a demographic model for american oystercatchers in north carolina
DESCRIPTION
A Demographic Model for American Oystercatchers in North Carolina. Shiloh Schulte and Ted Simons USGS Cooperative Fish and Wildlife Research Unit, Department of Zoology, North Carolina State University, Raleigh, NC. Conservation Status. ~11,000 oystercatchers in the United States. - PowerPoint PPT PresentationTRANSCRIPT
A Demographic Model for A Demographic Model for American Oystercatchers in American Oystercatchers in
North CarolinaNorth Carolina
Shiloh Schulte and Ted SimonsShiloh Schulte and Ted SimonsUSGS Cooperative Fish and Wildlife USGS Cooperative Fish and Wildlife
Research Unit, Department of Zoology, North Research Unit, Department of Zoology, North Carolina State University, Raleigh, NCCarolina State University, Raleigh, NC
Conservation StatusConservation Status
~11,000 oystercatchers in the ~11,000 oystercatchers in the United States. United States.
~675 breeding adults in North ~675 breeding adults in North CarolinaCarolina
Threatened in Georgia, and a Threatened in Georgia, and a species of concern in Florida species of concern in Florida and Alabamaand Alabama
Threats: coastal development, Threats: coastal development, recreational activity, increasing recreational activity, increasing predator populations, pollution predator populations, pollution and destruction of food and destruction of food resources, and sea level rise. resources, and sea level rise.
AssessmentAssessment
Surveys and monitoring programs:Surveys and monitoring programs:– Valuable, but usually limited in scopeValuable, but usually limited in scope
Demographic modelingDemographic modeling– Combines vital rate estimates Combines vital rate estimates – Greater insight into population dynamicsGreater insight into population dynamics– PredictivePredictive– Determines which life stages have the most Determines which life stages have the most
influence on population growthinfluence on population growth
Modeling ObjectivesModeling Objectives
1) Quantify risks to the oystercatcher 1) Quantify risks to the oystercatcher population in North Carolinapopulation in North Carolina
2) Determine the effect of hurricanes on 2) Determine the effect of hurricanes on population trajectorypopulation trajectory
2) Identify the most critical data needs2) Identify the most critical data needs 3) Identify life stages where management 3) Identify life stages where management
actions might be most effectiveactions might be most effective
Study sites on the OuterBanks of North Carolina
Cape Hatteras National Seashore
Cape Lookout NationalSeashore
Field MethodsField Methods
Monitored 1129 nesting Monitored 1129 nesting attempts over 10 years on the attempts over 10 years on the Outer Banks of NCOuter Banks of NC
Individually banded over 280 Individually banded over 280 oystercatchers from 1999 – oystercatchers from 1999 – 20062006
Annual resight surveys to Annual resight surveys to document adult survival and document adult survival and recruitment of subadults into recruitment of subadults into the breeding populationthe breeding population
Model ConstructionModel Construction
Parameter Estimates and Data Parameter Estimates and Data SourcesSources
Adult survival: Adult survival: 0.930.93 (SE 0.013) - (SE 0.013) - Mark-resight study Mark-resight study
Fecundity: Fecundity: 0.1040.104 (SE 0.011) (SE 0.011) – Nest/chick monitoring– Nest/chick monitoring
Subadult survival with transition: Subadult survival with transition: 0.150.15 (SE 0.1) (SE 0.1) – – Ens et al. 1995, Safriel et al. 1984Ens et al. 1995, Safriel et al. 1984
Subadult survival without transition: Subadult survival without transition: 0.750.75 (SE 0.1) (SE 0.1) – Ens et al. 1995, Safriel et al. 1984– Ens et al. 1995, Safriel et al. 1984
Juvenile survival: Juvenile survival: 0.70.7 (SE 0.1) (SE 0.1) - Goss-Custard et al. - Goss-Custard et al.
1982, Kersten and Brenninkmeijer 19951982, Kersten and Brenninkmeijer 1995
Model OutputModel Output
Stable stage distribution, lambda, and matrix Stable stage distribution, lambda, and matrix element sensitivitieselement sensitivities
Added stochasticity based on standard Added stochasticity based on standard errors of parameter estimateserrors of parameter estimates
Calculated the population growth rate and Calculated the population growth rate and the probability of a 50% decline over 50 the probability of a 50% decline over 50 years based on 1000 model runsyears based on 1000 model runs
Population Trajectory: Baseline ModelPopulation Trajectory: Baseline Model
1000
800
600
400 0 50
Years
Po
pu
lati
on
Results: Baseline ModelResults: Baseline Model
Lambda: Lambda: 0.97280.9728 Probability of 50% Probability of 50%
decline over 50 years: decline over 50 years: 0.9040.904
Sensitivities: Sensitivities:
0
0.2
0.4
0.6
0.8
1
Sa F Sst Ss Sj
Hurricane EffectsHurricane Effects
Improved habitat and decreased predatorsImproved habitat and decreased predators After Hurricane Isabel, overall nest survival jumped After Hurricane Isabel, overall nest survival jumped
to 0.501 (SE 0.104, n=92). to 0.501 (SE 0.104, n=92).
0
0.1
0.2
0.3
0.4
0.5
0.6
1997 1998 1999 2000 2001 2002 2003 2004 2005
Ne
st
su
rviv
al Hurricane Isabel
Population Trajectory: Hurricane ModelsPopulation Trajectory: Hurricane Models
1000
400
800
200
600
0 50 Years
Po
pu
lati
on
0
Baseline:λ = 0.9728
15 Year Hurricane: λ = 0.9890
10 Year Hurricane:λ = 0.9983
ConclusionsConclusions The oystercatcher population in North Carolina is The oystercatcher population in North Carolina is
not self-sustainingnot self-sustaining Bonanza effects from hurricanes may mitigate Bonanza effects from hurricanes may mitigate
population decline, but are unlikely to reverse the population decline, but are unlikely to reverse the trendtrend
Management actions for maximum effect:Management actions for maximum effect:– Decrease risks to adults, especially during winter Decrease risks to adults, especially during winter
(disturbance, loss of food resources, catastrophic (disturbance, loss of food resources, catastrophic events, oil spills, etc) events, oil spills, etc)
– Increase baseline reproductive successIncrease baseline reproductive success Good estimates of Juvenile and Subadult survival Good estimates of Juvenile and Subadult survival
and dispersal are still neededand dispersal are still needed
Dissertation CommitteeDissertation CommitteeDr. Ted SimonsDr. Ted SimonsDr. Ken PollockDr. Ken PollockDr. Jim GilliamDr. Jim GilliamDr. Jaime CollazoDr. Jaime Collazo
Previous AMOY grad Previous AMOY grad students at NCSUstudents at NCSUMelissa DavisMelissa DavisConor McGowanConor McGowan
Questions?Questions?
http://www.ncsu.edu/project/grsmgis/AMOY/Research.htmhttp://www.ncsu.edu/project/grsmgis/AMOY/Research.htm