published in the Pacifica Tribune July 10,2019
Celebrating America’s Environmental Stewardship
I resent the one-sided mis-characterization of humanity as “destroyers of our environment”. Humans certainly had negative impacts on most ecosystems. However, in contrast to a recent United Nations report insinuating we are threatening one million species with extinction, humans have been working hard to restore nature and prevent further extinctions. Most endangered species are still staggering from disruptions initiated centuries ago. But now humans are correcting past mistakes.
Islands have been extinction hotspots. Sixty-one percent of all known extinctions have occurred on islands and 37% of today’s critically endangered species are found only on islands. The main driver of island extinctions has been purposeful or unintentional introductions of alien species. Introduced species are implicated in 81% of all island extinctions. With no natural predators, Island species did not evolve needed behaviors to avoid introduced rats, cats and stoats. Researchers now suggest eradication of rats and other introduced mammals could prevent the extinction of up to 75% of threatened island birds, reptiles and mammals.
Similarly, past introductions of disease decimated island species whose immune systems were ill-prepared to combat alien pathogens. For example, after sailors inadvertently introduced mosquitos into Hawaii in the early 1800s, mosquitos began transmitting avian malaria. By the late 1800s Hawaii’s lowland birds were noticeably disappearing, even in undisturbed habitat. Mosquitos were restricted to warmer lowlands, so cooler high elevations served as a refuge. But high elevation birds regularly migrate to the relative safety of lowland valleys during winter storms, so are still threatened by malaria. Due to landscape changes, introduced predators and introduced diseases, Hawaii became known as the extinction capital of the world. Unfortunately eradicating introduced diseases will be extremely difficult.
|Extinct Hawaiian Akialoa lanaiensis|
In 1750 Russian fur farmers began introducing red and arctic foxes to the Aleutian Islands. Breeding birds that once thrived in predator-free environments were deemed fox food. By 1811 native Aleuts complained foxes were reducing once abundant seabirds but populations continued to plummet. The Aleutian goose was soon considered extinct until a few pairs were found on 3 fox-free islands. Humans embarked on programs to eradicate introduced foxes allowing seabirds and geese to recover. The Aleutian goose recovery has been so rapid, that along the coast of northern California where the geese winter, they are now considered a pest in local parks.
Lost habitat has caused many extinctions, especially species dependent on rapidly disappearing wetlands. For centuries wetlands were being drained and converted to croplands and pastures. However, in the United States that trend is being reversed. Due to more efficient farming methods, the extent of land covered by crops decreased 18% between 1938 and 1992, allowing most of that land to return to more natural habitat. Due to improved wildlife management and incentives to conserve wetlands, wetland-dependent birds have increased by over 30% since 1968. Unfortunately, the incentives to protect wetlands have been counteracted by misguided government subsidies for biofuels in the name of fighting climate change. As a result, some farmers have been enticed to drain their wetlands to grow corn.
The probability of extinction by chance is greatly enhanced when a species’ range is extremely small, and their original abundance is low. Minor habitat disturbances can then cause extinctions. For example, most extinct plant species in California were found in only one or two counties, and due to low abundance were known only from one or two collections.
Nonetheless people are still striving to restore wetlands. We preserve habitat by establishing land trusts. My research prompted restoration of a Sierra Nevada watershed that was initially degraded over 100 years ago. Meadows then stayed wetter during California’s 3-year drought than had been the case before the drought and before restoration. Furthermore, bird populations significantly increased. Colleagues are now restoring other meadows as are several other non-profit organizations.
The United Nations’ report hyping one million extinctions in the near future should be regarded with extreme suspicion. It engages in fearmongering that only evokes a sense of helplessness. It repeatedly argues their environmental goals for 2030 and beyond “may only be achieved through transformative changes across economic, social, political and technological factors.” Their proposed remedy smells of a hidden political agenda. It ignores the tremendous strides humans have taken towards being better environmental stewards.
Our situation is not hopeless. Simply funding the eradication of invasive species on islands would save a significant number of threatened species. America’s regulations have promoted the recovery of several endangered species now listed as species of “least concern”: bald eagles, humpback whales, brown pelicans and many more. Improved agricultural practices and our efficient economy have allowed more land to convert from cropland back to natural habitat despite feeding a growing human population. Learning from past mistakes, we are now on a trajectory to create win-win situations for both humans and the environment.
Jim Steele is retired director of the Sierra Nevada Field Campus, SFSU