Transcript Conservation biology - Donald Edward Winslow

Conservation Biology
Donald Winslow, 28 January 2011
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Defining conservation biology
Valuation of biodiversity
Threats to biodiversity
Solutions for conservation challenges
Sustainability
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Living in ways that do not degrade
resources on which future generations
depend, allowing civilization to persist.
Defining Conservation Biology
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The natural world
World ecosystems
Biodiversity conservation
History of conservation biology
Valuation of Biodiversity
• Extrinsic values
– Economic uses of species
– Medical uses of species
– Genetic resources
– Ecosystem services
• Intrinsic value
Threats to biodiversity
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Human population growth
Human industry and resource use
Extinction of species
Loss of genetic diversity
Habitat change
Overexploitation
Invasive species & disease
Climate change
Habitat change
• Habitat destruction
• Habitat degradation
• Fragmentation
Habitat destruction
• Primary cause of biodiversity loss
• 80+% of threatened species affected by
habitat destruction or degradation
• A decrease in habitat availability
decreases the number of breeding
territories and thus population productivity.
Destruction vs. degradation
• Destruction: Changed to such an extent
that one or more ecological populations
can no longer use the habitat.
• Degradation: Habitat still used, but
individuals have lower fitness and
populations reduced viability.
Habitat fragmentation—
loss of contiguity as well as area.
Neotropical Migrant Birds
Winter in tropics in
Central and South
America.
Breed in temperate
North America during
the spring & summer.
Long-term continental declines have been
observed in a number of species.
Wood Thrush (Hylocichla mustelina) incubating
Hatching Wood Thrush nest next to regeneration opening
Breeding Bird Survey
http://www.mbr-pwrc.usgs.gov/bbs
Neotropical migrants are
dependent on:
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Breeding habitat
Migratory stopover sites
Winter habitat
Therefore, long-distant migrants link the
ecosystems of the hemisphere, and
• They are vulnerable to threats in each of
these habitats.
Threats on breeding grounds:
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Habitat destruction.
Habitat degradation.
Habitat fragmentation.
Brood parasitism by Brown-headed
Cowbirds (Molothrus ater).
• Nest predation by various nest predators.
• Agricultural pesticides reduce food
availability and poison birds.
Human land-use patterns affect the
abundance, distribution, & activity of
cowbirds & nest predators
• Cowbirds feed in pastures, agricultural
fields and lawns.
• Cowbirds and many nest predators
(e.g. Blue Jays, rat snakes, and raccoons)
use forest edges.
Brown-headed Cowbirds
(Molothrus ater)
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Do not build their own nests.
Lay their eggs in the nests of other birds.
Often remove a host egg from the nest.
The host parents raise the cowbird young.
Cowbird nestlings out-compete host young
and sometimes push them from the nest.
Brown-headed Cowbirds (Molothrus ater)
Nests parasitized by cowbirds
Nest predators in
Midwestern forests include:
• Blue Jays and crows.
• Snakes, such as the black rat snake.
• Large mammals, such as racoons and
skunks.
• Small mammals, such as squirrels and
mice.
• Many other birds and mammals may harm
eggs and nestlings if given a chance.
Rat snake (Elaphe obsoleta)
preying on Wood Thrush
(Hylocichla mustelina) nest.
Edge Effects on
Cowbird Parasitism
An “edge” is the border or transition
between two habitat types.
• Agricultural edges
• Urban or suburban edges
• Roads
• Internal edges from clearcuts or maintained
wildlife openings
Timber is extracted from Indiana state forests
using individual and group selection techniques
• Individual selection—Individual trees are
removed from within a harvest tract.
• Group selection—Small openings are
created by removing groups of trees.
• Site preparation entails the construction
and maintenance of roads, skid trails, and
log landings.
• These methods generate high edge
density.
Regeneration opening, Compartment 1, Tract 16
Acadian Flycatcher
(Empidonax virescens)
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Breeds in eastern United States.
Winters in Central and South America.
Nests in mature forest, May-August.
Nest suspended from fork in branch, typically 37 m high.
• Clutch size usually 3.
• Female incubates.
• Both parents feed young.
Checking the contents of a Red-eyed Vireo nest.
Objective—Experimentally evaluate the effects
of logging in Yellowwood State Forest on nest
survival and cowbird parasitism level.
Hypothesis—Timber extraction decreases nest
survival (by increasing predation) and increases
parasitism.
Prediction—Nest survival will be lower and
parasitism higher after logging than before,
relative to values measured in unlogged sites.
Study Sites
• Nests in eight tracts in Yellowwood State
Forest were monitored in 1995 & 1996.
(Three were also monitored in 1994.)
• Four sites were logged between 1995 &
1996.
• The other four sites were close to rotation
age but remained unlogged during 1996.
Overall Success Rate of
Acadian Flycatcher nests in Yellowwood State Forest
before (1995) and after (1996) treatment sites were logged.
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Control
Treatment
0.8
Treatment:Control 1.22
Treatment:Control 0.563
OSR
0.6
0.4
0.2
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1995
1996
Year
Ratio of 1996 OSR ratio to 1995 OSR ratio: 0.460, p < 0.025 (one-tailed)
Proportion of Acadian Flycatcher nests parasitized
before (1995) and after (1996) treatment sites were logged.
0.25
Proportion parasitized
Control
Treatment
0.2
0.15
0.1
0.05
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1995
1996
Year
Interaction effect: G = 3.49, df = 1, p = 0.031, (one-tailed)
Possible interpretations
• If factors responsible for between-year
variation operate similarly in both sets of
sites, the observed interactions between
year and treatment may indicate logging
decreases breeding success.
• Alternatively, site-specific processes at
control tracts may have caused higher
success in 1996.
Lessons from Indiana
• Where avian conservation is a priority in
eastern deciduous forests, timber
extraction should be limited until effects on
nesting success are understood.
• Special attention should be given to
monitoring breeding success of bird
species that preferentially select edge
habitats.
Solutions to
conservation challenges
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Population level
Species level—in situ and ex situ
Ecosystem level—protection & restoration
Landscape level
Regional level
Global level
Conserving evolutionary processes
Sustainability
Sustainable practices are practices that can
continue indefinitely—without depleting or
degrading resources needed to continue.
Agriculture
Industry
Economy
Human relations