2. Why Do We Care About Urbanization?
• Globally
– Roughly 39-50% of land has been converted to
human uses
– The world’s urban population was 50% in 2000 and
is expected to reach 70% by 2050
– About 17% of land is protected
• In the U.S.
– Urban land increased by 1.1 million acres per year
between 1960-1980
– By 1989, 74% of the population lived in urban areas
• In Central Puget Sound
– The population has increased by 2 million people
since 1960
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3. Urban Sprawl
A form of urbanization distinguished by
Large areas of single-use development
(residential)
• Heavy reliance on automobiles
• Minimal public open space
• Leapfrog patterns
• Commercial strips
• Low density
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5. Persistence
of
Change
Similarity of Matrix to Natural Habitat
High Low
Low
High
Agriculture
Timber
Harvest
Urbanization
Effect of
Fragmentation
Contrasting Various Land Covers
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7. urban suburban exurban wildland
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The Urban Gradient
• Shift in
Imperviousness (paved)
Forest cover
Exotic species
Biodiversity
8. Settlement has varying effects on
wildlife species
• Reduced predation
• Reduced climatic
extremes
• Available water
• Supplemental food
• New nest sites
• Increased edge and
vegetative diversity
• Increased predation
• Reduction in nest sites
• Reduced food
• New disturbances
• Increased edge and
vegetative diversity
Some benefits: Some costs:
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9. Effects of Urbanization
• Convenient to think of
wildlife in three categories
– urban avoiders
– urban adapters
– urban exploiters
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10. Effects of Urbanization
• Declining and threatened/endangered species are usually
native urban avoiders suffering from
• Habitat loss, fragmentation
• Interaction with non-native species (predation and
competition)
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12. Settlement Benefits Some Wildlife
• Reduced predation
• Available water
• Supplemental food
• New nest sites
• Increased edge and
vegetative diversity
12
13. Effects of Urbanization
• Urban adapters can benefit
from urbanization if sufficient
native habitat remains
• Able to live in small patches
and/or
• Adapt to altered environment
13
14. Effects of Urbanization
• Urban exploiters increase with
urbanization and exploit new &
altered environment
• Both native and non-native
• Serve to homogenize species in
cities
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15. Loss of native specialists (avoiders) and
gains in generalist and synanthropic species
(adapters and exploiters) explain diversity
patterns
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Patterns
16. Some Birds Found Consistently In Cities
Around The World
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Global
homogenization
of some wildlife
communities a
concern.
17. Wildlife Communities Change Along
The Urban To Wildland Gradient
Loss and fragmentation of original habitat
Shift in vegetative structure and composition of habitat
fragments and the urban matrix
Alteration of population dynamics processes (reproduction,
survivorship, dispersal)
Species losses and gains
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18. Effects of Urbanization
• Other organisms in cities:
• More non-native plants, insects with increased
urbanization
• Greater plant diversity in larger habitat patches
• Small mammal diversity and density decrease
with urbanization
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19. Primary Problems For Urban
Wildlife
• Loss of habitat (amount
and connectivity)
• Simplification of habitat
(quality, exotics)
• Invasion by exotic species
(competition, disease)
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20. Primary Problems for Urban
Wildlife
• Predation by domestic animals
(cats, dogs)
• Predation by wild animals
(corvids, squirrels, rats)
• Increase in accidents (cars,
windows, power lines, fences)
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21. Raptors as City Dwellers
• Some raptor species can thrive in
urban areas
• Able to use artificial nest
platforms
• Find abundant prey
• Relatively free from persecution
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22. Suburban v Rural Eastern Screech Owls in
Texas:
• Nested earlier (urban heat
island)
• Larger clutches (more food)
• More and larger fledglings
(food and low predation)
• More recruits into population
• Higher fitness
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23. Controlling Sprawl
• Sprawl is a strong driver of the urban footprint
• Results in loss, fragmentation, and degradation of habitat
• Increases energy use
• Increases pollution from commuting
• Growth Management is needed to control it
• Limits most future growth inside Urban Growth Boundary
• May just displace the problem if regional planning is not
incorporated (leapfrogging)
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25. Wildlife Conservation in Urban Areas
Preserve large areas of habitat
• The area, numbers, and connectivity of reserves should be
maximized
• Buffers should be maintained around reserves
• The amount of edge and degree of fragmentation within
reserves should be minimized
• The scale of reserve planning should be expanded beyond
the local area to include entire watersheds and bioregions
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26. Wildlife Conservation in Urban
Areas
Enhance habitat locally
• Retain as much natural habitat as possible (especially new
housing)
• Plant native plants, fruit-producing exotics
• Retain understory and snags
• Minimize lawn cover
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27. Wildlife Conservation in Urban
Areas
Provide essential resources:
• Places to breed (nest boxes, platforms, trees)
• Feeding stations (squirrels, birds)
• Water
• Cover (vegetation)
Provide protection from domestic predators
• Control dog and cat behavior
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28. Wildlife Conservation in Urban
Areas
Reduce accidental mortality:
• Birds crashing into windows
• 3.5 million birds/yr
• Birds hitting buildings, towers, etc.
• 1.5 million birds/yr
• Avoid planting fruit-bearing plants/trees next to highways
• Clean bird feeders frequently (Salmonella)
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29. Wildlife Conservation in Urban
Areas
Support urban planning initiatives and education
• Clustered development
• Growth management
• Open space preservation
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