can ingestion of lead shot and poisons change population trends of the grey partridge, common...
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CAN INGESTION OF LEAD SHOT AND POISONS CHANGE POPULATION TRENDS OF THE GREY PARTRIDGE, COMMON BUZZARD, AND RED KITE?
© Arcadis 2015
Lead shot ingestion by upland birds
Little is known of its effects on
• Population size• Population growth
• Extinction rate
Plus pesticides, bait poisons
Effect of these multiple chemical stressors on populations is unknown
Question: How might lead shot and poison ingestion change populations of susceptible species?
Lead Shot & Poison in Small Game Hunting Areas
© Arcadis 2015
Study ObjectiveDemonstrate how population models can be used to evaluate combined effect of lead shot and poison ingestion on susceptible upland bird populations in Europe using
• pathology reports that diagnose cause of death
• population models
Susceptible species
Granivores
Scavengers
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Study Areas and SpeciesData for Population Model Parameters:• Grey Partridge
- Continental Europe (lead shot & poison present)• Common Buzzard
- Germany (mostly poison present)• Red Kite
- Wales (mostly poison present)
Data for Lead Shot/Poison Effects (highest impacted areas): • Grey Partridge
- England and France (both stressors present)• Common Buzzard
- England (both stressors present)• Red Kite
- England (both stressors present)
Must add or subtract lead shot/poison mortality using joint probability equations to model effects
Methods
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Causes of Death for Grey Partridge
40%
11%5%
24%
9%
7%11%
Ultimate Causes
Predation
Starvation/Disease
Accident/Mowing
Hunting
Pesticide Poison
Lead Shot Ingestion
Unknown
Direct Reported: From pathologist
Ultimate Cause: Based on percentage with elevated subclinical lead or poison even if reported as died of another cause
Direct = Lower Bound, Ultimate = Upper Bound, Midpoint = best estimate
41%
5%7%
25%
6%
4% 12%
Direct Reported CausesUK, France: n=775
Predation
Starvation/Disease
Accident/Mowing
Hunting
Pesticide Poison
Lead Shot Ingestion
Unknown
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Causes of Death for the Raptors
29%
46%
9%
4% 13%
Direct Reported CausesUK: n=56
Starvation/DiseaseAccident/TraumaShot by GunBait PoisonLead Shot IngestionUnknown
15%
26%
4%
46%
9%
Direct Reported CausesUK: n=44
Starvation/Disease
Accident/Trauma
Shot by Gun
Bait Poison
Lead Shot Ingestion
11%
23%
4%46%
16%
Ultimate Causes
Starvation/DiseaseAccident/TraumaShot by GunBait PoisonLead Shot Ingestion
27%
45%
9%
4% 5% 11%
Ultimate Causes
Starvation/DiseaseAccident/TraumaShot by GunBait PoisonLead Shot IngestionUnknown
Common Buzzard Common Buzzard
Red KiteRed Kite
(a) (b)
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Grey Partridge Population Model Used Published Model: DeLeo et al. 2004
Population Viability Analysis Model
• Developed for European continent from 1965 to 1993• Seasonal model (spring, summer, autumn/winter)
• Spring population growth rate and survival are density dependent• Environmental stochasticity• Mortality from lead shot and poison ingestion subtracted from baseline
ln(spring growth rate)
Autumn/winter mortalityAnnual population growth rate, r
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Common Buzzard Population Model :
)()()()(
000000000
)1()1()1()1(
3
2
1
0
2
1
0
3210
3
2
1
0
tNtNtNtN
SS
SFFFF
tNtNtNtN
Matrix Population Viability Analysis Model in PopTools
• Age-structured, pre-breeding matrix• Annual time step• Density dependence of survival, fertility• Environmental stochasticity
• Added lead shot and subtracted poison mortality from baseline
Theta-logistic equation used to model density dependence
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Red Kite Population Model :Matrix Population Viability Analysis Model in PopTools
• Age structured, pre-breeding matrix• Annual time step• Density dependence of survival and fertility• Environmental stochasticity• Added lead shot and subtracted poison mortality from baseline
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Common Buzzard
Baseline Model Output Similar to Observed Data
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Red KiteBaseline Model Output Similar to Observed Data
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• Observed Partridge • Modeled Partridge
Steady state equilibrium population size (horizontal line) is mean of 10,000 model runs
Baseline Model Output Similar to Observed Data
Results
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Grey Partridge• 4 Scenarios Modeled
Combined reduction in steady-state population size from the 2 stressors is 18%
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Common Buzzard
Steady-state equilibrium population size (horizontal line) is mean of 10,000 model runs
Combined reduction in steady-state population size from the 2 stressors is <1%
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Red Kite
Adding lead shot ingestion reduces annual growth rate from 6.5 to 4%
Removing bait poison increases annual growth from 6.5 to 12%
Population is growing in all scenarios
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Conclusions
Lead shot and poison ingestion did not change direction of trends but
• Lead shot reduced declining partridge population by additional 10% and with addition of poisons by 18%
• With both stressors, probability of quasi-extinction (to < 5 birds/km2) increased for partridge from 4.5% to 16%
• Lead shot and poison reduced large, stable buzzard population size by less than 1%
• Lead shot reduced annual growth rate of the red kite from 6.5% to 4%; this rate would have been 12% with bait poisons removed
• Declining or recovering populations are most sensitive to these chemical stressors
These reasonable worst-case models have much uncertainty but demonstrate an approach to quantify impacts
AcknowledgmentsFunding:AEFMS, ARCADIS, ERM, ARCHE
People:Margaret BarteeMichele Buonanduci
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Questions/Discussion
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Thank you!
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CAROLYN MEYERTechnical Expert/Ecologist
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JOSEPH MEYERTechnical Expert
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ALEX FRANCISCOPrincipal Ecologist
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JENNIFER HOLDERPartner/Principal Scientist
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FREDERIK VERDONCKScience Project Manager