can ingestion of lead shot and poisons change population trends of the grey partridge, common...

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

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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 :

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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