habitat choice of red foxes on ocean beaches and coastal dunes… · 2019-06-05 · beaches and...

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