Download Urban Areas

Urbanization and Wildlife
Why do we care about urbanization?
Urbanization
• Rapid urban growth over the past ~50 years
• By 2030, approximately 2/3 of humanity will be urban
An Increasing Urban Population
Interesting website: http://www.worldometers.info/
Why Are Urban Populations
Increasing?
• The world’s population is increasing
• People are migrating to cities
• Developed nations have higher percentage
of urban residents than less developed
Why are people migrating to cities?
Urbanization: A Rising Tide
(WRI 1996)
Becoming More
Urban
Sprawling From
Urban Centers
Typical location of cities exaggerates impacts, why?:
Typical location of cities exaggerates impacts:
coasts, river mouths, lakes, fertile inland areas
The World’s Urban Centers
Tokyo > 34 million (greater metro); several others > 20 million (incl. NYC)
Puget Trough Ecoregion (2)
8% of the land area of the state - contains over 70% of
Washington's human population.
Source: Seattle Audubon Society’s BirdWeb
Urbanization isn’t just high rises
and city centers…
Houses/markets outside Nairobi, Kenya
Urban Sprawl
A form of urbanization distinguished by
– Large areas of single-use development (residential)
Heavy reliance on automobiles
– Minimal public open space
– Commercial strips
– Low density
Urban Sprawl: An Example
4% population increase drove 49% increase in developed land
Urban Areas Have Large
Ecological Footprints
• Ecological Footprint: Amount of land and water area
a human population requires to produce the resources
it consumes and to absorb its wastes
• A larger, more intensively used area is needed to
support urban areas
Urban Areas Have Large
Ecological Footprints
Urban footprints can be highly dispersed:
Chicago’s famous pizza
• Cheese from Wisconsin
• Flour from Kansas
• Oven from Japan or China
Urban Areas Have Large
Ecological Footprints
What is this graph telling us?
Urban Areas Have Large
Ecological Footprints
What is this graph telling us?
Generating waste quicker than
It can be turned back into
Something useful.
Using more resources than are
renewable
23% too high
Urban Areas Have Large
Ecological Footprints
How big is your footprint?
http://www.footprintnetwork.org
http://www.myfootprint.org/
23% too high
The Urban Gradient
urban
suburban
exurban
Shift in:
•
•
•
•
Imperviousness (paved)
Forest cover
Exotic species
Biodiversity
wildland
Species Biodiversity
Why is the number of species detected
lower in fully forested areas?
Marzluff 2005
The Urban Gradient and Temperature
Urban heat island
Why is it hotter in cities?
Urban Areas: Varying Effects on Wildlife
Some benefits:
• Reduced predation
• Reduced climatic
extremes
• Available water
• Supplemental food
• New nest sites,
living areas
• Increased edge
Some costs:
• Increased predation
• Reduction in nest
sites (& other living
areas)
• Reduced food
• New disturbances
• Increased edge
Vegetation amount and arrangement
Vegetation structure and composition
Food supply
Photo: Joan Gellatly
Nesting opportunities
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
Predators, competitors and disease!
Feral Cats
• ~77 million pet cats in US
• Also millions of feral cats
• Each year
– Cats estimated to kill
hundreds of millions of
birds and small mammals*
• Cats are a threat to urban
biodiversity
*American Bird Conservancy
Controlling Urban Sprawl
• Sprawl is a strong driver of the urban footprint
– habitat loss/degradation, fragmentation
– increases energy use
– increases pollution (e.g. 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)
Growth Management Act - 1990
King County Comprehensive Plan
Subdivision Planning
Which plan is better
for maintaining
habitat?
standard
clustered
Gillham (2002)
Subdivision Planning
Clustered subdivision:
• Smaller lots
• Higher density of homes
• More open space
standard
clustered
Gillham (2002)
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
 Large scale (consider bioregions)
Marzluff and Ewing (2001)
Wildlife Conservation in Urban Areas
Enhance habitat locally (backyard habitat)
• Retain as much natural habitat as possible
(especially new housing)
• Plant native plants
• Retain understory and snags
• Minimize lawn cover
Wildlife Conservation in Urban Areas
Backyard Habitat
Provide essential resources:
•
•
•
•
Food (feeders, vegetation)
Water
Cover/shelter (vegetation)
Place to raise young (nest boxes, etc.)
Provide protection from domestic predators
• Control dog and cat behavior
Wildlife Conservation in Urban Areas
Reduce accidental mortality:
•
Roadkill
1 million animals killed/day by cars; many in cities
•
Birds crashing into windows/hitting buildings, etc.
5+ million birds/yr
•
Disease from bird feeders (Salmonella)
Wildlife Conservation in Urban Areas
Support urban planning initiatives
and education
• Clustered development
• Growth management
• Open space preservation
Community gardens
• Local food
• Shelter for wildlife
• Organic (no chemicals)
• Preserve open spaces
• More permeable surfaces
• Ecological and Environmental Ethic (stewardship)
Community gardens
PLUS: Many socio-economic benefits!
Community Garden: Bronx Green-Up
Transforms vacant, abandoned lots to community gardens
http://www.nybg.org/green_up/comm_gard.php
Community Garden: UW Farm
Green Roofs
Rockefeller Center
• Provide wildlife habitat
• Catch rainfall
• Help lower urban temperatures
• Decrease stress for humans
http://www.greenroofs.org/
Chicago City Hall