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Examination of bottlenose dolphin behavioural ecology using

VIEWS: 3 PAGES: 31

									       Examination of bottlenose
      dolphin behavioural ecology
     using remote sensing and GIS




Bec Donaldson                                   Dr Halina Kobryn
Veterinary and Biomedical Sciences              Environmental Sciences
Murdoch University                              Murdoch University
                          Hugh Finn
                          Biological Sciences
                          Murdoch University
                                                          Funding by
                                                          BP Kwinana
Introduction:
The application of remote sensing to studies of marine fauna is
relatively new
Remote sensing broadens the scope of behavioural and
ecological studies
The integration of data sets
   e.g. integrating:
   Data on remote sensing/ aerial photography (marine habitat information)
   with
   Field data on animals (behaviour, group size, age/sex structure of group, location,
   time)


Helps us to investigate
   conservation management questions
   such as: habitat use; location and key features of primary feeding areas; conflicts
   over area use between wildlife and humans

   theoretical ecological/ behavioural questions
   such as: social behaviour/ social structure of population
Application of remote sensing and GIS to marine
fauna research –
Case Study: Ecology and behaviour of bottlenose
dolphins in Cockburn Sound
Field data + remote sensing data were integrated and analysed in a GIS
to address:
Conservation management issues - (part A of this presentation)
   To identify key feeding habitats
   To identify frequent-use areas for mothers and calves (calves= critical
   demographic group for long-term viability of population)


Ecological/ behavioural relationships (part B)
   Novel use of GIS to investigate relationships among individuals
   e.g. Relationships between neighbouring adult male dolphins: is there a link
   between nearness of home ranges and levels of aggression between males
  Study Site:
Cockburn Sound




    Fremantle


    Cockburn Sound is 12km
    South of Fremantle




Map (left) adapted from DA Lord + Associates Pty Ltd (1998) Changes in
seagrass coverage on Success and Parmelia Banks between 1965 and 1995
Cockburn Sound has around 200
resident dolphins and is Perth’s
  main site for heavy industry
                      Field data
   900 boat-based surveys of dolphin groups




Surveys = instantaneous sample of each group including: ID of
individuals (by fin characteristics); group size; age/sex structure
(numbers of calves, sub-adults, adults); behaviour; GPS
location; date and time; environmental data e.g. presence of fish
part A: Key Feeding Habitat
GPS locations of dolphin groups displayed in
 ArcView

Data display integrated with satellite imagery* to
 identify habitats within sound (sea-grass; reef;
 shallow shelf; deep basin)

Analyses of activity budgets in each habitat
  demonstrate differential use of habitats, and
  identify areas used primarily for feeding

*ACRES LandSat 7, Mosaic of Australia, GeoScience Australia 2003
   Activities
   of dolphin
    groups

          Feed

          Rest

          Socialise

          Travel



ACRES LandSat 7, Mosaic of Australia,
GeoScience Australia 2003
Dolphin groups spent a significantly higher proportion of time feeding
when they were on the shelf than off the shelf



                                 Number of observations of dolphin groups
Activity type                     On shelf                                    Off shelf

Feed                                  142                                         31
Other activities
(rest, travel,                        539                                         215
socialise)
                     (i.e. approx. 1/4 of total was feeding)   (i.e. approx. 1/7 of total was feeding)



χ2                   d.f.                       P
8.10                 1                          0.0044


i.e. dolphins used the Shelf habitat primarily as a feeding ground
Chlorophyll a
sampling stations*




*from Kwinana Industries Council,
Australian Navy and
Cockburn Sound Management
Council

Acknowledgements also to DA Lord
and Associates and
Marine and Freshwater Research
Laboratories, Murdoch University




 Chart from Seafarer, Australian Hydrographic
 Service (Feb 2004)
   Interpolation
     of surface
   chlorophyll a
        data*
         (January 1994 data)




*data from Kwinana Industries Council, Australian Navy
 and Cockburn Sound Management Council
Use of areas within the Sound
   by mothers and calves
     Use of areas within the Sound by
           mothers and calves
Field data provided GPS locations of mothers and calves
which were displayed in ArcView

Calves were classified by age
(due to different ages having different survival risks and therefore potentially
different habitat needs, e.g. calves <1year old most vulnerable to predators)

Displays of mum-calf distributions were integrated with
LandSat images to identify shoreline and different habitats,
and
Buffers of 200m distance from the coastline were generated
from GeoScience Australia 1:100 000 coastline data, and
used to determine ‘distance-from-shore’ categories for mums
with calves of different ages
 Locations of
  females by
    calf age
         (random subset of
           4 females only)




              calf < 2 months old
              calf 2mo – 1 year
              calf between 1-2yr

              calf > 2 years



ACRES LandSat 7, Mosaic of Australia,
GeoScience Australia 2003
Females with young calves spent more time than expected near the mainland shore,
particularly on the Shelf. Females with older calves spent more time further from shore



                                  Number of observations of females with calves
 Calf age            < 2km from shore          2-4km from shore         > 4km from shore
 < 1 year old              210                        32                          5

 1-2 years                 182                        36                          15

 > 2 years                 468                       142                          52




 χ2                        d.f.                       P

 23.35                      4                       0.0001


i.e. dolphins used near-shore and Shelf habitat as a ‘nursery area’ for young calves

                                        Why?               …Prey?
….or Predators?
        (further research required)
    part B: Novel use of GIS to
  investigate social relationships
       between individuals

Q: Are neighbouring males in Cockburn
Sound friends or enemies :
The relationship between amount of home
range overlap and levels of aggression
between males
Interactions between male dolphins are
often aggressive (biting, charging, ramming)
      Relationship between range overlap and
        levels of aggression between males

GPS locations of each male from field data were displayed in
  ArcView and polygons were drawn to represent home
  ranges

Analyses of field data generated proportions of friendly and
  aggressive interactions between pairs of males
(behaviours defined as per unpubl. ethogram from the Shark Bay Dolphin Research Group)


For each male, all male associates were rated from lowest to
  highest percentage of friendly as opposed to aggressive
  interactions

This ‘friend/adversary’ scale was compared with the degree of
  range overlap for each pair of males
Case study of relationships between adult males: Hook
                                            % Level of affiliation with Hook
      Hook’s male neighbours                expressed as % friendly interactions as
      (all are resident within the Sound)   opposed to aggressive interactions

      Bundy                                 100
      Moh                                   100
      Ben                                   100
      Bat                                   93
      Ele                                   93
      Keydo                                 40
      Backpack                              33
      Mon                                   30
      Kraken                                22                                         Sample sizes N =20–50 interactions
                                                                                       per male dyad, sampled on separate
      Poseidon                              16                                         days
      Vader                                 14
      Valley                                14
      Abicus                                13
      Origami                               13

      Pocket                                0    ie all interactions were aggressive

      Calypso                               0
Hook’s range

    = Hook’s range
Bundy’s range

    = Hook’s range
    = Bundy’s range
Moh’s range

   = Hook’s range
   = Bundy’s range
   = Moh’s range
Vader’s range
Val’s range
Calypso’s range
Pocket’s range
Male “Alliances” – long term,
 cooperative relationships
between groups of 2-3 males
One function of alliances: the males work
together to compete against rival
alliances for mating opportunities
Summary




          (and the future)
                               Questions?




Acknowledgements to:
* Dr Halina Kobryn, Prof. Stuart Bradley, and the Marine and Freshwater Research Laboratories, Murdoch
University * Shark Bay Dolphin Research Group
* BP Kwinana *Kwinana Industries Council *Cockburn Sound Management Council *Australian Navy *DA
Lord and Associates *GeoScience Australia *Australian Hydrographic Service
* WA Department of Conservation and Land Management

								
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