivating display.

This was not a short flyover but rather a sustained airshow of erratic, criss-crossed flight, rapid turns, and many near-misses with other gulls.  They were unusually quiet for gulls, only squawking to ward off a collision.  Seeing them periodically open their beaks and bend their necks we concluded they were feeding on an invisible-to-us swarm of insects arising from the moist lawn.  The spectacle ended as suddenly as it had begun, leaving both of us happy to have witnessed another show of the avian acrobats of summer.