Civilization?

Canada Geese, Branta canadensis

I’m again reminded at how fast “nature” attempts to undo our efforts at civilizing the world. When we recently returned home to Chesapeake country after six months in Florida the meadow around the house was three feet tall, the deer, red fox, and ground hog were crisscrossing the land as if it was theirs, turtles were digging nests in the the weed covered gravel driveway, and the starlings were nesting in my boat lift cover again. At least the eagle decoys had spooked the geese into the neighbor’s greener pastures

Eastern Bluebird, Scalia sialis

We returned late this season; the forsythia blooms were long gone and the daffodils had just passed their peak, but the peonies were still bursting upward, inches every day. The watermen on the bay had put away their oyster tongs and were now running the trotlines and netting the delectable Blue Crabs. The corn was two inches tall and it will soon be summer with crabs, sweet corn, and strawberry shortcake on the menu. But first I would have to regain control of this yard.

Barn Swallow, Hirundo rustica

It occurs to me that we humans are also a part of the natural world, seeking to survive and create a safe abode. My house is in many ways similar to the Osprey nest built on the channel marker or the Barn Swallows who build their muddy home under the dock. The difference is the width of the swath our species cuts, at least in its modern version.

Osprey, Pandion haliaetus

Another difference is our unique awareness of the effects of our swath on the world and our attempts to mitigate them. The bay is clearer and the underwater grasses more abundant than in prior decades and the air is cleaner. We can celebrate these improvements knowing that there is still work to be done.

European Starlings, Sturnus vulgaris

On my recent road trip through middle America I traced in reverse the route of the European colonists who finally broke through the Appalachian Mountains at Cumberland Gap and elsewhere into the unspoiled lands of Kentucky, Tennessee, and later into Indiana, Illinois, and Missouri. They understandably cleared land for planting, hunted the abundant game, and built their hovels, filling a new niche, much different than that of their nomadic forerunners.

Missouri River at Eagle Bluffs

I crossed the mighty Mississippi and Missouri Rivers which still scoff at our human efforts to control them by periodically flooding their banks. We build dikes and dams, but cannot completely stem the flow. I birded one of these areas, Eagle Bluffs, on the banks of the Missouri, near Columbia. This is a 4400-acre wetlands and marsh providing habitat for year-long and migrating birds. A network of gravel roads on the dikes separates the numerous ponds and gives excellent views of the wildlife.

Bald Eagle, Haliaeetus leucocephalus

During the visit in late April waterfowl were the leading species; I don’t ever recall seeing more Blue-winged Teal. Living up to the locale’s name I saw a nesting Bald Eagle and several fishing kingfishers, but no migrating warblers.

Blue-winged Teal, Anas discors

Other birders have also wondered at the apparent scarcity of migrators this spring, but Cornell’s BirdCast has a reassuring report. Their research, including radar data, showed a whopping 400 million birds aloft on the night of May 14. “These massive flights may not, however, have produced spectacular birding on the ground…as meteorological phenomena that normally concentrate migrants are absent”. In other words, the weather has been favorable for the birds to keep pressing north rather than land and treat us birders to the typical spring show.

Belted Kingfisher, Ceryle alcyon

Standing on the banks of the Missouri I was impressed by the force of the downriver flow, draining much of our continent. One can picture the steamships of an earlier era; in fact, the “Plowboy” sunk there and is said to be buried in the sand and silt at Eagle Bluffs. I didn’t have time to dig around for it. My next stop heading east was the Audubon Museum in Henderson, Kentucky on the Ohio River perhaps a post for another day.

Common Yellowthroat, Geothlypis trichas

The recent road trip and my return to the home patch in Maryland emphasize again to me that we are not just onlookers or observers of nature, but rather full-fledged participants. In fact, a substantial partner given our relatively late arrival on the scene and our ability to alter the world for better or worse. But just when we think we are becoming the masters, the earth quakes, the tides roll in, the river valley floods, the virus spreads, the wells run dry, and we are again put in our place.

The Cumberland Gap and Its Birds

Daniel Boone escorting settlers through the Cumberland Gap, 1851-52, by George Caleb Bingham

Humans have migrated through the gap in the Cumberland Mountains, both to the east and to the west, for eons, and before that the trail was pounded hard and widened by the bison searching for pasture and salt licks. It is named for the Duke of Cumberland, son of King George II of England and has always attracted my attention as a possible destination. This was heightened by the messianic picture above showing Daniel Boone leading his entourage into the promise land to the west. In a recent road trip from Kansas City to Baltimore I purposely chose a route through the historic gap; it also gave me a chance to do a little birding in the historic park.

Tufted Titmouse, Baeolophus bicolor

The geology of the gap’s formation is fascinating but beyond the scope of this so-called birding blog, but let me make this one point. I spent two nights at the gap in the town of Middlesboro, Kentucky, not realizing at the time that I was smack in the middle of a 300 million year-old meteorite impact crater that contributed to the formation of this mountain pass.

Eastern Phoebe, Sayornis phoebe

It is difficult for us moderns to understand the formidable barrier that the Appalachian Mountains presented for the early colonists along the east coast. For a hundred years only a few intrepid explorers, traders, and missionaries ventured over the range. Eventually several gaps and trails, previously blazed by the large game and Native Americans were rediscovered by the colonists.

Black Vulture, Coragyps atratus

The Cumberland Gap was the premier passage, right at the boundaries of Tennessee, Virginia, and Kentucky. By the mid 18th century settlers had broken through and poured into the fertile region and cheap or free land in Kentucky and in the Ohio River Valley. By 1810 two to three hundred thousand new settlers had made this journey over the Wilderness Road, through the gap, and to the west. Quoting Moses Austin from 1796, “Ask these Pilgrims what the expect when they git to Kentucke. The answer is land. Have you any? No, but I expect I can git it. Have you anything to pay for land? No. Did you ever see the country? No, but everybody says it is good land”.

Cumberland Gap and surroundings

Today, when one drives through the gap you actually go through a tunnel which, in typical 20th century fashion was blasted through the Cumberland Mountains. But near the gap there is a wonderful historic park with myriad trails offering many birding opportunities. My road trip traced in reverse the westward migration of humans, but cut across at right angles the springtime avian migration to the north. It was mid April and my hopes were high for encountering some of those flocks.

Red-bellied Woodpecker, Melanerpes carolinus

Pinnacle Overlook is at the mountain top, guarding the northern edge of the gap and commands a marvelous view to the south. In the early morning I decided to test the endurance of my old but faithful car by tackling the switch-backs up the mountain. At the top I was rewarded with the view as the solitary morning visitor. The bird life there, however, was sparse with only the incessant call of the titmouse and a couple of nesting phoebes disturbing the peace.

Yours truly at Pinnacle Overlook, Homo sapiens

I was soon joined by a second birder, a gentleman and octogenarian who actually claimed to be related to Daniel Boone. We enjoyed the view together while sharing birding adventures. While we were jabbering a Sharp-shinned Hawk flew by the peak at our eye level, perhaps migrating to the north on the rising thermals. Vultures circled below. My friend became excited when I told him about a trip I was planning to Wyoming and Montana, and inexplicably, he started removing his outerwear and displayed the back of his tee shirt which was a map of Glacier National Park. He implored me to enter the park at his right shoulder, the easterly gate, and proceed to his left shoulder for the best route. Just another example of a helpful birder, as one frequently meets on the trail.

Downy Woodpecker, Picoides pubescens

At the top of the mountain there is a ridge trail that is noted as a warbler trap during spring migration. I just found woodpeckers and jays. I believe I was early for the warblers this far north. While I was far from home searching for birds at the gap, my friend and fellow birder, Andy, was sending me pictures of all the warblers he was seeing back in south Florida, just a few miles from my home. Timing is everything in this sport.

Carolina Wren, Thryothorus ludovicianus

But along the ridge trail I saw something that Andy did not see. That was a Civil War cannon embankment called Fort McCook by the Unions and Fort Rains by the Confederates. It changed hands several times during the war. The gap was of strategic value during that conflict, to the extent that the armies hauled their heavy guns all the way up the mountain. Supplying the fort was difficult for both sides, and as the war progressed the real value of the mountain top fort came into question. Now the site is peaceful and just a series of grassy mounds and historic markers explaining the 160 year-old wartime scene.

Song Sparrow, Melospiza melodia

The park has a great visitor’s center at the base of the mountain and several flatter birding trails. Here, it was the welcomed spring melody of the Song Sparrow that greeted me. Overall my bird sightings were meagre but my knowledge of our human migration was enhanced. The short stay at the Cumberland Gap Historic Park was a rewarding experience. The warbler sightings will have to wait for another day.

Bird Sleep

 

Just after sunset, with fading light and falling temperature, wave after wave of Canada Geese circled our cove and gracefully landed.  They joined a raucous flock of geese, perhaps 500 or more, apparently judging the cove to be a safe haven for the night.  But with all the honking I wondered if any, myself included, would ever be able to fall asleep.  With darkness, however, they did quiet down, except for the occasional honk from a vigilant sentry goose proclaiming all is well.

Canada Geese, Branta canadensis

As one ages sleep patterns become an issue, and sometimes even a topic of conversation and concern.  Being a curious birder I decided to do a little research, emphasis on little, as to the sleeping habits of our feathered friends.  What’s their sleep pattern, how much do they need, where do they go at night, can they sleep while flying, etc.?  I also scanned my photo archives looking for pictures of sleeping birds.  Unfortunately I usually delete pictures of birds with their eyes closed, but did find a few suitable for this post.

Eastern Screech Owl, Megascops asio

On my bedside nightstand there is a fascinating book by Matthew Walker entitled “Why We Sleep”.  It’s mostly about humans but does include a great chapter about the evolution of sleep.  According to the author a biologic sleep requirement must have evolved very early, as all animals, even insects, demonstrate sleep cycles.  You can confirm this with the characteristic brain waves on the EEG’s of sleeping animals and by periodic cycles of non-arousal of small insects.

Yellow-crowned Night-Heron, Nyctanassa violacea

Although all animals require some sleep, the amount and style vary considerably.  Walker states that the length of the restorative sleep requirement is determined by the complexity of the animal’s nervous system.  Both the length and type have evolved separately for every species and are balanced by the equally important need for wakeful hunting, eating, nest-building, and blog writing.

Dunlins, Calidris alpina

We are all familiar with the two types of sleep, REM and non-REM, identified by their characteristic brain waves.  It’s interesting that REM, the shallower sleep stage associated with dreaming, only occurs in mammals and birds.  It is, therefore, a later creation in the evolutionary sequence.  I consider it an “eye opener” to think of birds actually dreaming.

Common Nighthawk, Chordeiles minor

Although there are similarities between avian and human sleep, there are also many differences.  Birds demonstrate hemispheric sleep, the amazing ability to let half the brain sleep while the other half stays wide awake, perhaps as a defense for lurking predators.  At some point this split reverses and the other half falls asleep.  It’s interesting that this hemispheric sleep only occurs with non-REM sleep; REM for some reason, requires total brain participation.

Barred Owl, Strix varia

Frigatebirds are amazing seabirds that can stay aloft without landing for up to two months.  They have one major deficit–they cannot swim.  If forced to land at sea they quickly become water-logged and drown.  So curious Niels Rattenborg and others from the Max Planck Institute for Ornithology figured they would be the perfect bird to evaluate for in-flight sleep.

Magnificent Frigatebird, Fregata magnificent     photo by A. Sternick

Rattenborg fastened EEG leads to the skulls of 15 frigatebirds and attached a device to monitor flight speed.  The study confirmed that birds do indeed sleep while flying, but not in the expected manner.  They slept only in short bursts of 10 seconds and only for a total of 45 minutes each day, a much shorter duration than their sleep cycle on land.  They also only used hemispheric sleep while flying, and only slept while gaining altitude in a thermal.  They were completely awake and alert in every gliding descent, perhaps to avoid a lethal crash landing at sea.

Black Skimmers, Rynchops niger

Birds assume many different sleeping positions on land, but I’ve not yet seen one on its back with feet pointing heavenward.  Shorebirds sleep standing up, often on one leg, and usually facing into the wind.  Night herons, owls, and woodpeckers sleep  perched upright.  Their leg muscles in a relaxed state result in a clenched claw, firmly grasping the branch.  Many birds such as the nighthawks sleep horizontally, while some parrots sleep hanging upside down in a bat-like manner.  Many cavity nesters seek out a vacant cavity for the night.

Bonaparte Gull, Larus philadelphia

Birds, like humans, are susceptible to sleep deprivation.  Walker reports that the U.S. government has spent millions investigating the sleep pattern of the lowly White-crowned Sparrow.  If you deprive this bird of sleep during the season it would normally be migrating, it experiences no ill effects.  But similar sleep deprivation at any other time results in catastrophic physiologic brain and body dysfunction.

White-crowned Sparrow, Zonotrichia leucophrys

I’m not sure how they deprived the little bird of sleep; perhaps with bright lights and continuous Barry Manilow songs at high volume.  In any case, this bird has apparently evolved some protective mechanism for sleep deprivation that the U.S. government would love to uncover.

Black-crowned Night-Heron, Nycticorax nycticorax

Have you noticed how difficult it is to sleep the first night in a new hotel and bed?  I now believe this is a throwback to my evolutionary past.  Is there a Sabre-toothed Tiger lurking in the bushes or a Wooly Mammoth lumbering past my cave?  Just like the birds I require safe sleep, but haven’t yet mastered that hemispheric trick.  I guess I need that sentinel goose, standing guard and signaling all is well.

The Flight of Birds; Fair or Foul?

I was minding my own business at the desk by the window when WHACK, a Cardinal crashed into the glass.  I rushed outside to look for a body in the hedge, or at least a stunned bird, but found nothing, not even a red feather.  He must have survived.  It got me thinking about flight.  It’s marvelous and amazing and we terrestrial-bound species are jealous of the birds, but it does come with risks and at a price.  What are the risks and what exactly have the birds given up when they evolved this specialized skill.

Northern Cardinal, Cardinalis cardinalis

I count five groups that have acquired the ability to fly, (omitting the gliding frogs and squirrels).  They are the myriad insects, the extinct dinosaurs–Pterosaurs, the mammalian bats, the birds, and Homo sapiens, since Kitty Hawk.  You must admit that at least with insects and birds, flight has been a successful strategy, with Aves flying around for 150 million years since Archaeopteryx, and insects for even longer.  This compares with a meagre 20 million years for Hominids on earth, with flight mastered by us just 115 years ago.

Brown Pelican, Pelicans occidentalis

There are, of course, obvious advantages of bird flight.  They can get from point A to point B quickly, whether its to find food, escape a predator, or chase a prospective mate.  The destination may just be across the yard or a migration of thousands of miles. Their flying skills include, hovering, take-offs and landings, on either land or water, soaring, gliding, and high speed dives.  They can catch a fly on the wing and even copulate in mid-air.  Very impressive.

Red-shouldered Hawk, Buteo lineatus

There are, however, obvious physical risks to flight.  My office window, multiplied by millions is an example.  Add to that the glass of towering skyscrapers, burgeoning wind farms, and power lines, and you have some real flight hazards.  Fall migration itself takes a huge toll on the young birds.  That’s why the spring migration is less crowded, returning to us just the survivors.

Limpkin, Aramus guarauna

But I’m more interested in the anatomic and physiologic adaptations that have evolved and made flight possible, and what price Aves have paid for this specialization.  The upper extremity of birds has reduced the five digits of its ancestors to three and these serve as the anchors for the primary flight feathers.  The wing is a wonderful and highly specific adaptation for flight, but useless for grasping a tool or playing the piano.  No matter; birds have evolved a flexible neck and versatile beak and tongue to partially offset these deficits.

Rose-ringed Parakeet, Psittacula krameri

What about size?  It does matter for birds.  Flight requires the birds to be relatively small and light.  When you double the length of a bird you increase its weight 8-fold.  Even though the large Golden Eagle only weighs 15 pounds it requires an 8-foot wingspan to fly.

Black Vulture, Coragyps atratus

The physics of flight applies to the birds, just as it did for the Wright brothers.  There must be air flowing over the wing or airfoil to create enough lift to overcome the drag.  Flapping adds greatly to the lift, but weight is still a limiting factor.  Just recall the spectacle of the heavy swan or goose, beating its wings while running across the pond, in its onerous fight to become airborne.

Osprey, Pandion haliaetus

Experts debate how the Pterosaurs and ancient birds “learned” to fly.  One camp suggests a “tree-down” approach, falling or gliding from a height, similar to flying squirrels.  Another group suggests a “ground-up” technique, running or leaping into the air, similar to our struggling swan.  I doubt we’ll ever know for sure.

Laysan Albatross, Phoebastria immutabilis

Birds have also solved the weight issue by their light, hollow bones, ideal for flight but lacking somewhat in strength–another compromise.  “Light as a feather”, the saying goes.  The evolution of the feather figures centrally in the history of flying animals.  Experts now believe feathers evolved long before flight.  Once we pictured dinosaurs as hairless, leathery reptiles, but now learn that some were actually adorned with colorful feathers.  The only question is whether their feathers were for insulation or for sexual ornamentation, but clearly they were not, at least initially, useful for flight.

Belted Kingfisher, Ceryle alcyon

The weight restrictions of flight also require that a bird brain remain relatively small, and surrounded by only a thin skull.  Most of its brain is devoted to eyesight, so highly perfected in raptors, and much of the rest to the regulation of basic functions and the intricate movements of flight.  Although much has been written about the intelligence of birds, (primarily the Corvids), don’t get carried away.  They will not be writing a Beethoven symphony any time soon, or even running for political office.

Prairie Warbler, Dendroica discolor

The warm-blooded, hyperactive, flying birds are massive consumers of energy.  Their high metabolic rates require a never-ending search for food (using energy in the process) for both themselves and their young.  It is a bird’s greatest mission everyday.  The avian respiratory system is also a unique and complicated adaptation of rigid lungs, multiple air sacs, and unidirectional air flow, all designed to supply richly oxygenated blood to meet their high energy demands.

Sandwich Tern, Sterna sandvicensis

It’s interesting that some birds have given up flight completely.  You wonder why.  For Penguins the rudimentary wings are now used for swimming, while the large Ostriches of the savannas of Africa use their downy feathers and wings for shade.  The flightless Dodo birds of the Mauritius Island in the Indian Ocean were doing just fine on the ground until discovered by Dutch sailors in 1598.  The vulnerable bird was easy prey for man and his contaminants and the Dodo is now extinct.  Unfortunately its name has become synonymous with naiveté and stupidity.

Wood Stork, Mycteria americana

So the birds have paid some price for their lives in the sky.  We humans need to keep this in mind as we stretch our frontiers upward, even to the Moon and Mars.  I consider Homo sapiens now a flying animal, similar to the birds.  We are part of nature and not just an outside observer looking in.  Never mind that our “wings” are metal and rivets and computers; they are merely our adaptations, the products of our brains, and our unique ticket to the wonders of flight.

The Wright brothers, Homo sapiens, 1903