Kangaroo monitoring in relation to kangaroo management in New by lindash


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									 Kangaroo monitoring in relation to kangaroo management
                  in New South Wales
                                                      J. Gilroy
           New South Wales National Parks and Wildlife Service, 183 Argent Street, Broken Hill,
                                        New South Wales 2880

                Annual commercial cull quotas for kangaroos are based on population estimates derived
            for each o the 11 kangaroo management zones in New South Wales. The kangaroo population
            estimates are principally obtained through direct monitoring of these species by aerial surveys
            using helicopters and fixed-wing aircraft. Where mountainous or heavily wooded areas prevent
            aerial surveys, walked line transects are conducted. Experimental aerial surveys, conducted
            over three years from winter o 1998, aim to develop a new set of regional habitat correction
            factors to be applied to the results obtained from fixed-wingaerial surveys. The currently used
            200 m wide survey strip will be compared to a new 100 m wide survey strip as a part of this
            work. Since it is anticipated that this research will improve the fixed-wing aerial survey method.
            its outcomes will be adopted in the N w South Wales aerial survey programme.

                INTRODUCTION                                   tablelands a n d western slopes in the east of
                                                               the commercial zone, and part of the western
  Kangaroosare managed in New South                            plains and t h e Barrier Ranges in the west of
by the NSW                Parks and                            the commercial zone, other methods are also
Service through the NSW Kangaroo Manage-
                                                               used to monitor the kangaroo populations.
ment Program in accordance with the National
Parks and Wildlqe Act 1974. A key part of                                plains
this programme is the culling of kangaroos
undertaken mainly on a commercial basis                          From 1978 through until 1984, aerial
through the kangaroo industry. This operation                  surveys were conducted on seven randomly
occurs across approximately 600 000 km2 of                     selected monitor blocks, each represented by
the western two-thirds of New South Wales.                     a 1:250 000 m a p sheet. Kanaaroo numbers
                                                               for the whole of the westepn plains were
  The Management Program requires annual
                                                               extrapolated from the results of the monitor
population estimates for each species culled
commercially, namely the red kangaroo
                                                               blocks    u.
                                                                          Caughley et al. 1984). From 1984
                                                               onwards this survey programme was replaced
Macropus rufus, eastern grey kangaroo M.
                                                               with one comprising two transects surveyed
giganteus, western grey kangaroo M. fuliginosus,               along the 15' and 45' parallels of each one-
the common or eastern wallaroo M. robustus
                                                               degree of latitude of the whole of the western
robustus and euro or inland wallaroo M.
                                                               plains. T h e standard strip transect method
robustus erubescens. These population estimates                outlined in Caughley et al. (1977) and
are obtained principally from the direct
                                                               Caughley a n d Grigg (1981) is employed for
monitoring of the populations of these species
                                                               this survey. Over four weeks each winter,
in western New South Wales. T h e annual
                                                               a high wing aircraft is flown at a height of
commercial quotas for each species are set in                  76 m and a speed of 185 km h-' along the
relation to the population estimate.                           designated transect latitudes. Two observers,
                                                               one on either side of the aircraft, survey a
      THE KANGAROO MANAGEMENT                                  200 m wide strip on the ground for kangaroos,
              PROGRAM                                          recording the numbers seen after 97 sec. (a
  There are 11 kangaroo management zones                       distance of 5 km) during a 7 sec. break. The
in New South Wales. They are considered as                     habitat correction factors that were developed
independent management units within the                        by Caughley et al. (1976) have been used in
whole commercial zone. Each management                         determining the population estimates of red
zone has a separate population estimate for                    kangaroos a n d grey kangaroos (eastern and
each species in relation to the commercial                     western grey combined) (Fig. 1).
quotas set. A district office of the Service
                                                                 From the results of this survey, red, eastern
issues commercial Trapper licences and tags.                   grey and western grey kangaroo densities
  The principal method used to produce the                     and population sizes are estimated for each
kangaroo population estimates is aerial survey                 one-degree square block of the survey area.
with a fixed-wing aircraft. However, because                   These density estimates are then used to
of the variability in the terrain across the                   determine t h e kangaroo population size in
zones comprising part of the New England                       each management zone. To do this, the

306   Australian Zoologist 31(1)                                                                                 June   1999
                                               NSW COMBINED RED & GREY KANGAROO POPULATION ESTIMATES,
                                                      AUTHORISED QUOTA & ACTUAL CULL 1973-1999

                                 W POPULATION

    Figure I. Red and grey (western and eastern) kangaroo, combined population estimates, authorized quota and actual cull.
one-degree square block population estimates      work undertaken in Queensland (Pople et al.
are summed for each zone. If only part of         1998a,b), will compare the results of heli-
a block is within a particular zone, then a       copter line transect surveys with those of
proportion of the block estimate is used,         200 m and 100 m wide strip fixed-wing
equivalent to the proportion of the block         aircraft surveys in defined biogeographic
that falls into the zone. The relative abund-     regions of the western plains. The outcome
ances of eastern and western grey kangaroos       of this work is likely to be the adoption of
across western New South Wales were               a new set of regional habitat correction
determined from ground surveys by Caughley        factors to be applied to the counts obtained
et al. (1984). These proportions are used to      from fixed-wing aerial surveys with either the
determine the densities of each of the two        currently used 200 m wide survey strip or a
species of grey kangaroos in each one-degree      new 100 m wide survey strip.
square block. It is not possible to reliably        The Barrier Ranges euro survey was repeated
distinguish between eastern and western grey      in 1998 with some modification for improved
kangaroos from the air.
                                                  data analysis, based on the suggestions
New England Tablelands and western slopes         of C. J. Southwell (pers. comm.). Concurrent
                                                  walked line transect surveys were also
  The sizes of the eastern grey kangaroo and      conducted in the Barrier Ranges as a means
wallaroo populations in the New England           of ensuring that the bias anticipated to exist
Tablelands and western slopes were estimated      in the results of the helicopter line transect
from walked line transects conducted between      surveys of euros (Clancy et al. 1997) could
1987 and 1992 by Southwell et al. (1995).         be corrected.
The mountainous and forested areas of
the tablelands are not suitable for aerial          The New England Tablelands and western
surveys because of poor safety and visibility     slopes ground survey will also be repeated at
(Southwell et al. 1995). Since then, a combina-   a later date.
tion of anecdotal information obtained from
NPWS field staff, information obtained
from kangaroo industry returns and the results    Cairns, S. C., 1996. A review of the New South Wales
                                                      National Parks and Wildlife Service's Kangaroo Aerial
of the fixed-wing aerial surveys conducted            Survey Program. A report to the New South Wales
to the west of this area has been used to             National Parks and Wildlife Service. 27 Pp.
determine the trends in the eastern grey          Caughley, ,G., Sinclair, R. and Scott-Kemmir. D., 1976.
                                                      Expertments in aerial survey. J. Wildl. Mawgr. 40:
kangaroo and wallaroo populations.                    290-300.
                                                  Caughlci, G.,,Sinclair, R. G. and W~loon.G.. 1977. Numbers,
B a m e r Ranges                                      distrtbut~onand harvertlng rater of kangaroos on the
                                                      inland plains of New Sourh Wales. Avrl. Wildl. Rcr.
  An aerial line transect survey of euros using       4: 9 S 1 0 8 .
a helicopter was conducted in September 1993                                                   of
                                                  Caughl? G. and Grigg, G., 1981. Su~veys the distribution
by Southwell (1993). An area of 3 350 kmP             an denslttes of kangaroos in the pastoral zone of
                                                      South Australia, and their bearing dn the feasibility of
that included the Barrier Ranges was                  aerial survey in large and remote areas. Aurt. Wildl. Rcr.
surveyed. Although the target species for the         8: 1-11.
survey was the euro, data for grey kangaroos,     Caughlcy, G., Brown, B., Dastine, P. and Grice, D., 1984.
red kangaroos, emus and feral goats were also         The grey kangamo overlap zone. Aurl. Wildl. Rcr. 11:
recorded. The density and population size
                                                  Caughlq: J., Bayliss, P and Giler, J., 1984. Tmnd of kangamo
for each species was estimated. Since then,           populations in western New South Wales and their
a combination of anecdotal information                relationship to rainfall. Aurt. Wldl. Rcr. 11: 415-99.
obtained from NPWS field staff, information       Clancy, T F., Pople, A. R. and Gibson, L. A,, 1997.
obtained from kangaroo industry returns and           Camparison of helicopter line transeas with walked line
                                                      transects f o r estimating densities of Langamos. Wildl.
the results of the annual fixed-wing aerial           Res. 24: 3 9 7 4 0 9 .
surveys has been used to estimate trends in       Pople, A. R.. Cairns. S. C.. Clancy. T F., Grigg, G. C.. Beard,
the euro populations in the Barrier Ranges.           L. A. and Southwell. C. J., 1998a. An assessment of the
                                                      accuracy of kangaroo surveys using fixed-wing aircraft.
                                                       Widl. Rcr. 25: 315-26.
         FUTURE DEVELOPMENTS                      Pople, A. R., Cairns, S. C., Clancy, T F., Grigg, G. C., Beard,
                                                      L. A. a n d Southwell, C. J., 1998b. Comparison of
  In 1996 the NSW NPWS commissioned an                surveys of kangaroos in Queensland using helicopter
independent review of the kangaroo aerial                                            . I.
                                                      and fixed- win^ aircraft. Ranpcl. . 20: 92-103.
survey programme. In September 1996 the           Southwell, C., Weaver. K. E.. Cairns, S. C., Poplc. A. R.,
report (Cairns 1996) was presented to NPWS.           Gordon, A. N., Sheppard, N. W. and Broers, R., 1995.
                                                      Abundance of mcrooods in north-eastern New South
Based upon its recommendations a series of            Wales, and t h e logir6cs of broad-sale gmund surveys.
experimental aerial surveys were initiated             Wildl. Rer. 22: 7 5 7 6 6 .
across the western plains of New South            Southwell. C.. 1993. Aerial line transect estimation of euro
                                                      population size in the Barrier Ranges of wcstcrn N m
Wales starting in 1998 and continuing to              South W l e s . A report to the New South Wles National
2000. These experiments, based upon previous           Parks and Wildlife Service.

308 Australian Zoologist 31(1)

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