Source Sink Dynamics in Neotropical Migratory Songbirds

Calandra Stanley

Outline:

• Review of Metapopulation Ecology and Source-Sink Dynamics

• Examples of Sources and Sinks

• Current Limitations of Source-Sink Models

• Future Directions

Source Sink Dynamics in Neotropical Migratory Songbirds

Metapopulations: Population of Populations (Levin 1969)

Derived to describe spatially-structured populations

Local populations inhabit discrete habitat patches. Eg. Fragments

These local populations are connected through migration between patches

…Recall Chapter 5?

Metapopulations: Sources and Sinks (Pulliam 1988)

Sink

Sink

Sink b < d e < i

Source b > d e > i

Source

Source: net exporter of individuals

Sink: net receptor of individuals

Source-sink dynamics arise when surplus reproduction from a source maintains a positive population in a sink

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Source-sink Dynamics as a Management Tool

Analyzing declines in Neotropical Migratory Songbirds

Identifying Sources and Sinks

• Burke and Nol (2000) identified if fragments of different size served as sources or sinks

• Monitored nesting success of 5 species of interior forest songbirds in southern Ontario

Identifying Sources and Sinks

Fauth 2000

Local: Wood Thrush demographics in Northern Indiana fragments

Continental: Use of predictive models to detect relationship between fragmentation and population growth

Llyod et al 2005

Limitation to Pulliam’s Model

• Actual measures of source-sink dynamics largely lacking • Difficulty estimating parameters • Assumes equilibrium Ignores dispersal Solutions: Runge et al 2005 suggests use of a different metric to define sources and sinks • Cr = per capita contribution of a member of the focal

subpopulation to the metapopulation

Source-Sink Dynamics: Wood Thrush

Titler et al. (2006) assessed sources and sinks using measures of asynchronous dispersal

Thank You!

Hanski I. 1998. Metapopulation Dynamics. Nature. 365: 41-49.

Fauth PT. 2001. Wood thrush populations are not all sinks in the agricultural Midwestern United States. Conservation Biology 15:523–527.

Lloyd P, Martin TE, Redmond RL, Langner U and Hart MM. 2005. Linking demographic effects ofhabitat fragmentation across landscapes to continental source-sink dynamics. Ecological Applications 15: 1504-1514.

Pulliam HR. 1988. Sources, sinks, and population regulation. American Naturalist 132: 652-661.

Pulliam HR. 1993. Sources and sinks: empirical evidence and population consequences. In Population dynamics in ecological space and time. Rhodes OE, Chesser RK and Smith MH (Eds). The University of Chicago Press, Chicago, IL. Pp. 45-69.

Robinson SK, Thompson FR, Donovan TM, Whitehead DR and Faaborg J. 1995. Regional forest fragmentation and the nesting success of migratory birds. Science 267: 1987-1990.

Runge, JP, MP Runge, JD Nichols. 2006. The Role of Local Populations within a Landscape Context Defining and Classifying Sources and Sinks. The American Naturalist. 167: 925-938

Runge MC, Marra PP. 2005. A demographic model for a migratory passerine bird: population dynamics of the American redstart. In Birds of Two Worlds: The Ecology and Evolution of Temperate-Tropical Migration. Greenberg R and Marra PP (Eds). Johns Hopkins University Press, Baltimore. Pages 375-389.

Tittler R, Fahrig L and Villard MA. 2006. Evidence of large-scale source-sink dynamics and longdistance dispersal among wood thrush populations. Ecology 87: 3029-3036.

Identifying Sources and Sinks

Robinson et al 1995 Fauth 2000

Local: Wood Thrush demographics in Northern Indiana fragments

Regional: Habitat-specific fecundity in fragments across the Mid-West, 8 species

Identifying Continental Sources and Sinks

Llyod et al 2005

Use of predictive models to detect relationship between fragmentation and population growth

What about the non-breeding season?

Runge and Marra 2005