Upload
others
View
2
Download
0
Embed Size (px)
Citation preview
Habitat Choice of Red Foxes on Ocean Beaches and Coastal Dunes: Habitat
Generalists or Nuanced Use?
Olivia KimberProf. Thomas Schlacher, Dr. Ben Gilby, Dr. Andrew Olds
The Red Fox
Red fox(Vulpes vulpes)
Arctic
Woodland
Desert
Forest
Ocean beach ecosystems
Habitat Selection
No study has comprehensively assessed
red fox habitat selection along ocean
beaches
- Foxes commonly occur on beaches
- Foxes impact beach fauna
- Uniform landscape, fauna affected by
landward habitat
Habitat Selection
What features have previously been
identified to shape fox distribution?
Literature synthesis:
• 221 potential articles
• Summarised 73 habitat selection articles
• 106 different predictor variables identified
• Determined positive ( ), negative ( ), or no
association (-) with fox distribution
Habitat Selection
Literature synthesis results: generally no
consensus on fox habitat selection
For example
Urbanisation: -
Farmland: - - - - - - -
Grassland: - - - - - - - -
Shrubland: - - - - - -
Heathland: - -
Wetland: - - - - - - - -
Water body: - -
… 106 environmental variables
Research Question
Do red foxes have any associations with
the landscape attributes of beaches and
coastal dunes?
Aim:
To determine what features of coastal ecosystems
shape the distribution of foxes along ocean
beaches
Hypothesis:
It is predicted red foxes have few associations
with the landscape attributes of beaches and
coastal dunes
Study area:
• South East Queensland, Australia
• ~108km: Double Island Point to Caloundra
• Ideal coastline to study fox habitat selection
Study site selection
• Stratified random distribution of sites
• 192 sites
Study Design
Site Design
• 2 cameras (one video, one photo)
• Baited with mullet (Mugil cephalus)
• Deployed for 48 hours
• Bait and SD cards replaced every 12 hours
Methods
Camera mode (3 photo burst) Video mode (10 seconds)
Methods
Environmental Variables
Initial variables
• Urban land cover*• Distance to human settlement• Domestic dogs• Total road length*• Number of access points*• Reserve area*• Forest cover*• Distance to estuary• Low lying areas/wetlands*• Water body*• Dune height• Terrain rugosity*• Fox control type*• Fox removal*
* Within a 1.6 Km radius of the site
Urban landscapes
Connectivity
Geomorphology
Fox control
Environmental Variables
Initial variables
• Urban land cover• Distance to human settlement• Domestic dogs• Total road length• Number of access points• Reserve area • Forest cover• Distance to estuary• Low lying areas/wetlands• Water body• Dune height• Terrain rugosity• Fox control type • Fox removal
Urban landscapes
Connectivity
Geomorphology
Fox control
Environmental Variables
Excluded variables
• Distance to human settlement
• Total road length
• Reserve area
• Forest cover
• Distance to estuary
• Fox control type
Reason for exclusion:
• Pearson’s correlation coefficient > 0.7
• More support in the literature, and/or
• More relevant to the coastal ecosystem
studied
Environmental Variables
Remaining variables
• Urban land cover
• Domestic dogs
• Number of access points
• Low lying areas/wetlands
• Water body
• Dune height
• Terrain rugosity
• Fox removal
Data Analysis
Modelling
• Generalized additive model (GAM)
• Fox presence/absence at site over two
consecutive nights (binomial)
Model simplification
• Multi-model inference (dredge function)
• Best fit: delta Akaike Information Criterion (AIC)
values < 2
• Weighted AIC to determine importance
Results
Fox control/removal
• Analysis on south of Noosa only (114 sites)
• Determined to be the least important predictor
• Importance = 0.17, p-value = 0.18
• Fox control excluded from further analysis
Mullet weight
• Mean weight = 531 g, s.e. = 3.68
• Generalised linear model
• Did not significantly influence fox presence
• P-value = 0.19
Double Island Point to Noosa River (78 sites)
56 x 72% of sites had foxes
Noosa River to Caloundra (114 sites)
41 x 36% of sites had foxes
Results: Occupancy
Double Island PointDouble Island Point to Noosa River (78 sites)
56 x 72% of sites had foxes
Noosa River to Caloundra (114 sites)
41 x 36% of sites had foxes
Results: Occupancy
Model Variable 1 Variable 2 Variable 3 Variable 4 df ∆ AICc
1 Dune height * Urban land cover * Terrain rugosity * Water body ns 9 -
2 Dune height * Urban land cover * Terrain rugosity * 8 0.79
3 Dune height * Urban land cover * Terrain rugosity * Domestic dog presence ns 9 0.90
4 Dune height * Urban land cover * Terrain rugosity * Number of access points ns 9 1.10
Results: Model Selection
Results: Directionality
Results: Heat map
Double Island Point
Teewah
Teewah
Noosa
Coolum
Coolum
Maroochydore
Caloundra
Results: Heat map
Double Island Point
Noosa
Coolum
Coolum
Caloundra
Discussion: Dune Landforms
Dune height & terrain ruggedness:
• More foxes in areas with tall continuous
dunes
• These dunes may restrict foxes to linear
ranging along the beach
• Preferred denning conditions (sandy,
well-drained soil)
• Wind dynamics allow easier detection of
bait
Discussion: City Foxes
Urbanisation:
• Fewer foxes in more urbanised areas
• Few suitable denning areas.
• Influence of domestic dogs (in
backyards)?
• Are small coastal reserves harbouring
urban foxes?
Discussion: Fox Management
Fox control:
• No significant effect of current fox
control practices
• Recruitment by foxes into vacated
territories?
• Necessity for landscape-scale land
management
Conclusion
First comprehensive assessment of fox habitat associations in coastal zone.
Red foxes have clear associations with the landscape attributes of beaches and coastal dunes.
Thank You