affect the seasonal population dynamics of small mustelids? J. - - PowerPoint PPT Presentation

Do anticoagulant rodenticides affect the seasonal population dynamics of small mustelids?

• J. Fernandez-de-Simon, M. Coeurdassier, G. Couval, X. Lambin and P. Giraudoux

time Vole density

5-6 years Vole populations show cyclic fluctuations producing strong damages in agriculture properties (1)

Introduction

(1) Delattre and Giraudoux (2009)

Human-Wildlife Conflict: Anticoagulant rodenticides are used to control small mammals but these are also important for predators (2)

Introduction

(2) Delibes-Mateos et al. (2011)

Introduction

Voles controlled with anticoagulant rodenticides can indirectly poison predators (3, 4). Are there any effects at the population level?

(3) Grolleau et al. (1989), (4) Coeurdassier et al. (2014), (5) Jacquot et al. (2013), (6) Murphy et al. (1998)

Foxes in Franche-Comté (5) Stoats in New Zealand (6)

Introduction

Objective: To study if bromadiolone affects small mustelid populations. Hypothesis: Bromadiolone decrease mustelid population change. Prediction:

• Mustelid population decrease at treated sites.
• Conditional to food availability (water voles).

= Low frequency or no use of bromadiolone (6 sites)

• Methods. Selection of study sites

= High frequency of use of bromadiolone (4 sites) Data of bromadiolone treatment by (7)

(7) Jacquot et al. (2013)

• Methods. Estimation of small mustelid

abundance

50 footprint tracking tunnels per site (8) Seasonal population change = Ln (Autumn / Spring footprints)

(8) King and Edgar (1977)

Surveyed for each site in:

• Spring 2016
• Autumn 2016

• Methods. Estimation of vole density

Estimation of density by conducting transects on foot, 6 agricultural parcels per site (9) % of sections with presence of water voles

(9) Giraudoux et al. (1995)

Data analyses

Linear model of variables related to mustelid dynamics Response: Seasonal population change Predictors:

• Treatment frequency (High/Low)
• Vole density (log-transformed)
• Treatment frequency * Vole density

P-value of model and variables; R2

Results: bromadiolone

Bromadiolone use in 2016 for sites with high frequency of treatment

200 400 600 Jan-16 Mar-16 May-16 Jul-16 Sep-16 Nov-16 Bromadiolone (kgs.)

GILLEY

200 400 600 Jan-16 Mar-16 May-16 Jul-16 Sep-16 Nov-16 Bromadiolone (kgs.)

FUANS

Repeated treatment, summer peak Repeated treatment, autumn peak

Results: bromadiolone

Bromadiolone use in 2016 for sites with high frequency of treatment

200 400 600 Jan-16 Mar-16 May-16 Jul-16 Sep-16 Nov-16 Bromadiolone (kgs.)

BOUJAILLES

200 400 600 Jan-16 Mar-16 May-16 Jul-16 Sep-16 Nov-16 Bromadiolone (kgs.)

HAUTEPIERRE

Repeatedly, Spring treatment peak Treatment only in Autumn

Results: small mustelids

• 10
• 5

5 10 ASM BB VER CB ASC EVI HLC BOU FUA GIL Seasonal population change of small mustelids Low frequency or no bromadiolone High frequency of bromadiolone All sites with bromadiolone frequently used showed negative seasonal population change

Results: water voles

Low frequency or no bromadiolone High frequency of bromadiolone High variation, but two sites with frequent bromadiolone use recorded the lowest densities 20 40 60 80 100 BOU HLC GIL FUA ASM EVI CB VER ASC BB Vole density (%)

Results: linear model

Estimate

• Std. Error

t value P-value (Intercept)

• 15.986

2.378

• 6.723

0.001 *** Low bromadiolone 16.687 3.801 4.39 0.005 ** Log Water vole density 10.941 2.169 5.044 0.002 ** Interaction Bromadiolone use * Vole density

• 11.177

3.15

• 3.548

0.012 * Model correlation coefficient, R2 = 0.9 Model P-value = 0.001 All variables were significant

Results: mustelids and treatment

Mean seasonal population change was negative in sites with high frequency

• f bromadiolone

treatment

• 8
• 6
• 4
• 2

2 4 6 8 Sites with high frequency

• f bromadiolone

treatment Sites with low frequency

• r no bromadiolone

treatment Seasonal population change of small mustelids

Results: small mustelids and voles

At sites with high frequency of bromadiolone treatment (red points), population change was positively associated with water vole density.

• 10
• 5

5 10 10 20 30 40 50 Seasonal population change

• f small mustelids

Water vole density (% presence)

Discussion

• Bromadiolone may affect mustelid dynamics (10).
• Extreme mustelid declines at treated sites with the lowest vole densities (food

scarcity/intoxication, 11, 12).

• Next steps: bromadiolone analyses in voles (13) and mustelid scats (14).

(10) Murphy et al. (1998), (11) Gilg et al. (2003), (12), Grolleau et al. (1989), (13) Sage et al. (2008), (14) Sage et al. (2010)

Merci! Thanks! ¡Gracias!

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