Download The Main Causes of Endangerment and Extinction in the United States

The Nature Conservancy
Photo: Thomas G. Barnes
The Main Causes of Endangerment and
Extinction in the United States
Thanks to the other speakers:
Dan Evans
Dale Goble, Curt Flather, Camille Parmesan, Mark Schwartz, Maile Neel, Haldre Rogers,
Ariana Sutton-Grier, Sylvia Fallon, Mike Scott
Thanks to the ESA Public Affairs Office:
Terence Houston, Nadine Lymn, and Sharon Collinge
Setting the Ecological Stage
To understand why species become endangered or go extinct, we
need to consider the ecological threats they face
DM Evans
People – Our activities are endangering other species
DM Evans
Which human activities are pushing species to the brink?
Habitat
destruction
and
degradation
Introduction
of exotic
invasive
species
Pollution
Overexploitation
Which human activities are pushing species to the brink?
Habitat
destruction
and
degradation
Introduction
of exotic
invasive
species
Pollution
Overexploitation
Which human activities are pushing species to the brink?
Caveats:
• Different types of species are vulnerable to different ecological threats
• Practically all species on the endangered species list face
multiple threats
Habitat
destruction
and
degradation
Introduction
of exotic
invasive
species
Pollution
Overexploitation
When evaluating candidates for the endangered species list
The government must consider:
• “destruction, modification, or curtailment of habitat . . .
Endangered Species Act Sect. 4(a)(1)
Habitat
destruction
and
degradation
Introduction
of exotic
invasive
species
Pollution
Overexploitation
When evaluating candidates for the endangered species list
The government must consider:
• “destruction, modification, or curtailment of habitat . . .
• . . . disease or predation . . .
Habitat
destruction
and
degradation
Introduction
of exotic
invasive
species
Endangered Species Act Sect. 4(a)(1)
Pollution
Overexploitation
When evaluating candidates for the endangered species list
The government must consider:
• “destruction, modification, or curtailment of habitat . . .
• . . . disease or predation . . .
Endangered Species Act Sect. 4(a)(1)
• . . . overutilization for commercial . . . [or other] purposes . . .”
Habitat
destruction
and
degradation
Introduction
of exotic
invasive
species
Pollution
Overexploitation
Ranking the threats to endangered species
These threats have varied in their degree of threat, now and historically
#1
Habitat
destruction
and
degradation
Introduction
of exotic
invasive
species
Pollution
Overexploitation
DM Evans
Ranking the threats to endangered species
#1
Habitat
destruction
and
degradation
agriculture
Ranking the threats to endangered species
#1
Habitat
destruction
and
degradation
Habitat fragmentation
Ranking the threats to endangered species
#2
Introduction
of exotic
invasive
species
Ranking the threats to endangered species
#2
Introduction
of exotic
invasive
species
Ranking the threats to endangered species
#2
Introduction
of exotic
invasive
species
Ranking the threats to endangered species
#3
Pollution
Only in the last 100 years . . .
US Population
since 1900
350,000,000
300,000,000
250,000,000
200,000,000
150,000,000
100,000,000
50,000,000
0
1900
20
US Gross Domestic Product
since 1900
(trillions of current $)
15
10
5
1950
2000
0
1900
Source: US Census Bureau
Habitat
destruction
and
degradation
Introduction
of exotic
invasive
species
Pollution
1950
2000
Source: US Bureau of Economic Analysis
In the 18th and 19th centuries overexploitation was #1
Overexploitation
In the 18th and 19th centuries overexploitation was #1
Future challenges for the Endangered Species Act
Conclusion
• In 1973, the Endangered Species Act was designed largely to stop
that kind of overexploitation.
• But the other threats I’ve discussed today, coupled with climate
change, present new challenges for the 21st century.