Sunday, June 26, 2016

Fish Crow at Eagle Bluffs

While surveying a large pool at Eagle Bluffs Conservation Area this morning, I heard a familiar call that echoed from over my left shoulder.  Turning to locate its source, I saw a crow flying across an open marsh, being chased by a trio of red-winged blackbirds.

The crow's call reminded me of lazy afternoons on the seawall at Longboat Key, Florida.  Indeed, this was a fish crow, more often associated with southern coasts but now increasingly common along the larger rivers of the eastern and central U.S.  Like their widespread cousin, the American crow, fish crows are omnivores, feeding on waste grain, berries, seeds, insects, bird eggs, stranded fish, small lizards, small mammals, carrion and human food waste; in fact, they are among the most relentless predators of eggs and nestlings at heronries and sea bird rookeries.

Distinguished from American crows by their slightly smaller size and distinctive, higher-pitched "nasal" call (contrasting with the harsh, raucous voice of their widespread cousins), fish crows generally gather in large flocks and move toward coastal estuaries during the colder months.  Until then, I and my birding colleagues along the Missouri River will lend an ear to their presence and enjoy a bit of audio from the coast in the American Heartland.

Friday, June 24, 2016

Flooding in Appalachia

Yesterday afternoon and evening, a line of strong thunderstorms stretched across the Appalachians, from the Ohio River Valley to south-central Virginia.  Aligned along a stationary front and steered by the jet stream, the storms "trained" over the same areas, unleashing torrential rain (up to 9 inches in some locations).

Falling on the dissected terrain of the Appalachian Plateau and the Ridge and Valley topography west of the Blue Ridge, the copious precipitation drained rapidly from the steep ridges to the primary river valleys; mudslides and valley floods were the result, most severe in southeastern West Virginia and adjacent sections of Virginia.  Unfortunately, most Appalachian towns lie within the valleys and widespread damage has been reported.

Flash flooding is especially dangerous in mountainous terrain since it develops rapidly and escape routes are often limited.  Those living in or visiting such regions are thus advised to heed weather forecasts and take note of potential routes to higher ground; multiple routes should be considered since some roads may be closed due to high water or mudslides.  Beautiful as it may be in sunny weather, mountainous terrain poses unique risks when thunderstorms approach, even when heavy rains fall far upstream.


Thursday, June 23, 2016

Chat Alley

At South Platte Park, in southwest Metro Denver, a trail meanders along a low ridge on the west side of Eaglewatch Lake.  Winding through a landscape of shrubby meadows, lakeside woodlands and groves of cottonwoods, this trail is one of the better avenues for observing woodland songbirds in the south Metro Area.

During the warmer months, yellow-breasted chats are especially common here, delivering their endless sermons from woodland pulpits, their colorful vestments glowing in the bright morning sun; I observed seven of them today, spaced along the ridge.  Other common summer residents include gray catbirds, broad-tailed hummingbirds, yellow warblers, Bullock's orioles, western pewees and house wrens; among the permanent residents are great horned owls, Cooper's hawks, northern flickers, cedar waxwings and black-capped chickadees and this lakeside ridge is a magnet for migrant warblers, vireos and other songbirds (e.g. western tanagers) that stop to rest and feed on their way to the mountains.

In addition, the "chat alley" trail offers broad views of Eaglewatch Lake, which attracts double-crested cormorants, American white pelicans, ospreys, bald eagles, western grebes and a wide variety of waterfowl in the course of the year.  The chats may steal the show on summer mornings but this lakeside ridge has much to offer in any season; the trail is best accessed from parking areas near C-470, via the southern Park entrance from Platte Canyon Road.

Wednesday, June 22, 2016

An Incessant Songster

Working on our Littleton farm this morning, I was serenaded by the calls and songs of many avian residents and visitors.  Dominating this background noise was the incessant song of a male lesser goldfinch, delivered from prominent perches throughout the property.

Arriving along the Colorado Front Range in late April or May, lesser goldfinches initially maintain their gregarious habits, roaming about to feed in weedy fields, across foothill shrublands or on the sunny slopes of lower canyons.  By late June, males begin to establish their territories, announcing that intent with long soliloquies of high pitched notes and whistles designed to attract a mate and keep other suitors at bay.

Like other species of goldfinches, lessers nest in mid-late summer, when the seeds of thistle and sunflowers are most abundant.  Once the young are fledged, these small, attractive songbirds congregate in large flocks once again, heading for the Desert Southwest, South Texas or Mexico before chilly autumn winds rake the Front Range.


Tuesday, June 21, 2016

A Mulberry Bonanza

It's a good year for mulberries along the Colorado Front Range.  Indeed, the mulberry trees on our Littleton farm are loaded with fruit, attracting a wide variety of wildlife.

American robins and house finches are the primary consumers, clogging the trees for most of the day; less common visitors include cedar waxwings, Bullock's orioles, spotted towhees and gray catbirds and wandering opportunists such as magpies and starlings.  Raccoons and skunks feed on fallen fruit as do red fox and coyotes that hunt on the farm.  While the red fruit on the weeping mulberry is sweet, we humans are not generally fond of the tart, white mulberries on the larger trees.

Of course, there is a drawback to this mulberry bonanza.  Two of the trees sit close to the house and, unfortunately, near the two entrance doors.  Despite the best efforts of our avian residents, most of the fruit ends up on the ground, on the roof and in the gutters; those that litter the entrance walkways are most problematic, requiring regular cleanup to keep squashed mulberries off the soles of our shoes and out of the house.

Monday, June 20, 2016

Cool Down in Denver

After two weeks of hot, humid weather in Missouri, I returned to Colorado today and was greeted by a cold front.  As I approached Metro Denver, a thick band of clouds was moving south toward the city and the Front Range peaks were obscured by an upslope haze.

By the time I reached our Littleton farm, scattered showers and thunderstorms had formed above the urban corridor and the air temperature, thanks to the upslope flow, had dropped to 70 degrees F, a welcome change from the sunny, hot conditions on the Great Plains.

As I write this post, it is 65 degrees at the farm and skies are clearing behind the cold front.  To our south, however, a swath of thunderstorms stretches along the Palmer Divide and into the foothills north of Pike's Peak.  One of the storms, located near Wilkerson Pass, west of Colorado Springs, has become severe and radar indicates that it has spawned a tornado.  The storms will likely weaken as the sun sets and our cool reprieve will be brief; if the current forecast is accurate, we can expect high temperatures near 100 degrees F in the Front Range cities tomorrow afternoon.

Sunday, June 19, 2016

Life & Energy

Life, whether in the form of a single-celled organism or a human being, might be defined as the capacity to harness energy for the purposes of constructing and maintaining vital tissues and sustaining metabolic processes.  From the moment of conception (or budding in asexual life forms), energy must be acquired or generated to permit survival; depending on the organism, it is needed to fuel growth, cellular diversification, physiologic processes and mobility.

Bacteria and other unicellular organisms are able to "ingest" nutrients through their cell walls while photosynthetic algae and plants utilize solar energy to fuel their metabolism and growth.  Fungi recycle nutrients from decaying plants and animals and some deep sea invertebrates feast on bacterial mats that form on the flanks of sulfide-spewing hydrothermal vents.  Complex marine, freshwater and terrestrial food chains consist of producers (plants or algae), primary consumers (herbivores) and secondary consumers (carnivores); of course, a series of carnivorous activity leads to the top predator in each chain (e.g. mosquito, dragonfly, frog, snake, hawk).

Energy flows through these food chains, stored for periods of time in certain tissues (fat, glycogen, starch, bulbs) but eventually recaptured by scavengers and fungi when injuries, illness, predation or natural aging lead to the death of plants and animals.  Prior to death, living organisms transfer energy to the environment via heat production and in the organic waste that they produce; they may also lose vital nutrients to parasites.  While this cycle of energy and life is easily observed and readily accepted in nature, we humans often reject the fact that our own lives, from conception to death, reflect this universal process.  We are, in fact, transient conduits of energy.

Saturday, June 18, 2016

Social Dysfunction & Mass Murder

Once again, as details emerge about the tragedy at the Orlando nightclub, we learn that the killer had a troubled childhood and that he was expelled from college and fired from jobs due to violent behavior or threats.  It also appears that he may have been plagued by the guilt of homosexuality (stemming from his religious faith) and that his relationships with women involved domination and domestic violence.

In most past cases of mass murder, we learned that the male perpetrators came from a dysfunctional household, endured abuse from an alcoholic father, failed to establish normal social relationships or demonstrated symptoms of mental illness.  After the tragic event, family members, friends or colleagues recount the warning signs that they observed but did not or could not intercede beforehand.

Focused on international terrorism, Conservative Republicans place emphasis on a military solution, campaigning to beef-up a Defense Department that already consumes a massive portion of our Federal budget.  But while some of the killers may have been influenced by terrorist propaganda, they were already primed by social factors that we do not adequately address.  Sensible gun laws are certainly part of the solution but early childhood daycare, after-school activities, job training, troubled teen programs and an effective mental health care system all need to be adequately funded.  Unfortunately, the same politicians that favor increased military spending and oppose sensible gun control measures also want government out of our lives and refuse to support such vital programs.

Friday, June 17, 2016

Antares

For those of us in the Northern Hemisphere, Antares is one of the brightest stars in the summer sky.  A component of the Constellation Scorpio, it shines from the southern sky; in mid June, it's reddish image can be seen to the SSE at 10 PM and was just below the moon last evening.

Like its winter counterpart, Betelgeuse (in Orion), Antares is a super red giant; if placed at the location of our sun, its outer surface would lie between the orbits of Mars and Jupiter (i.e., the four inner planets of our solar system would be swallowed by its mass).  Antares is about 520 light years from Earth; though it is among the 20 brightest stars in the night sky, it would be far brighter if the majority of its radiation was not in the infra-red spectrum (and thus not visible to the human eye).

Super red giants are stars in the latest stage of their life; when they eventually collapse, a black hole is thought to form and their energy is released as a supernova, spawning the birth of many new stars.  Since Antares is 520 light years away, it may have exploded into a supernova 500 years ago and we won't know until 2036; in other words, the light that arrives from Antares today left the star about the time that Columbus left for the New World.

Thursday, June 16, 2016

Summer Pelicans at Eagle Bluffs

American white pelicans breed on lakes across the Northern Plains and Great Basin of North America.  Come autumn, they migrate southward, often using staging areas along the way.  Pelicans that breed east of the Rockies generally winter along the Gulf Coast or lower Mississippi Valley while Great Basin pelicans head for the Central Valley of California, the Salton Sea, or coastal bays of Southern California and Mexico.  Some permanent, non-migratory colonies inhabit Florida, Texas and Mexico.

American white pelicans are not sexually mature until their third year.  Some of the young, non-breeding birds stay on their wintering grounds for the first two years while others migrate northward with the adults.  In either case, non-breeding white pelicans tend to wander about during the summer months and may turn up at attractive feeding sites throughout much of the U.S.

Indeed, a flock of American white pelicans has been present at Eagle Bluffs Conservation Area, in Central Missouri, over the past week and, as of this morning, their number had increased to 67.  While this summer flock is rather large (based on my experience), the total population of white pelicans has been steadily increasing over the past 50 years due to DDT elimination, hunter education and favorable habitat development (i.e. fish-stocked reservoirs).  It is thus likely that summer flocks of these magnificent birds will become increasingly large and widespread in the future (unless global warming decimates their breeding and fishing lakes).


Wednesday, June 15, 2016

Within the Dome

A massive atmospheric ridge of high pressure extends across much of the U.S., stretching from Southern California to the Mississippi Valley.  Within this dome, air is sinking, causing it to heat up and dry out; as a consequence, cloud formation is minimal, augmenting the intensity of the high June sun.

High temperatures will range from the mid 90s (F) to 120 degrees within the dome; the most extreme heat will develop in the low deserts of the Southwest while triple digit heat indices (combining temperature and dew point) will be widespread across the Great Plains and lower Mississippi Valley.  Here in central Missouri, we expect a high of 99 degrees F under sunny skies and anticipate afternoon highs in the mid to upper 90s for the next week.

Thunderstorms will erupt along the northern and eastern edges of the dome, where the hot, humid air interacts with a cooler and drier air mass; this clash zone currently stretches from the Great Lakes to the Ohio River Valley and Mid Atlantic Region.  On the back (northwestern) edge of the dome, a less intense band of precipitation curves from Northern California to Montana.  As the atmospheric ridge inches eastward, the storms will move in concert and relief from the intense heat won't arrive for a week or more.  By July, such high pressure domes begin to settle over the Southern Plains, triggering the Southwest Monsoon.

Sunday, June 12, 2016

Lark Sparrows

Lark sparrows are summer residents of the American Midwest, Great Plains and Great Basin; found primarily west of the Mississippi River, their range extends into southern Canada, across eastern portions of the Pacific Northwest and throughout lower elevations of California.  During the colder months, they head for the Desert Southwest, South Texas, the Gulf Coast region, Mexico and Central America.

The only member of their Genus, lark sparrows sport a striking facial pattern of white, black and chestnut-brown stripes, a white breast with a central black spot and a white edge at the end of their long tail; the latter edge, thicker laterally than centrally, is a good field mark for novice birders.  These handsome sparrows favor open grasslands with scattered shrubs or trees and are often found along country roads where they scour the gravel for insects and seeds.  When threatened, they often escape to dense vegetation rather than taking flight.

Lark sparrows seem to be more abundant at Eagle Bluffs Conservation Area (in central Missouri) this year but this may merely reflect a personal familiarity with these grassland birds that inhabit both of my home States.  Regardless, it's always good to see them as spring turns to summer.

Saturday, June 11, 2016

Chigger Season

To the dismay of farmers, gardeners, campers, hikers and music festival attendees, chigger season is underway across the American Heartland.  Chiggers are the larval forms of a mite that favors pastures, fields, grasslands and lawns, especially in warm, humid areas; the female mite lays her eggs on vegetation which hatch to release the larvae.  The latter feed on skin cells of mammals (humans included) before maturing into nymphs and then adults.

Chiggers feast on the skin cells by injecting an enzyme that breaks down the cellular structure, allowing the larvae to ingest nutrients; these "bites" trigger an inflammatory reaction, producing red bumps or welts that appear 24-48 hours after the infestation.  As many of us know, this rash is extremely pruritic if not painful; the intense inflammatory response generally fades within a few days.

Those who venture into chigger habitat are advised to shower and wash their clothes in hot water as soon as their activity is completed; of course, this is not always possible for campers and festival attendees.  For those "bitten" by chiggers, cool compresses, anti-inflammatory meds (e.g. ibuprofen) and anti-pruritic agents (e.g. diphenhydramine, topical hydrocortisone) are recommended; avoid excessive scratching which can lead to secondary bacterial infection.  Fever, expanding redness or pustular drainage are signs of infection and warrant medical attention.

Thursday, June 9, 2016

A Stranded Duckling

Over the past two decades, I have made hundreds of visits to Eagle Bluffs Conservation Area, in Central Missouri, and have never failed to be inspired by its beautiful landscape and superb diversity of wildlife.  But nature offers both beauty and tragedy and, this morning, I was dismayed to observe a stranded duckling, swimming along the marshy edge of a floodplain pool.

The young wood duck may have prematurely left its nest box; however, he appeared well-developed and his siblings would surely have followed.  Perhaps he became separated from his mother and her brood but wood duck moms are very attentive.  This leaves the possibility that his mother was killed and that he is the sole survivor of her brood, the others picked off by water snakes, snapping turtles, great blue herons, mink, coyotes or bald eagles.

Few animals are as cute as a duckling and many humans would be inclined to rescue this youngster.  Naturalists, however, understand that it is best to minimize our impact on nature and that her cycle of life includes the death of young creatures.  A stranded duckling, sure to die without the guidance of his mother, is vital to this fabulous ecosystem, as important as the majestic eagles that survey its realm.

Wednesday, June 8, 2016

Excusing Racism

It is both sad and deeply disturbing that most prominent Republicans continue to back the candidacy of Donald Trump despite his overt racism.  Suggesting that Trump, flawed as he may be, is a better choice than either the Democratic or Libertarian nominee, they are all-too-willing to excuse his racist remarks as missteps by an inexperienced politician.

Racism is not a misstep.  It cannot be explained away.  Rather, it reflects both Trump's deep-seated beliefs and his conviction that such remarks appeal to his white, uneducated base.  Continuing to support their bombastic, narcissistic nominee, the Republican Party is willing to condone racism in order to gain control of the Executive Branch; after all, that is what they need to shrink the Federal Government, curtail environmental regulations and place conservative-minded judges on the Supreme Court.

Hopefully, educated Americans will join minority groups across the country to derail the exploits of King Trump.  Despite his apparent willingness to commit political suicide, the Republican elite won't cast him aside; the "Party of Lincoln" is nominating a racist for President of the United States.

Tuesday, June 7, 2016

The Other Oriole

On this cool, sunny morning, an excellent variety of birds were moving about Eagle Bluffs Conservation Area, on the Missouri River floodplain; within 2 hours, I had observed 43 species.  Among these were a fair number of orchard orioles, the first I have seen this year.

Unlike their well-known Baltimore cousin, the male orchard oriole sports dark, rust-colored plumage, set off by a black head, chest, tail and wings.  Though a fairly common summer resident throughout the central and eastern U.S., it does not generally arrive until late spring and often leaves for wintering grounds (in Central and northern South America) by August.  Like most orioles, orchard orioles build a pouch-like nest that is suspended from a forked, distal limb of a shade tree; unlike most species, it is a colonial nester, often tolerating the close presence of other birds as well.

Orchard orioles prefer open woodlands, especially along streams.  While their name suggests a fondness for fruit, they feed primarily on insects during the summer months, snaring prey from vegetation or directing from the ground.  They do supplement their diet with berries, however, and, on their wintering grounds, consume the flowers and nectar of some tropical plants, playing a significant role in their pollination.

Sunday, June 5, 2016

Glacial Lake Modoc

During the cool, wet climate of the Pleistocene, a large lake formed east of the Cascades in southern Oregon and northeastern California.  Known today as Glacial Lake Modoc, it had a surface area of 1100 square miles; its surface was 100 feet higher than that of Upper Klamath Lake, its largest remnant. Tule Lake and Lower Klamath Lake and their adjacent wetlands are also remnants of Lake Modoc, which extended eastward along the Lost River Valley and northward along the Wood, Williamson and Sprague Rivers that now feed Upper Klamath Lake.

Current geologic evidence suggests that the Upper Klamath Basin formed as a vast graben, divided by north-south trending fault-block ridges.  Glacial meltwater from the Cascades balanced outflow through the Klamath River which carved a spectacular canyon through the Northern Coastal Ranges of California to reach the Pacific.

Toward the end of the Pleistocene, as the climate warmed, the mountain glaciers retreated, inflow to Lake Modoc diminished and the lake level fell, exposing vast wetlands between the remnant lakes.  Of course, once European settlers colonized the region, wetlands were drained, rivers were dammed and tributaries were diverted for irrigation, producing the landscape that we find today.  Fortunately, some recovery has occurred with the establishment of the Lower Klamath, Tule Lake and Clear Lake National Wildlife Refuges and spectacular congregations of migrant waterfowl and shorebirds still visit the Basin.

Saturday, June 4, 2016

The Asian Carp Invasion

On my walks around Landen Lake this week (a small suburban lake north of Cincinnati), I have been repeatedly reminded that the Asian carp invasion is a significant problem throughout the Mississippi River watershed.  Introduced in the 1970s to control aquatic vegetation and to filter sewage water, they escaped containment areas during floods and have spread throughout most of the U.S.  Favoring shallow, sluggish waters, they often attract our attention as they thrash about, their dorsal and tail fins breaking the surface.

Represented by four species (grass, black, silver and bighead carp) these large fish are very prolific and soon dominate the aquatic ecosystems that they colonize; black carp, which feed on mollusks, threaten native snail, mussel and clam populations while the others reduce the availability of plankton and vegetation vital to native fish, amphibians and aquatic reptiles.  As video enthusiasts know, silver carp also pose a threat to boaters, jumping into the air (and into boats) in response to the sound of outboard motors.

Concerned that Asian carp will enter the Great Lakes and disrupt the ecology of their fisheries, efforts have been made to block carp migration along canals that connect those Lakes with streams of the Mississippi watershed; "electric fences" have been used with some success but carp also spread as eggs or fingerlings on boat hulls, via the use of live bait, during floods and perhaps even on the legs of wading birds.  Taking advantage of the carp bonanza, some companies are culling them to produce pet food or fertilizer; vultures also partake of the bounty, feasting on dead carp that were stranded by shrinking lakes or rivers.

Thursday, June 2, 2016

Western Heat Wave

Intense heat is beginning to develop across the Desert Southwest and will spread northward through the Great Basin and Central Valley of California; before it's over, the Pacific Northwest will also be enveloped in the swath of hot air.

The culprit is an atmospheric ridge, a northward bowing of the jet stream along the outer rim of a high pressure dome.  Within the ridge (beneath the dome), sinking air heats up and dries out and cloud formation is impaired; Santa Ana winds may also develop in Southern California.  Triple-digit heat is forecast for much of the region, with upper 90s (F) expected in Oregon and Washington.  Meteorologists warn that the high pressure ridge will remain in place through the upcoming weekend.

As one might expect, the Western heat wave is tied (meteorologically) to the Texas floods.  East of the ridge, the jet stream dips southward and this trough has spawned an upper level low over central Texas.  Counterclockwise winds around the low are combining with clockwise winds around a high pressure dome over the Southeast, pulling copious Gulf moisture across East Texas, Louisiana and the lower Mississippi Valley.  Once this atmospheric pattern shifts eastward, the flooding rains in Texas will cease and the Western heat will abate.

Wednesday, June 1, 2016

Brazos River Flooding

The Brazos River forms on the Llano Estacado at the junction of its Salt and Double Mountain Forks, northwest of Rule, Texas; it then flows northeastward to Seymour before angling southeast toward the Gulf of Mexico.  En route to the Gulf, the river passes through three major reservoirs: Possum Kingdom Lake, Lake Granbury and Lake Whitney; it also flows through Waco, passes west of College Station and flows west of Houston before emptying into the Gulf of Mexico at Freeport, Texas.

While the Brazos itself is 840 miles long, its watershed stretches back to eastern New Mexico; from its most distant tributary to its mouth, the River's watershed is 1280 miles in length, making it the 11th longest stream in the United States.  Over the past few weeks, heavy rainfall across the Brazos watershed has led to severe flooding, especially below the above mentioned reservoirs.  Not designed for flood control, these lakes must be partly drained as they fill in order to prevent catastrophic dam collapse.

As of this morning, the Brazos crested at 54.6 feet in Richmond, Texas (southwest of Houston), shattering a Century-old record by almost 4.5 feet; unfortunately, more rain is forecast across the watershed in the coming days.  To date, at least 6 individuals have been killed by the flooding and 31 Texas Counties have been declared disaster areas.  See also Texas: Land of Drought & Flood.

Tuesday, May 31, 2016

Eulachon

Eulachon are small marine fish (8-9 inches in length) that feed on plankton in the eastern Pacific, from Alaska to northern California.  In late winter, they move into estuaries and coastal rivers to spawn; most adults die after this process.  Fertilized eggs, which sink to the gravel beds, hatch in a month and the fry head to sea; there they will live in offshore waters for 3-5 years before returning to spawn.

Heavily laden with fat, the spawning eulachon are known as candlefish (since dried specimens can be lit like candles) and were called "salvation fish" by Native Americans of the Pacific Northwest since their calorie-rich bodies provided vital nutrition during the leans months of late winter and early spring.  Of course, Steller's sea lions, dolphins and sea birds also welcome their spawning runs.

Unfortunately, eulachon have all but disappeared from the coastal rivers of northern California, Oregon and Washington and their numbers have decreased significantly farther north.  Global warming, overfishing, water pollution and altered river sediments (due to hydroelectric dams) are all thought to be playing a role in the population decline of this smelt.

Monday, May 30, 2016

Tragedy at the Zoo

Throughout my formative years, I was enamored with animals of every kind and visited zoos on a regular basis; in my mind, despite their use of restrictive cages, zoos played an important role in public education and wildlife conservation.  The increasing use of "naturalized enclosures" allayed some of my concerns and I planned to pursue veterinary medicine long before I opted for medical school.

The zoo of my youth was the Cincinnati Zoo, where yesterday's tragedy unfolded; a four-year old boy somehow gained access to the gorilla exhibit and fell into the moat.  This caught the attention of a 17 year-old male gorilla who grabbed the child (perhaps with protective rather than hostile intent), forcing staff members to kill him.  While the cause of this tragedy is under investigation, inadequate fencing and inattentive parenting both surely played a role.

In a larger sense, this tragic event highlights both the potential risks and ethical dilemmas of caging intelligent creatures (primates, elephants, cetaceans, etc.) for our own entertainment, even if a certain degree of education and research is achieved.  The concept of rescuing endangered species for captive breeding and reintroduction to the wild has been unsuccessful in most cases (California condors and black-footed ferrets are two exceptions) and "naturalized exhibits" can never match the freedom and benefits of native habitat.  Though tragedies such as occurred yesterday are rare, the greater tragedy of human-imposed captivity has long been a cherished practice in our culture.  Perhaps, as human enlightenment progresses, we will come to reject the imprisonment of intelligent animals.