Slow recruitment in a red-fox population following poison baiting: A non-invasive mark-recapture analysis

Oliver Berry, Jack Tatler, Stefanie Hilmer, David Algar

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Context Optimal management of invasive species should determine the interval between lethal-control operations that will sustain a desired population suppression at minimum cost. This requires an understanding of the species' rate of recruitment following control. These data are difficult to acquire for vertebrate carnivores such as the red fox (Vulpes vulpes), which are not readily trapped or observed. Aims To provide a long-term evaluation of the effects of 1080 poison baiting on the abundance and extent of movement of red foxes in a semiarid environment. Methods We used non-invasive DNA sampling of fox hairs in semi-arid Western Australia where the population was subject to two episodes of aerially delivered sodium fluoroacetate (1080) poison baits within 12 months. Sampling took place at ~45-day intervals and individual foxes were identified by genotyping eight microsatellite DNA markers and a gender-specific marker. Open-population and spatially explicit mark-recapture models were used to estimate the density, apparent survival and movements of foxes before and following baiting. Key results Following a severe reduction in density after baiting, fox density during the ensuing 12 months increased slowly (0.01foxeskm-2month-1), such that density had only reached 22% of pre-baiting levels ~10 months after the initial baiting. Moreover, recovery was non-linear as population growth was negligible for 6 months, then exhibited a nine-fold increase 7-9 months after control, coincident with the dispersal of juveniles in autumn. Fox movements between recaptures were on average 470% greater after baiting than before, in line with expectations for low-density populations, suggesting that the probability of encountering baits during this period would be higher than before baiting. Conclusions Baiting with 1080 poison significantly reduced the density of foxes, and the low density was sustained for more than 6 months. Foxes moved significantly further between recaptures after baiting when at low densities. Implications Control programs in this region may be carried out at low frequency to suppress fox density to a fraction of unbaited levels. The intensity of follow-up baiting may also be adjusted downwards, to take account of an increased probability of bait encounter in more mobile foxes. © 2013 CSIRO.
Original languageEnglish
Pages (from-to)615-623
Number of pages9
JournalWildlife Research
Volume40
Issue number7
DOIs
Publication statusPublished - 2013
Externally publishedYes

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baiting
Vulpes vulpes
foxes
bait
baits
DNA
sodium fluoroacetate
poison
analysis
sampling
carnivore
hair
invasive species
population growth
population density
gender
vertebrate
lethal genes
carnivores
Western Australia

Cite this

Berry, Oliver ; Tatler, Jack ; Hilmer, Stefanie ; Algar, David. / Slow recruitment in a red-fox population following poison baiting: A non-invasive mark-recapture analysis. In: Wildlife Research. 2013 ; Vol. 40, No. 7. pp. 615-623.
@article{461879da1a8a43eaa40e08a2dba17c90,
title = "Slow recruitment in a red-fox population following poison baiting: A non-invasive mark-recapture analysis",
abstract = "Context Optimal management of invasive species should determine the interval between lethal-control operations that will sustain a desired population suppression at minimum cost. This requires an understanding of the species' rate of recruitment following control. These data are difficult to acquire for vertebrate carnivores such as the red fox (Vulpes vulpes), which are not readily trapped or observed. Aims To provide a long-term evaluation of the effects of 1080 poison baiting on the abundance and extent of movement of red foxes in a semiarid environment. Methods We used non-invasive DNA sampling of fox hairs in semi-arid Western Australia where the population was subject to two episodes of aerially delivered sodium fluoroacetate (1080) poison baits within 12 months. Sampling took place at ~45-day intervals and individual foxes were identified by genotyping eight microsatellite DNA markers and a gender-specific marker. Open-population and spatially explicit mark-recapture models were used to estimate the density, apparent survival and movements of foxes before and following baiting. Key results Following a severe reduction in density after baiting, fox density during the ensuing 12 months increased slowly (0.01foxeskm-2month-1), such that density had only reached 22{\%} of pre-baiting levels ~10 months after the initial baiting. Moreover, recovery was non-linear as population growth was negligible for 6 months, then exhibited a nine-fold increase 7-9 months after control, coincident with the dispersal of juveniles in autumn. Fox movements between recaptures were on average 470{\%} greater after baiting than before, in line with expectations for low-density populations, suggesting that the probability of encountering baits during this period would be higher than before baiting. Conclusions Baiting with 1080 poison significantly reduced the density of foxes, and the low density was sustained for more than 6 months. Foxes moved significantly further between recaptures after baiting when at low densities. Implications Control programs in this region may be carried out at low frequency to suppress fox density to a fraction of unbaited levels. The intensity of follow-up baiting may also be adjusted downwards, to take account of an increased probability of bait encounter in more mobile foxes. {\circledC} 2013 CSIRO.",
author = "Oliver Berry and Jack Tatler and Stefanie Hilmer and David Algar",
year = "2013",
doi = "10.1071/WR13073",
language = "English",
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pages = "615--623",
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Slow recruitment in a red-fox population following poison baiting: A non-invasive mark-recapture analysis. / Berry, Oliver; Tatler, Jack; Hilmer, Stefanie; Algar, David.

In: Wildlife Research, Vol. 40, No. 7, 2013, p. 615-623.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Slow recruitment in a red-fox population following poison baiting: A non-invasive mark-recapture analysis

AU - Berry, Oliver

AU - Tatler, Jack

AU - Hilmer, Stefanie

AU - Algar, David

PY - 2013

Y1 - 2013

N2 - Context Optimal management of invasive species should determine the interval between lethal-control operations that will sustain a desired population suppression at minimum cost. This requires an understanding of the species' rate of recruitment following control. These data are difficult to acquire for vertebrate carnivores such as the red fox (Vulpes vulpes), which are not readily trapped or observed. Aims To provide a long-term evaluation of the effects of 1080 poison baiting on the abundance and extent of movement of red foxes in a semiarid environment. Methods We used non-invasive DNA sampling of fox hairs in semi-arid Western Australia where the population was subject to two episodes of aerially delivered sodium fluoroacetate (1080) poison baits within 12 months. Sampling took place at ~45-day intervals and individual foxes were identified by genotyping eight microsatellite DNA markers and a gender-specific marker. Open-population and spatially explicit mark-recapture models were used to estimate the density, apparent survival and movements of foxes before and following baiting. Key results Following a severe reduction in density after baiting, fox density during the ensuing 12 months increased slowly (0.01foxeskm-2month-1), such that density had only reached 22% of pre-baiting levels ~10 months after the initial baiting. Moreover, recovery was non-linear as population growth was negligible for 6 months, then exhibited a nine-fold increase 7-9 months after control, coincident with the dispersal of juveniles in autumn. Fox movements between recaptures were on average 470% greater after baiting than before, in line with expectations for low-density populations, suggesting that the probability of encountering baits during this period would be higher than before baiting. Conclusions Baiting with 1080 poison significantly reduced the density of foxes, and the low density was sustained for more than 6 months. Foxes moved significantly further between recaptures after baiting when at low densities. Implications Control programs in this region may be carried out at low frequency to suppress fox density to a fraction of unbaited levels. The intensity of follow-up baiting may also be adjusted downwards, to take account of an increased probability of bait encounter in more mobile foxes. © 2013 CSIRO.

AB - Context Optimal management of invasive species should determine the interval between lethal-control operations that will sustain a desired population suppression at minimum cost. This requires an understanding of the species' rate of recruitment following control. These data are difficult to acquire for vertebrate carnivores such as the red fox (Vulpes vulpes), which are not readily trapped or observed. Aims To provide a long-term evaluation of the effects of 1080 poison baiting on the abundance and extent of movement of red foxes in a semiarid environment. Methods We used non-invasive DNA sampling of fox hairs in semi-arid Western Australia where the population was subject to two episodes of aerially delivered sodium fluoroacetate (1080) poison baits within 12 months. Sampling took place at ~45-day intervals and individual foxes were identified by genotyping eight microsatellite DNA markers and a gender-specific marker. Open-population and spatially explicit mark-recapture models were used to estimate the density, apparent survival and movements of foxes before and following baiting. Key results Following a severe reduction in density after baiting, fox density during the ensuing 12 months increased slowly (0.01foxeskm-2month-1), such that density had only reached 22% of pre-baiting levels ~10 months after the initial baiting. Moreover, recovery was non-linear as population growth was negligible for 6 months, then exhibited a nine-fold increase 7-9 months after control, coincident with the dispersal of juveniles in autumn. Fox movements between recaptures were on average 470% greater after baiting than before, in line with expectations for low-density populations, suggesting that the probability of encountering baits during this period would be higher than before baiting. Conclusions Baiting with 1080 poison significantly reduced the density of foxes, and the low density was sustained for more than 6 months. Foxes moved significantly further between recaptures after baiting when at low densities. Implications Control programs in this region may be carried out at low frequency to suppress fox density to a fraction of unbaited levels. The intensity of follow-up baiting may also be adjusted downwards, to take account of an increased probability of bait encounter in more mobile foxes. © 2013 CSIRO.

U2 - 10.1071/WR13073

DO - 10.1071/WR13073

M3 - Article

VL - 40

SP - 615

EP - 623

JO - Australian Wildlife Research

JF - Australian Wildlife Research

SN - 1035-3712

IS - 7

ER -