The Footprint of Urbanization
Changes in Land-use and Land- cover Global changes: (Meyer and Turner 1992) –Cropland % –Irrigated Cropland +2400% –Closed Forest -15.1% –Forest and woodland-14.9% –Grassland/pasture-1% –Lands drained1.6 x 10 6 km 2 –Urban settlement2.5 x 10 6 km 2 –Rural settlement2.1 x 10 6 km 2 (Lambin et al. 2001)
Settlement Affects Native Habitat Habitat Loss Reduced connection among remaining patches Perforation of large patches Introduction of exotics Degradation of remaining habitat
Settlement Benefits Some Wildlife Reduced predation Reduced climatic extremes Available water Supplemental food New nest sites Increased edge and vegetative diversity
What Can We Learn From A Decade of Work in Seattle? Insights from: Heather Cornell, Roarke Donnelly, Kara Whittaker, Cara Ianni, John Withey, Tina Blewett, Jack DeLap, Laura Farwell, Dave Oleyar, Jorge Tomasevic, Thomas Unfried, Stan Rullman
Change is Rapid and Dramatic
Communities are of Similar Structure, But Different Composition
As Urbanization Increases and Forest is Reduced, Bird Diversity Increases, then Decreases (Marzluff 2005)
Extinction (local extirpation) and colonization determine the pattern of diversity along a gradient of urbanization
Extinction and Colonization
Relative Abundance (birds counted within 50 m during 10 mins)
What are the Mechanisms? Reproduction Dispersal Survival Population Size
Study Area From 1999 to 2009, we count, map, band, and resight birds within forest patches from 3 landscape types: Forest reserves (5) Developed Subdivisions (9) Changing landscapes (13)
Reserve sites are primarily forested. Changing sites are undergoing residential development during the study Developed sites are older residential areas built prior to the onset of study.
A Childhood Question m Pacific Wren
Song Sparrow m Adapters Wait Out Change
Avoiders Move During Development
Monitoring Productivity and Survivorship Productivity---Territory success and fledgling estimates via spot mapping and nest monitoring. Color-banded individuals of 7 species: # Colorbanded Individuals # Territories/Nests Monitored American Robin Bewick’s Wren Dark-eyed Junco Song Sparrow Spotted Towhee Swainson’s Thrush Winter Wren195552
A Diversity of Nest Predators
Estimating survival in different landscapes: Yearly encounter histories based on recapture and resighting of colorbanded individuals. Used Cormack-Jolly-Seber model in Program MARK and RMARK. Best model based on AICc included: species, landscape, and age (juvenile and adult). Survival (apparent) differed by species and also by landscape for some species Photo by T. Unfried
Landscape Specific Survival
Densities Much Lower than Non-Settled Areas Zarnowitz and Manuwal (1985) This study – entire Site This study – Forest only (Blewett and Marzluff 2005 Condor 107: )
Population Size is a Critical Determinant of Whether Species Adapt or go Extinct in Urban Environments (Marzluff 2012)
Expected Changes (Hepinstall et al. 2008)
Spatial Changes
Winners
And Losers Pacific-slope Flycatcher
Approaching a Tipping Point? (Marzluff 2005 Urban Ecosystems 8: ) Projected Forest Decline
Some Winners May Accentuate Losses Farwell and Marzluff 2013, Biol. Conservation
What are the Mechanisms? Reproduction √ Dispersal Survival √ √ Population Size √ √ √ Future Directions –Primary Productivity –Facilitation –Competition –Coevolution with People
Wider View (Canada) (Calvert et al Avian Cons. And Ecol.)
A Bird Friendly Morality 1.Thou shall not covet thy neighbor’s lawn. 2.Thou shall not allow thy cat to roam. 3.Thou shall make thy windows visible. 4.Thou shall not light the night sky. 5.Thou shall provide food and nest boxes. 6.Thou shall not kill native predators. 7.Thou shall abhor uniformity. 8.Thou shall provide safe passage across thy roadways. 9.Thou shall provide functional connections between terrestrial and aquatic worlds. 10.Thou shall nurture the human bond with nearby nature.