ACRIS Kangaroo Density Update 2004-2008
Updated information to that provided in
Rangelands 2008 – Taking the pulse
Gary Bastin, ACRIS Management Unit
CSIRO, PO Box 2111, Alice Springs NT 0871
(email: Gary.Bastin@csiro.au)
This project is supported by Ninti One Limited,
through funding from the Australian Government's Caring for our Country.
1
The views and opinions expressed in this publication are those of the authors and do not necessarily
reflect those of the Australian Government or the Minister for Sustainability, Environment, Water,
Population and Communities.
While reasonable efforts have been made to ensure that the contents of this publication are factually
correct, the Commonwealth does not accept responsibility for the accuracy or completeness of the
contents, and shall not be liable for any loss or damage that may be occasioned directly or indirectly
through the use of, or reliance on, the contents of this publication.
2
Change in kangaroo densities between 1993 and 2003 was reported for the New South Wales
rangelands and parts of Queensland and South Australia in the ‘Total grazing pressure’ section of
Rangelands 2008 – Taking the pulse (Bastin et al. 2008) (see pages 64-67).
This brief report updates changes in kangaroo density between 2004 and 2008, and also includes
information for the southern and western parts of the WA rangelands (2009 data also available for
WA).
Key points
Systematic surveys of kangaroo numbers continue across the NSW rangelands, the sheep-grazed
pastoral tenure of SA and much of western Queensland. Similar surveys also occur in the southern
and western parts of the WA rangelands and these data are now available to ACRIS.
Additional data since 2003 show that:
 The combined density of kangaroo species in WA (reds and western greys) was much lower
than the combined density of species in eastern states (including SA).
 There has been a general decline in kangaroo populations in all bioregions (with available
data for reporting) since 2003. Regional densities in 2008 were generally considerably below
the average for the 1984-93 period (used as a base for reporting change).
 Density declines were related to drier years (poorer seasonal quality) in the middle years of
the last decade. For the example bioregions examined (see Figure 5) there has been a variable
response with better seasons towards the end of the reporting period. Kangaroo densities
have remained largely unchanged in some regions and slowly increased in others.
Kangaroo management
Kangaroos are harvested in Queensland, NSW, SA and WA based on survey numbers and quotas
set by the Australian Government under the EPBC Act 1999. Harvested species include: red
kangaroos (Macropus rufus), all states; eastern grey kangaroos (M. giganteus), Queensland and
NSW; and western grey kangaroos (M. fuliginosus), NSW, SA and WA.
3
Harvest quotas are based on periodic aerial surveys, annual for most jurisdictions and triennial for
much of WA (see Figure 1). Box 1 provides more information on data sources.
Figure 1. Location of aerial
survey transects for monitoring
the density of red and western
grey kangaroos in WA. Flight
lines are separated by 0.5o of
latitude.
Note that euro monitor blocks
were not surveyed in 2010.
Map: WA Department of
Environment and Conservation.
4
Box 1. Data on kangaroo numbers
Each state monitors its kangaroo populations on a one to three year basis and harvest quotas are
generally set at between 15-20% of the estimated population of each species. Since about 1980
most states have used fixed-wing aircraft flown along set transects to monitor kangaroo numbers.
Queensland now uses helicopters for their aerial surveys.
Kangaroo density data for Queensland, NSW and SA are reported by kangaroo management zones
(alternatively, harvest zones), see Map 1. The Queensland zones approximate bioregions and in
SA, the zones are the former Soil Conservation Board districts (with survey effort concentrated
south of the Dog Fence).
Kangaroo density data for NSW data are available on-line
(http://www.environment.nsw.gov.au/wildlifemanagement/KMPPopulationEstimatesWest.htm,
accessed 20 July 2009). Updated data for SA were obtained from the Department of Environment
and Natural Resources and Queensland updates were provided by Geoff Lundie-Jenkins,
Department of Environment and Resource Management. ACRIS provided financial assistance to
the WA Department of Environment and Conservation to digitise their historic paper records.
Winston Kay subsequently supplied all available WA data (1981 to 2009) aggregated to 1o blocks
along the flight lines shown in Figure 1.
The ACRIS-MU converted kangaroo density data
from management zones to those bioregions
predominantly covered by the various zones (Map
1). Kangaroo densities were then converted to dry
sheep equivalents (DSE) for comparison with
domestic stocking densities, as per Rangelands
2008 – Taking the pulse (Bastin et al. 2008). For
current reporting, a factor of 0.35 is used to
convert the density of red kangaroos to dry sheep
equivalents (see Box 2).
Map 1. Regions surveyed for kangaroo numbers.
Map compiled by ACRIS-MU from shape files
provided by Queensland, NSW and SA agencies
contributing to ACRIS.
5
As for Rangelands 2008 – Taking the pulse, two sets of maps are used to report change:
(i)
(ii)
change in kangaroo densities by bioregion for each year between 2004 and 2008, and
the percentage change in densities between 1994 and 2008 relative to the average of the
preceding 1984-1993 period. The average for 1984 to 1993 is used as a base to accommodate
data now available from WA.
Change in kangaroo density
The combined density of red, eastern grey and western grey kangaroos was higher in the eastern states
(particularly NSW) compared with WA (Figure 2). Densities in WA bioregions were <1 DSE km-2 in
most years and maximal (at 2.1 DSE km-2) in the Central Band, Nullarbor Plain sub-IBRA between 2004
and 2006.
For Queensland, NSW and SA, the combined density of kangaroo species declined between 2003 and
2005 and then either remained relatively stable or increased (particularly in the south-eastern bioregions
of southern Queensland, NSW and eastern SA). Bioregional densities in recent years were also
considerably lower than those reported between 1993 and 2003 in Rangelands 2008 – Taking the pulse
(partly due to the lower [0.35] DSE factor). Note that scaling for the equivalent density map in that report
(Figure 3.33, page 66) was between <2 and >20 DSE km-2 (compare 0 to >5 DSE km-2 in Figure 2).
Figure 3 further illustrates that recent kangaroo densities in Queensland, NSW and SA were considerably
lower than in the 1990s and start of the last decade. Here, the yearly density for each bioregion has been
ranked against the average density for 1984-1993 (all densities reported as DSE using the 0.35 conversion
factor). Values above 100 indicate yearly densities above the base (i.e. increased density) and values less
than 100 mean a decline. The recent decline for NSW is particularly marked with individual bioregions
between 2004 and 2008 having densities of 14% to 67% of the 1984-1993 base. Most SA bioregions had
approximately 50-75% of their base density over the same period. In Queensland, densities for the two
main bioregions (Mulga Lands and Mitchell Grass Downs) declined by about a third during the 20042008 period compared with the average for the 1984-1993 base period.
Note that the scaling in Figure 3 is the same as for Figure 3.34 (page 66) in Rangelands 2008 – Taking the
pulse but the base period has been adjusted slightly to better accommodate available WA data. (The base
period for the 2008 report was 1984-91 compared with 1984-93 used here.)
There have also been recent declines in kangaroo density for most WA bioregions compared with their
1984-1993 base value. Densities reduced to as much as 30% of the base value in most bioregions in the
2004-2006 and 2007-2009 periods (and fell to as low as 15% of the base in the Pilbara). The one
exception was the Carnarvon bioregion where there has been a recent increase in density compared to the
1984-1993 base period (Figure 3).
6
Figure 2. Combined densities of three kangaroo species (red, eastern grey, western grey) in eastern,
southern and western rangeland bioregions between 2003 and 2008. Note that WA densities are for threeyear blocks,
Map compiled by the ACRIS-MU using data supplied by Queensland, NSW, SA and WA.
7
Figure 3. The percentage change in density of kangaroos between 2003 and 2008 relative to the mean
density for the 1984-1993 period.
Map compiled by the ACRIS-MU using data supplied by Queensland, NSW, SA and WA.
8
Recent declines in kangaroo density are graphed for selected bioregions in Figure 4.
% Change in Kangaroo Density (DSE) - 1984-1993 base
180
NSW Broken Hill Complex
QLD Mitchell Grass Downs
SA Gawler
WA Murchison
160
140
120
100
80
60
40
20
1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
Figure 4. Percentage changes in the combined density of three kangaroo species between 1994 and
2008 (2009 for WA) for an example bioregion in each rangeland state. Note that the WA data are
aggregated into three-year blocks. Change is expressed relative to the average density for each region
for 1984 to 1993.
Graph compiled by the ACRIS-MU using data supplied by Queensland, NSW, SA and WA.
Relative changes based on the 1984-1993 average for all bioregions with suitable data are tabulated
in Appendix 1.
Box 2. Kangaroos converted to dry sheep equivalents (DSE)
Kangaroo densities are converted to dry sheep equivalents (DSE) for comparison with domestic
stocking densities where one red or grey kangaroo equals 0.35 DSE. This factor is based on studies
of the field metabolic rate (i.e. energy requirements) of both red kangaroos and merino sheep
(Munn et al. 2008). Adam Munn (University of Sydney) advises that the same factor is appropriate
for eastern and western grey kangaroos (Adam Munn, pers comm. 2/12/2009). Adam suggests that
taking account of digestibility and feed conversion rates, kangaroos may have a slightly greater
equivalence (perhaps 0.42 to 0.45 DSE rather than the 0.35 DSE used here). Further research is
required to confirm the most appropriate DSE conversion based on feed-intake
Note that the current DSE conversion is different to that used for Rangelands 2008 – Taking the
pulse reporting (i.e. red kangaroos = 0.6 DSE, eastern and western greys = 0.5 DSE in that report).
9
Kangaroo density and rainfall
It is well known that the density of kangaroo species increases in wetter years and decreases in
droughts. Examples of changes in kangaroo density and seasonal quality were provided in
Rangelands 2008 – Taking the pulse (Figure 3.36, page 67). Further examples are provided here
(Figure 5).
In the NSW Broken Hill Complex bioregion, the combined density of kangaroos decreased sharply
between 2001 and 2003 (compared to the average for 1984 to 1993) following much below median
rainfall. Kangaroo density then increased slowly to 2008 with three of the years preceding 2008
having slightly above median rainfall.
There was a similar rapid decrease in kangaroo density with drier years between 2001 and 2003 in
both the Queensland Mitchell Grass Downs and SA Gawler bioregions. This reduced density then
more-or-less held until 2008 in both bioregions despite some better seasons in the Gawler IBRA
and progressively increasing rainfall in the Mitchell Grass Downs.
The seasonal trends were less apparent for the Murchison bioregion in WA. Kangaroo density
declined between 1998-2000 and 2004-2006 with some drier years. There was a subsequent small
increase in density in 2007-2009 with above-median rainfall.
10
120
6
5
100
4
80
3
60
2
0
140
7
120
6
5
100
4
80
3
60
2
40
1
160
8
40
1
0
20
20
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
NSW – Broken Hill Complex bioregion
Queensland – Mitchell Grass Downs bioregion
10
10
180
160
8
140
7
120
6
5
100
4
80
3
60
2
40
1
0
9
20
kangaroo density
160
8
Seasonal quality (decile rainfall)
kangaroo density
180
decile rainfall
decile rainfall
9
% of 1984-93 base kangaroo density
140
7
kangaroo density
% of 1984-93 base kangaroo density
Seasonal quality (decile rainfall)
8
180
decile rainfall
9
160
Seasonal quality (decile rainfall)
kangaroo density
% of 1984-93 base kangaroo density
9
Seasonal quality (decile rainfall)
10
180
decile rainfall
140
7
120
6
5
100
4
80
3
60
2
40
1
0
20
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
SA – Gawler bioregion
WA – Murchison bioregion
Figure 5. Changes in kangaroo densities in relation to seasonal quality indicated by decile rainfall for
four example bioregions between 1992 and 2008. Note that the WA kangaroo data are aggregated into
three-year blocks. Change is expressed relative to the average density for each region for 1984 to
1993.
Map: the ACRIS-MU. Data sources: rainfall, Bureau of Meteorology; kangaroo density, data
supplied by Queensland, NSW, SA and WA kangaroo management agencies contributing to ACRIS.
References
Bastin, G. & the ACRIS Management Committee (2008). Rangelands 2008 – Taking the Pulse.
Published on behalf of the ACRIS Management Committee by the National Land and Water
Resources Audit, Canberra. Available at:
http://www.environment.gov.au/land/rangelands/acris/index.html
Munn, A. J., Dawson, T. J., McLeod, S. R., Croft, D. B., Thompson, M. B. and Dickman, C. R.
(2008). Field metabolic rate and water turnover of red kangaroos and sheep in an arid rangeland:
an empirically derived dry-sheep-equivalent for kangaroos. Australian Journal of Zoology, 57,
23-28.
11
% of 1984-93 base kangaroo density
10
Appendix 1. Percentage changes in the combined density of three kangaroo species between 1994 and 2008 (2009 for WA) for bioregions in
each rangeland state. Note that the WA data are aggregated into three-year blocks. Change is expressed relative to the average density for
each region between 1984 and 1993.
Bioregion
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
NSW Murray
Darling
Depression
105
114
86
105
90
95
71
90
97
48
48
38
37
48
62
NSW Riverina
122
108
119
104
100
115
89
93
115
69
58
55
52
55
61
NSW Darling
Riverine Plains
78
82
56
80
110
91
106
115
148
70
49
28
42
41
40
NSW Mulga
Lands
81
79
72
102
98
87
88
120
107
38
43
38
34
39
45
NSW Simpson
Strzelecki
Desert
84
87
78
129
126
77
76
108
65
34
39
45
30
36
50
NSW Channel
Country
86
84
78
131
129
76
76
110
63
33
38
46
29
34
48
NSW Cobar
Peneplain
92
102
95
97
113
119
107
130
149
80
60
60
47
44
51
NSW Broken
Hill Complex
74
111
76
114
95
84
71
96
84
36
49
33
39
56
67
NSW Brigalow
Belt South
83
69
30
59
143
86
151
126
160
66
33
14
39
49
39
QLD Darling
Riverine Plains
51
44
60
54
84
93
94
121
161
89
83
95
91
90
85
QLD Mulga
Lands
63
58
79
80
107
133
141
178
195
107
68
88
71
77
84
QLD Mitchell
Grass Downs
115
67
94
59
113
123
152
128
124
107
66
65
77
65
83
SA Murray
Darling
121
150
171
114
101
79
79
66
120
90
84
51
56
102
89
2009
12
Bioregion
Depression
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
SA Broken Hill
Complex
103
127
128
117
138
91
88
113
69
50
48
39
37
43
42
SA Gawler
115
171
150
99
126
141
144
107
107
75
75
66
76
55
79
SA Flinders
Lofty Block
90
116
122
97
115
86
84
103
77
54
66
58
58
56
61
SA Stony Plains
(south of Dog
Fence)
85
137
129
70
89
87
122
98
102
63
65
58
58
35
39
WA Carnarvon
27
125
83
83
118
WA Coolgardie
(Eastern
Goldfields subIBRA)
56
206
118
94
74
WA Gascoyne
53
135
92
30
39
WA Murchison
51
115
100
50
59
WA Nullarbor
(Central Band
sub-IBRA)
61
64
74
95
70
WA Pilbara
36
279
46
22
15
WA Yalgoo
51
118
55
40
98
2009
13