The study, published in the September issue of Ecology and Society, examined a combination of 15 social and ecological variables -- from tourism and per capita gross domestic product to water stress and political stability. Then researchers analyzed their correlations with invasive and endangered birds and mammals, which are two indicators of what conservationist Aldo Leopold termed “land sickness,” the study said.
Human life expectancy, which is rarely included among indexes that examine human impacts on the environment, surfaced as the key predictor of global invasions and extinctions.
“It’s not a random pattern,” said lead author Aaron Lotz, a postdoctoral scholar in the Department of Wildlife, Fish and Conservation Biology when the study was conducted. “Out of all this data, that one factor -- human life expectancy -- was the determining factor for endangered and invasive birds and mammals.”
The study analyzed data from 100 countries, which included roughly 87 percent of the world’s population, 43 percent of global GDP per capita, and covered 74 percent of the Earth’s total land area. Additional factors considered were agricultural intensity, rainfall, pesticide regulation, energy efficiency, wilderness protection, latitude, export-import ratio, undernourishment, adult literacy, female participation in government, and total population.
The findings include:
- New Zealand, the United States and the Philippines had among the highest percentages of endangered and invasive birds.
- New Zealand had the highest percentage of all endangered and invasive species combined, largely due to its lack of native terrestrial mammals. The study said that in the past 700 to 800 years since the country was colonized, it has experienced massive invasion by nonindigenous species, resulting in catastrophic biodiversity loss.
- African countries had the lowest percentage of invasive and endangered birds and mammals. These countries have had very little international trade, which limits opportunities for biological invasion.
- As GDP per capita -- a standard measure of affluence -- increased in a country, so did the percentage of invasive birds and mammals.
- As total biodiversity and total land area increased in a country, so did the percentage of endangered birds. (Biodiversity in this context is not a measure of health but refers to the number of species in an area.)
“Some studies have this view that there’s wildlife and then there’s us,” said Lotz. “But we’re part of the ecosystem. We need to start relating humans to the environment in our research and not leave them out of the equation. We need to realize we have a direct link to nature.”
As for Mill Valley
From red-tailed hawks and mountain lions on the slopes of Mount Tam to oysters and harbor seals in the bays and on the coast, a diversity of wildlife inhabits Marin County. The fish, birds, mammals, reptiles, amphibians, and invertebrates that live here depend on healthy watersheds to survive.The Marin County Watershed Program continues to preserve wildlife habitat, as well as educate the community on the array of species that call areas like the Southern Coastal Creeks watershed home.
The watershed reports that more than 150 species of birds live and breed in Marin County, including a number of rare and threatened species, as well as, mountain lions, black-tailed deer, coyotes, and other mammals that must be able to move to survive.
Marin’s Southern Coastal watersheds include Webb Creek, Lone Tree Creek, Cold Stream, Redwood Creek, Alder Creek, Rodeo Lagoon, and Tennessee Valley; where identified special-status species include Coho salmon, steelhead trout, California red-legged frog, monarch butterflies, northwestern pond turtle, northern spotted owl, and many more.
The Southern Marin Watershed Program is a collaborative effort of the City of Mill Valley, the County of Marin, and Flood Control Zones 3 and 4. The purpose of the Watershed Program is to provide a framework to integrate flood protection and environmental restoration with public and private partners to protect and enhance Marin County’s watersheds and to identify solutions that will enhance and protect the diverse habitat of the lands that drain into Richardson Bay.
The WMP will identify opportunities that provide the following benefits:
- Develop cost effective solutions to help reduce flooding
- Protect, enhance, and restore sensitive creek and wetland habitat and water quality
- Identify multi-benefit projects that will improve the ability to compete for state and federal funding
- Identify the impacts of sea level rise and develop project concepts that could be adapted to rising tides
- Evaluate the beneficial re-use of dredged sediment from Coyote Creek and other sediment removal projects for wetland restoration, levee maintenance, and shoreline protection
- Improve efficiency of existing flood maintenance operations