Birds without humans

DMZ, Chernobyl, Guam, Yellowstone and Vertac

Hooded Mergansers in breeding plumage are the glamour birds of once-polluted Vertac in Jacksonville.
Hooded Mergansers in breeding plumage are the glamour birds of once-polluted Vertac in Jacksonville.

Select the most accurate statement:

A. Birds can survive without humans,

B. Humans can survive without birds.

C. Birds cannot survive without humans.

D. Humans cannot survive without birds.

Before you decide on an answer, consider the history of five areas on the globe, all natural laboratories that suggest answers: The Demilitarized Zone in Korea, Chernobyl, Guam, Yellowstone National Park, and Vertac, the once polluted Superfund plant site in Jacksonville, Arkansas, that manufactured Agent Orange.

Also consider trophic cascade, a biological phenomenon that recognizes the way creatures at the top of a food chain impact the species below it, at work in these far-flung natural laboratories.

The Vertac plant was an ecological wasteland in 1969. It has been reshaped into areas for civic uses and 93 acres of refreshed land for wildlife with a viable ecosystem. Before looking at this site, however, here are four other locations where trophic cascade is at work with humans being at the top of the food chain.

Demilitarized Zone

The DMZ is a three-mile sliver of land between North Korea and South Korea that stretches across the peninsula at the 38th parallel. Since 1953, by international agreement it is not regularly inhabited by humans. Even if it was, the area is filled with dangerous unmarked landmines. When the treaty which ended the Korean War was signed, it established the DMZ, evacuated the inhabitants and prevented resettlement.

Afterward, the DMZ was filled with a great number of birds. Most were native to the area but had earlier seen their numbers dwindle because of hunting, the ravages of war, and pollution. Today, endangered birds and animals flourish in the DMZ. It is likely the finest bird sanctuary on the planet where humans are not allowed.

Chernobyl

Ukraine's Chernobyl is the site of the worst nuclear accident in human history in 1986. After an explosion and meltdown, the town and countryside within a 19-mile radius was evacuated. The government announced, "Comrades must leave now, in three days you will be allowed to return." Three days has now become almost three decades. The area was quarantined.

As in the DMZ, birds began to replace people in abundance. Biologists were taken aback by the increase in wildlife in the area surrounding Chernobyl, particularly in the first 10 years after the accident. Since that time, low-level radiation has taken a toll on birds. Birth defects, sterility and the development of cataracts on the eyes of birds have thinned their numbers, although they are still well above pre-explosion populations. However, the birds are not healthy. The impact of the radiation has not been evenly distributed. Birds higher on the food chain have been impacted profoundly. Crows, blackbirds and starlings seem to be more resistant to radiation's ill effects than colorful birds with yellow and red feathers.

Guam

The birds on the subtropical Pacific island of Guam were abundant before World War II when the island became the site of an airport and shipping station for U.S. forces. Construction of the airport was a shock to the island's ecosystem. After the war when the airport became a hub for commercial shipping, brown tree snakes that were stowaways in crates were introduced to Guam. The population of the snakes began to grow. At first they provided a new food source for the island's birds of prey, but the hawks could not keep up with the birth rate of the snakes. Soon the snakes were crawling into the nests of the hawks and eating their eggs and their young, so much so that snakes soon had no native predator and their population increased even more. Some endemic species on the island became extinct. The snakes, as well as rats and mice that came to Guam with the snakes, killed the young of songbirds and ground-nesting birds. With the disappearance of birds, the insect population on the island exploded, particularly a species of large spider that builds its webs everywhere, making Guam a creepy and uncomfortable place for humans to live.

Yellowstone

Yellowstone National Park has been a place of restricted human activity for decades. Eagles, ospreys, magpies, Steller's jays and other birds are there in relative abundance. A few years ago, however, park rangers began to notice a decline in migratory songbirds nesting in Yellowstone. This has been linked, interestingly, to the shooting and removal of wolves from the park by humans in response to complaints from surrounding ranchers.

Vertac

The Vertac plant site in Jacksonville was where Agent Orange, a powerful defoliant used in the Vietnam War, was produced in the 1960s. The manufacturing of this product was so toxic to the environment around the plant that people living nearby were blaming the site for cancer in humans. Fish in the Bayou Meto watershed were dying, and eating the fish was deemed harmful to children and pregnant women. Though there is scant evidence of the avian and botanical features of the landscape before the plant opened, it is obvious that by 1970 the immediate area had become a wasteland. Without grain-bearing grasses and flowering plants to attract insects, and the loss of suitable trees for nesting sites, the birds lost habitat and abandoned the area for greener pastures.

After millions of Superfund dollars spent in cleanup efforts, the 200 acres around Vertac are slowly putting their natural ecosystem in order. Parts of the reclaimed property have become suitable for safe land use purposes and have been given to the city of Jacksonville for use as a firefighters' training area, a shooting range and a recycling center. The 93-acre core manufacturing space for Agent Orange has been fenced away from the public, and runoff-water and soil-treatment systems have been implemented there for two generations.

Terracon, an environmental engineering firm, is in charge of monitoring the site and protecting the adjacent areas from further ecological decay. Coyotes have replaced humans at the top of the food chain inside the fences at Vertac. Recently a group of avid bird-watchers was allowed inside those fences. The birders found 43 species of birds on their four-hour visit. There were many more birds and animals at the waste site than the birders were accustomed to seeing in such a small area. The symbiotic relationship of bird populations to human activity seen in Korea, Chernobyl and Yellowstone is being played out at Vertac on smaller scale.

People shape the landscape for human needs without regard for avian survival. People build roads and travel down them at a high rate of speed, causing millions of bird deaths by collision each year. They build houses with many glass windows that kill birds when they fly into them. They plant exotic grasses on their lawns that provide no nutrition for birds. Humans protect domestic and feral cats and dogs that ravage nesting wild birds. Little boys test their BB gun skills on songbirds. Such things do not happen at Vertac. The human activity conducted by Terracon at the site is limited to cleaning the water, planting nutritious grasses and trees, and preventing the shooting of coyotes or the poaching of the ducks, turkey and deer.

These five locations are not the only places where trophic cascade is at work. It is also seen in Appalachia, Illinois, Arizona, Indiana and Kentucky, where the spoil banks of strip mining left vast tracts of land uninhabited or uninhabitable; on the politically divided island of Cyprus with a DMZ of its own; in the Galapagos Islands; and Catalina Island off the California coast. In all of these places where humans are not the dominant species, the impact upon the birds is clear.

Jerry Butler publishes regularly about birds and their relationship to people. Email him at jerrysharon.butler@gmail.com.

Editorial on 10/19/2014

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