DESCENDANT SPECIES
Golden toad – Bufo periglenes
The golden toad, native to Costa Rica’s famed Monte Verde cloud forest, has not been seen since 1989. Often depicted in travel brochures and advertisements, it effectively symbolized the richness of tropical biodiversity. In the late 1980s herpetologists began noticing fewer and fewer of this high-profile species. What was first noticed by local researchers ended up being a worldwide phenomenon: amphibian populations have been in sharp decline since the mid-1980s. Because amphibians breathe through their skin, they are particularly sensitive to both water and ground pollutants. Global warming, increased UV levels, toxic chemicals, and general habitat degradation have all been suggested as causes for their reduced numbers. It is now known that amphibians are dying from a worldwide epidemic of fungal disease caused by Batrachochytrium dendrobatidis, which makes amphibians more vulnerable to all of these factors.
’I’iwi– Vestiaria coccinea
One of Hawaii’s 50 or more species of finchlike honeycreeper, the ’i’iwi was once found on all the main islands of the Hawaiian archipelago. Now only a few isolated groups remain. The elegant sickle-shaped bill of the ’i’iwi evolved to allow it to take nectar from the downwardly curved flowers of the many native lobelias. Introduced plants and animals, as well as human cultivation and clearing, have had a devastating effect on these flowering shrubs and trees, and many of them are now gone. Like other Hawaiian birds, the ’i’iwi has been hit hard by deforestation, the predation of domestic cats and rats, and mosquito-borne disease. The whole Hawaiian island chain was mosquito-free until 1826, when a few sailors from the British ship Wellington emptied some larva-infested water barrels into a stream on Maui.
Presidio manzanita – Arctostaphylos pungens var. ravenii
Peter Raven, director of the Missouri Botanical Garden in St. Louis, discovered a lone example of this subspecies in the Presidio of San Francisco in 1952 when he was just 16 years old. Today there are a number of clones of this ground-hugging shrub growing near the parent plant and in several suitable botanical gardens. Sheltered beneath the manzanitas on a windswept outcrop of the park are other rare native grasses and annuals unique to the serpentine soils found in northern California. Tussock moth larvae and fungal pathogens have been attacking the few of these rare plants remaining in the wild. The Presidio manzanita, like any species with a limited geographic range and small population, is vulnerable to extinction through human error or natural disaster: one landslide, fire, or earthquake could easily eradicate the lot.
Fat pocketbook pearly mussel – Potamilus capax
Freshwater mussels act like water purifiers, filtering out suspended organic debris. The United States has the highest diversification of freshwater mussels on the planet, and many of the 300 species evolved in relation to a particular fish. The mussels’ tiny larvae attach to the fins or gills of a host fish and drop off when sufficiently grown to live in open water, thereby being distributed throughout a waterway. The fate of the mussels is tied to the fate of their host fish, and many of these native fish are now in jeopardy. Freshwater mussels make beautiful pearls of yellow, pink, silver, lavender, and metallic green. “Pearl fever” struck in 1857, and mussel beds were periodically discovered and harvested for the remainder of the 19th century. It was the demand for mother-of-pearl buttons made from mussel shells, however, that depleted most stocks. Thirty-five thousand tons of shells were harvested between 1914 and 1920 alone. In the southeast, many freshwater mussels are now extinct. Remaining populations are barely holding on because of the deleterious effects, on both the mussels and their host fish, of damming, channelization for navigation, flood control, and toxic chemicals in agricultural runoff and industrial effluent.
American burying beetle – Nicrophorus americanus
Once common throughout the eastern half of the United States, burying beetles are part of nature’s clean-up crew. The nocturnal beetles locate small carrion, such as a mouse corpse, over which pairs of males and females vie for dominance. By morning the winning couple has buried their prize. The carcass is stripped of fur or feathers and compacted into a ball covered with secretions to delay decay. The females then lay their eggs near this buried larder. When the larvae hatch three days later, the carcass provides an instant and convenient source of food for them. Both parents provide care to offspring. The larvae stroke the parents’ mandibles and in response, the parents regurgitate predigested food from the larder, much as birds do for their chicks. Habitat fragmentation, broad-spectrum pesticides, and competition from other scavengers like raccoons and skunks are all likely suspects in the burying beetle’s decline, but no one knows for certain. One theory is that the beetles evolved and declined in concert with the once abundant passenger pigeon. Because a single flock might contain 200 million birds, the death rate from old age alone could generate enough carrion to provide a niche for this and many other scavenger species. Now found in only six states—Nebraska, Rhode Island, Oklahoma, South Dakota, Kansas, and Arkansas—the beetles are being raised in captivity for re-introduction to Ohio and Massachusetts.
Oahu tree snails – Achatinella spp.
Hawaii has the dubious distinction of being home to one-third of the federally listed endangered species in the United States. Once there were over 750 different species of land snails throughout the islands. Today the entire genus of Achatinella is listed as endangered. Early Hawaiians used the shells of these colorful tree snails to make leis and other adornments. In the late 1800s there was a craze for the shells in Europe and America, with one collector accumulating 44,500 in just three years. But the most serious threat to the tree snails’ continued survival is the predatory wolf snail Euglandina rosea. E. rosea was brought to Hawaii in 1955 in an attempt to control the giant African snail (also introduced), which was becoming a lowland garden pest. However, the wolf snail vastly preferred eating the tender tree snails, and it quickly spread through the remaining forests of Hawaii, where it has caused the extinction of 52 native snail species, at last count.
Strohbeen’s parnassian– Parnassius clodius strohbeeni
Strohbeen’s parnassian butterfly was last seen in the mountains above the coastal city of Santa Cruz, California, in 1958. It is speculated that these butterflies evolved at a time when mean temperatures in the area were lower, and they retreated to higher altitudes as temperatures rose. There is mounting evidence that cities permanently affect local weather patterns by raising temperatures. Logging and development in the Coast Ranges of northern California may have contributed to pushing Strohbeen’s parnassian out of even its last foothold. Whatever the reason for its marginalization, this North American glasswing butterfly is now presumed extinct. (In 1999, when this picture was painted, the butterfly was listed by the International Union for the Conservation of Nature, or IUCN, as “near extinction.” As part of its advocacy for and monitoring of global biodiversity, the IUCN compiles the Red Lists of Threatened Species used by conservation groups worldwide.)
Delta green ground beetle – Elaphrus viridis
The delta green ground beetle is a tiny inhabitant of California’s vernal pools. Vernal pools are shallow freshwater ponds that fill up during the winter rains and dry out gradually through the summer. Animals such as the tiger salamander, fairy shrimp, and ground beetle have evolved life cycles perfectly suited to this changing habitat. Many of the wildflowers found around the edges of drying vernal pools actually begin their lives as aquatic plants. Found only in the grassland of the Central Valley and the southern coastal region, the pools are home to some 40 unique endemic plants. Many areas containing vernal pools have been developed or have disappeared beneath the plow. Delta green ground beetles live now only in the Jepson Prairie Reserve and on a patchwork of adjacent private land near Vacaville, CA.