(continued) Chapter 3. Long Evolution: Life Emerging
3) Game birds. Wild turkeys, pheasants, quail, guineas, grouse, prairie chickens, ptarmigans, chukars, partridges, wild geese, wild ducks – all rank among hunters’ favorites for the table (though many are destined merely for the taxidermist). Mostly large, all plump and tasty, game birds spend most of their time on the ground, though most can fly quite well when occasion demands. They may be thought “easy pickins” for hunters with shotguns, but they are not. Considerable skill is required in knowing just how to “lead” the frantically-launched game bird before firing, and it all happens within about four seconds. But there is so little need for it in these days of absurdly overstuffed supermarkets…
I remember the lean years of the Second World War, when beef and pork were among the many things – such as tires, sugar, batteries, shoes – strictly rationed in support of the war effort. Ration stamp booklets were issued to both adults and children – I still have some of mine. Between 1941 and 1945 commercial meat virtually disappeared from the stores, so the occasional rabbit, squirrel or game bird brought in by my father’s shotgun was a rare treat to be savored – taking caution not to break a tooth biting down on a lead BB. On wintry mornings before school, bundled to the eyes against the never-ending prairie wind, I walked my two-mile circuits around the fields frozen hard as stone in hope that a rabbit had been lured into one of my box traps by the slice of apple bait inside. Privation was real for the home folks during those years, a new normal willingly faced in nervous certainty that our troops, the good guys, would prevent German and/or Japanese invasion of America – and many were the homesteads that raised big gardens, chickens, a hog or calf, rode a bicycle to buy milk fresh from the farm up the road. That was then, this is now – our supermarkets seem to contain too much, far more than we could possibly need for “adequate,” and I prefer to watch these beautiful “game” birds rather than eat them.
4) Tropical birds. The hundreds of tropical bird species include some of the most beautifully colored in the world – flamingos, parrots, cockatoos, macaws, keas, lorikeets, toucans and more. Many equipped with large, strong beaks that can crush the hardest nut shells, they include some notably inquisitive and intelligent birds. The African gray parrot named Alex lived thirty years and was the subject of a three-decade study by his owner, animal psychologist Irene Pepperberg. Her intimate work with Alex dramatically confronted scientific mindsets conventionally “certain” that birds lack intelligence, dogmatically assuming that only large primate brains can handle the complexities of language, syntax and understanding. Pepperberg’s work established the ability of some bird species to reason and display creativity on a level comparable to apes, dolphins, and – at the time of Alex’s death – a human child between two and five years old.
Native tropical birds are joined annually by many common North American songbirds that migrate south to overwinter from central America to the Amazon rainforests. The albatross – a long lived but now-endangered species – is also a tropical native as well as a seabird, looking a bit like a designer-combined hybrid of pelican, parrot and gull.
5) Wading birds. Flamingos, herons, ibises, cranes, spoonbills, storks, egrets, terns, plovers, curlews, snipes and sandpipers – all are good representatives of wading birds naturally adapted to aquatic environments. Showing great variety in leg length (small to tall), body size and shape of beak, wading birds breed on land but live their lives wading in – or keeping a close eye on – water habitats such as saltwater shores, the shallow edges of rivers, lakes and ponds, and, especially, shallow marshes and swamps. These wetlands, periodically or perennially flooded, have been consistently drained and converted to agricultural, residential and commercial land uses throughout American history. More than half the nation’s original wetlands – up to ninety percent in some states – have been lost through drainage and conversion, in direct consequence of which populations of wading birds that depend on these rich habitats have suffered plummeting declines. These bird populations, though protected in selected areas, continue to fall as habitats continue to be destroyed.
With bills adapted to probe mud and animal burrows, wading birds are opportunistic feeders able to consume a great variety of the creatures found in wet habitats such as fish, amphibians and reptiles, crustaceans, plant seeds and small mammals. Many feed standing in less than twelve inches of water, sharp bills at the ready to spear lunch. I have observed a small blue heron to spend hours perched on a limb ten feet above our small front pond, head cocked and patiently alert to slipup by an unwary tasty frog. Most wading birds are migratory.
6) Water birds. Not an exclusive category, water birds are so called because they depend on aquatic habitats in some or all parts of their life cycles. Also called “aquatic birds,” they include species that variously overlap into other categories such as sea birds (penguins, gulls, pelicans), tropical birds (flamingos) and wading birds (storks, herons). Some carnivorous birds take prey mainly from water (ospreys, sea eagles), but are not considered water birds. Our attention here accordingly goes to a few in the waterfowl family Anatidae which undeniably qualify as water birds and are most familiar to most readers: ducks, geese and swans. All three are related – and sometimes confused with unrelated species exhibiting similar bodily forms such as loons, grebes and coots. Anatidae have broad bodies with webbed feet adapted to efficient swimming (rather than wading) and – perhaps uniquely among aquatic birds – the classic flattened tapering beak adapted for foraging on rich underwater bottoms.
Ducks, the smallest members of the family, come in approximately a hundred species worldwide, and have been domesticated for millennia as a source of eggs and meat. Fully able to feed themselves shortly after hatching, ducks eat mainly seeds, leaves, small fish and shellfish. Most males mature to beautifully colored patterns, females have subdued mottled coloring.
Geese spend much of their lives on land though they are fully adapted water fowl and are classified as such. Two broad types include Anser geese (gray, orange or pink legs and serrated bills) and Branta geese (dark gray or black legs, unserrated black bills). Baby geese are called goslings, a group of geese is a gaggle. They can live up to twenty-five years. Geese are grazers, spending much of their days foraging mainly on leaves and grass, preferably close by a body of water where they also forage. A child’s singing rhyme informs us that the goslings are mourning because Aunt Rhodie must be told that her old gray goose died in the millpond from standing on her head.
Swans, the largest of the family Anatidae, may live up to 35 years, weigh over thirty pounds and achieve wingspans over ten feet. They pair for life, though a widowed swan may take a new mate. Most are solid white though there are some dramatically black species. Young swans are cygnets, adult females are pens, adult males are cobs. In legend and regard, swans are compelling as one of the world’s most graceful birds, a fact immortalized in Tchaikovsky’s beautiful ballet Swan Lake.
7) Sea birds. Defined as birds that have adapted to marine habitats, these avian saltwater lovers come with waterproof feathers, webbed feet and sharp beaks. Good representatives of sea birds include puffins, shearwaters, kittiwakes and gulls – though the tribe’s indistinct boundaries also reach out to penguins, fulmars, whalebirds, boobies, gannets, auk and auklets, murres and murrelets, dovekies, razorbills, guillemots, terns, pelicans, some ducks and geese, and the Galapagos Waved Albatross which is thought to be the largest among them all across the earth’s seas. Sea birds also are good representatives of convergent evolution because, although varying greatly in physiology and behavior, they have mutually adapted in similar ways to similar ocean environments and feeding niches.
And as any beachcomber knows, there are lots of them – gulls alone present forty-eight species worldwide, from the regal Great Black-backed Gull (2.5-foot length, five-foot wingspan) to the “little” Hydrocoloeus minutus gull less than a foot long. Kittiwake gulls outrank most other gulls for time spent at sea, coming onshore only during the breeding season when nobody wants to get left out. Kittiwakes are in turn outpaced by Manx Shearwaters (not a gull) which may remain aloft across ocean waters for weeks on end and cover up to three hundred miles a day. These are most misleadingly named (Puffinus puffinus) because they are wholly unrelated to puffins which are members of the auk family, their only resemblance being a preference for nesting in burrows on land.
Most sea birds, especially gulls and pelicans, spend a lot of time catching fish or going after the voluminous fish garbage dumped back into the drink by floating fish factories. This latter practice has in turn produced an industry of compassionate environmentalists who spend a lot of weekends freeing sea birds from shredded fishing net and removing fish hooks from their throats. This problem fortunately may be decreasing with the advent of ships such as the Lafayette, the world’s largest floating fish factory, owned by the multi-national corporation Pacific Andes Group. This $100-million mother of all fishing boats – 750 feet long by 105 feet wide – acts as processing central for a satellite fleet of five super-trawlers and seven other fish-catcher vessels which enable the Lafayette to process, freeze and ship one thousand five hundred tons (tons) of fish a day. The solid wastes that lesser fish factories dump back into the briny (i.e., fish heads, skin, viscera, bony carcasses) can be processed onboard the Lafayette into fishmeal so that every last fin is utilized and nothing fails to turn a profit. But this too may change, as Pacific Andes Group has filed for bankruptcy blaming El Nino and unfair treatment by financial mega-lenders. Overall impact on sea birds and fish extinction is unclear, however, for Pacific Andes Group is only twelfth-largest among international seafood corporations.
8) Night birds. Night birds are active during darkness when almost all other birds sleep, and their adaptations to nocturnal hunting are remarkable. For example, the South American oilbird is unique in its bat-like ability to roost in dark caves by day and to use echolocation at night. Unlike bats and other night birds, however, its night feeding consists exclusively of fruit. Owls, with about 150 species around the world, are probably the best known nocturnal birds, though nighthawks (e.g., whippoorwills, nightjars) are among several others active only at night. Each season’s return of warm nights brings a great horned owl’s distant but assertive HOO-HOO, a’HOOT through my bedside window. More often heard than seen, owls are predators with special adaptations for nocturnal lives. They are adept at silent flight, and their large eyes have keen vision for judging distances when hunting at night. With feathers colored to blend into background branches of trees and other favorite roosts, they are difficult to spot by day.
They are aided in finding prey by soft feather tufts that stick up like ears. Asymmetrical placement, shape and size of these “owl ears” produce an effect similar to binocular vision. One ear, higher than the other, hears sounds from a “higher point” so that the other hears from “a lower point,” thus enabling the owl to pinpoint the direction and location of revealing noises made by unwary prey. Thus uniquely equipped, owls can hunt by sound alone and easily capture small animals hidden beneath snow or leaf litter. This auditory advantage is supplemented by another even more sophisticated – a “facial disk” of feathers which surrounds their heads in a forward-facing pattern that collects and funnels sound to real ears hidden beneath the feathers. Exceedingly adept carnivores, owls eat rats, mice, voles and shrews; rabbits, squirrels lemmings and skunks; grasshoppers, insects, spiders and scorpions; fish, snakes and reptiles; and other birds including smaller owls. One owl may catch and consume an estimated two thousand rodents a year.
9) Flightless birds. The wings of several bird families have evolved – or devolved, according to your view – to variously shaped appendages no longer able to fly. Emus, ostriches and penguins, for example, all have wings but do not fly. The African ostrich, the world’s largest bird, can stand well over six feet tall at maturity and give a racehorse a good run at speeds up to 40 miles an hour. Australian emus are nearly as fast. Others have adapted to the water and use their wings to swim instead of fly. Penguins attain speeds of only nine miles per hour, but they do so while swimming. Well adapted to life in water, penguins have short legs with webbed feet, plump seal-like streamlined bodies, and flattened wings they use effectively as flippers. Awkward as upright waddlers on land, penguins are graceful swimmers able to dive deeply when hunting for fish and krill. The world’s smallest flightless bird – the Island Rail Bird – lives on an inaccessible island in the South Atlantic, weighs slightly over an ounce and is the size of a small tomato.
The Bottom Line: all these thousands of bird species can be genetically traced back, and back – back through the twigs and branches and limbs of countless thousands of generations over the millennia of long evolution, a many-braided stream – to a single bird-like creature, the ancestor common to them all.
So there it is. With the fishes, amphibians, reptiles and birds all duly recognized, that’s all the vertebrates except…drum roll…us mammals. We built up properly, pausing to look over the boring prokaryotes, the boring archaea, even the boring other eukaryotes in our own line of evolutionary ascent. Dues paid to all those others on the vast phylogenetic tree of life, we can now move on out to our solitary little twig and, with intense interest, examine that two percent or so of the tree which contains – ahem – the most complex creatures ever to evolve on the planet we higher animals call earth. Our kind. Mammalia.
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…to be continued in one week…
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