Kangaroo Population Estimates are False and Misleading

Biologically Impossible Population Increases

Research indicates that kangaroo populations increase by 10% to 13.5% under good conditions. During drought, kangaroo numbers decline by up to 65%. Joey mortality is as high as 73% in good conditions and 100% during drought.

According to the South Australian Department for Environment and Water (DEW), between 2021 and 2022, red kangaroo populations allegedly increased by 20% in Gawler Ranges, 62% in Marree (Inside Dog Fence) which wasn’t surveyed in 2022, 47% in North Flinders which wasn’t surveyed in 2022, 52% in North-East Pastoral, 24% in Eastern Districts, 41% in South Flinders and 66% in Yorke Mid-North.

Between 2021 and 2022, western grey kangaroo populations allegedly increased by 33% in Kingoonya, 49% in Gawler Ranges, 21% in North Flinders which wasn’t surveyed in 2022, 316% in Eastern Districts, 29% in Murray Mallee, 60% in Yorke Mid-North, 56% in Eyre West which wasn’t surveyed in 2022, 52% in Eyre East which wasn’t surveyed in 2022, 42% in Hills and Fleurieu and 398% in the Lower South East.

In the 2023 Quota Report, DEW stated that the increase in red kangaroo numbers was likely in response to improved environmental conditions across South Australia and that the increase in SA’s western grey kangaroo population was most likely in response to the recent high rainfall conditions across most of South Australia. The Lower South East was surveyed in May 2022. DEW alleged that western grey kangaroo numbers increased by 398% and eastern grey kangaroo numbers increased by 341%. In May 2022, the Lower South East was still experiencing serious rainfall deficiencies with some areas recording the lowest rainfall on record. It was impossible for kangaroo numbers to increase in response to rainfall. The estimated increases alleged by DEW are simply impossible.

Rainfall Deficiencies During 2021 and 2022

The above maps show serious rainfall deficiencies in the Lower South East, Upper South East, Murray Mallee, Hills & Fleurieu and Yorke Mid-North.

A combination of aerial and ground surveys (walking and driving) were used to survey kangaroo populations across South Australia between May and September 2022. During mid-August 2022, the survey plane flew in east-west transects 250 feet above the Southern Flinders, Murray Mallee, Mid North and Yorke Peninsula regions. A joey stays in mother’s pouch for up to 11 months. Spotting pouch joeys during aerial and ground surveys would be near impossible. For the purposes of checking rainfall since the last survey in 2021, we’ll go back to March 2022 because any joey born before March 2022 wouldn’t be visible in the pouch. The following table is a summary of South Australia’s rainfall since the last survey in 2021.

MonthRainfall
August 2021Below average
September 2021Very much below average
October 2021 Below average
November 2021Above average
December 2021Below average
January 2022Above average (except for southeast)
February 2022Above average/Very much below average for far west and southeast
March 2022Above average in east/Below average in central areas including the Eyre Peninsula

The following images show how rainfall deficiencies in South Australia began to improve between August 2022 and October 2022. These improvements came after South Australia’s kangaroo populations were counted, which means that “rainfall” had nothing to do with the biologically impossible increases in kangaroo numbers in South Australia.

Why Did Population Estimates Increase So Much?

The 2023 Quota Report stated: “The kangaroo industry had consistently harvested the full sustainable use quota each year since the sub-region was opened for commercial harvesting on 1 January 2020. During May 2022 DEW undertook a helicopter survey of kangaroos in the Lower South East sub-region to develop a more robust survey method for the region and re-set the sustainable use quota.” Shooters killed more than 99% of the quota on eastern grey kangaroos in 2021 and around 86% in 2022. Therefore, in 2023, DEW increased the population from 20,933 to 92,317 – an increase of 341% – so that the quota could be increased from 2,500 to 15,100. Shooters killed 66% of the quota on western grey kangaroos in the Upper and Lower South East in 2021 and 40% in 2022. Therefore, in 2023, DEW increased the Lower South East population from 7,934 to 39,565 – an increase of 398% – so that the quota could be increased from 900 to 5,900. The increase in populations are biologically impossible. No doubt DEW would say that they did a “more robust survey” in 2022 which is how they managed to find so many more kangaroos previously missed in 2021, 2020 and 2019.

The 2022 Quota Report stated: “Due to the fragmented nature of native vegetation and cover (e.g. pine plantations), kangaroos are in high numbers in relatively small areas and in low numbers across a larger proportion of the harvest sub-region.” This observation has been confirmed by local wildlife carers. The problem with kangaroos in the South East is loss of habitat which has resulted in the unnatural situation of larger kangaroo numbers in smaller areas. Curiously, the situation described in the 2022 Quota Report miraculously disappeared and suddenly, amazingly, kangaroos in the Lower South East increased from 28,867 to 131,882 – an increase of 357% – despite being fragmented with high numbers in relatively small areas and low numbers across a large proportion of the harvest sub-region.

Sorry. These increases are biologically impossible. These increases are also impossible due to the fragmented nature of native vegetation and cover (e.g. pine plantations). The increases in population were solely for the purpose of increasing the quotas. Eastern grey kangaroos and western grey kangaroos in the South East are at risk of serious decline due to excessively high quotas. The 2023 quota on eastern grey kangaroos is 72% of the 2021 population estimate and the 2023 quota on western grey kangaroos is 74% of the 2021 population estimate.

Perhaps DEW wants to seriously reduce kangaroo numbers in the Lower South East due to the fragmented nature of native vegetation and cover (e.g. pine plantations), which resulted in high numbers in relatively small areas and low numbers across a larger proportion of the harvest sub-region. The problem is that such a massive slaughter of kangaroos in the Lower South East will result in these kangaroos being at risk of extinction, especially when bushfires, floods and droughts also threaten their viability. A massive slaughter now combined with a drought next year could force these kangaroos to the brink of extinction.

The mass slaughter of kangaroos in South Australia is for the sole purpose of producing profits for a commercial industry. Sustainability doesn’t enter the equation. That’s why DEW can create ridiculous impossible population increases, to increase kill quotas, and the real number of kangaroos, the real sustainability of local populations is ignored.


Sources:
https://www.kangarooprotection.org/pages/kangaroo-ecology
South Australia in October 2021 (bom.gov.au)
Drought archive (bom.gov.au)
http://www.bom.gov.au/climate/current/month/sa/archive/202201.summary.shtml
https://www.environment.sa.gov.au/news-hub/news/articles/2022/08/kangaroo-survey-takes-to-the-sky-over-northern-agricultural-areas
https://theleadsouthaustralia.com.au/industries/regional-showcase/kangaroo-survey-takes-flight-this-month-over-south-australia/
Climate summaries archive (bom.gov.au)


Unsustainable Kangaroo Killing


Australian governments manipulate figures to give the impression that the commercial killing of kangaroos is sustainable. Australian governments hide the truth because they don’t want people to know that kangaroo populations at risk of extinction are being killed for their meat, body parts and skins or that localised extinctions are already happening. What you read in this blog is just the tip of the iceberg.

Science Ignored

Multiple scientific reports conclude that no killing should occur when kangaroo populations are less than 10 kangaroos per square kilometre.

Density of unharvested populations in these simulations rarely fell below a minimum of 5 individuals/sq km. Although the critical minimum density is not clearly defined, populations below 2/sq km would generally be considered at risk of extinction. On this basis, Figure 19 suggests that any option resulting in an average long-term density of less than 10/sq km should be rejected since in all such cases the minimum density is likely to fall below the critical level. (Kangaroo management options In the Murray-Darling Basin Hacker et al, 2004, Page 37)

Situation Analysis Report Update on Current State of Scientific Knowledge on Kangaroos in the Environment, Including Ecological and Economic Impact and Effect of Culling (Penny Olsen & Tim Low) was prepared for the Kangaroo Management Advisory Panel March 2006. The report states:

Within individual management zones, there is no need for a quota when kangaroos are above a certain density. For example, quota-free at (fictional) densities greater than 20 kangaroos/km², a quota imposed at densities between 10–20/km² and no harvesting at all below 10/km². Such thresholds would protect kangaroo populations from improving economics in the harvesting industry whereby it became profitable to harvest a greater proportion of the population than is currently economically viable. (Situation Analysis Report Update on Current State of Scientific Knowledge on Kangaroos in the Environment, Including Ecological and Economic Impact and Effect of Culling, Penny Olsen & Tim Low 2006, Page 96)

In light of the above research, kangaroos shouldn’t be killed in Western Australia or South Australia under any circumstances. Only 1 out of 7 zones in Victoria has a grey kangaroo population greater than 10 kangaroos per square kilometre. In New South Wales only 1 out of 9 red kangaroo populations is greater than 10 kangaroos per square kilometre, zero wallaroo populations are greater than 10 per square kilometre and only 7 out of 14 grey kangaroo populations are greater than 10 kangaroos per square kilometre. In Queensland, one out of 21 red kangaroo populations, one out of 21 wallaroo populations and 5 out of 21 eastern grey populations is greater than 10 kangaroos per square kilometre.  The majority of Australia’s commercially slaughtered kangaroo populations shouldn’t be killed for any reason.

Killing Kangaroos at Risk of Extinction

The Science
Density of unharvested populations in these simulations rarely fell below a minimum of 5 individuals/sq km. Although the critical minimum density is not clearly defined, populations below 2/sq km would generally be considered at risk of extinction. On this basis, Figure 19 suggests that any option resulting in an average long-term density of less than 10/sq km should be rejected since in all such cases the minimum density is likely to fall below the critical level. (Kangaroo management options In the Murray-Darling Basin (Hacker et al, 2004, Page 37)

The Reality
Red kangaroo populations generally considered at risk of extinction are commercially killed in 7 out of 17 zones in Queensland, 6 out of 9 zones in New South Wales, 6 out of 11 zones in South Australia and 3 out of 3 zones in Western Australia.

Eastern grey kangaroo populations generally considered at risk of extinction are commercially killed in 10 out of 19 zones in Queensland.

Grey kangaroo populations generally considered at risk of extinction are commercially killed in 3 out of 14 zones in New South Wales and 3 out of 7 zones in Victoria.

Western grey kangaroo populations generally considered at risk of extinction are commercially killed in 6 out of 14 zones in South Australia and 3 out of 3 zones in Western Australia.

Wallaroo populations generally considered at risk of extinction are commercially killed in 18 out of 20 zones in Queensland. New South Wales and South Australia only count wallaroo populations every three years, so current populations are unknown.


Biologically Impossible Increases

The reproduction rate for red kangaroos is a maximum of 13.5% under good conditions. The reproduction rate for grey kangaroos is a maximum of 10% under good conditions. (https://www.kangaroosatrisk.net/2-biology–population-ecology.html)

Commercial killing was suspended in Cobar in New South Wales during 2019 and 2020 due to this kangaroo population being considered at risk of extinction.

In 2020, red kangaroo numbers allegedly increased by 184%. The biologically impossible increase allowed the NSW Office of Environment & Heritage to re-open Cobar to commercial killing. The 2021 kill quota is 17,422, which is 17% of the alleged estimated population.

In 2020, grey kangaroo numbers allegedly increased by 504%. The biologically impossible increase allowed the NSW Office of Environment & Heritage to re-open Cobar to commercial killing. The 2021 kill quota is 4,421, which is 10% of the alleged estimated population.

Commercial killing was suspended in Tibooburra in New South Wales during 2019 and 2020 due to this kangaroo population generally being considered at risk of extinction.

In 2020, red kangaroo numbers allegedly increased by 153%. The biologically impossible increase allowed the NSW Office of Environment & Heritage to re-open Tibooburra to commercial killing. The 2021 kill quota is 20,046, which is 10% of the alleged estimated population.

Kangaroos in New South Wales defied science and a 3-year drought by miraculously increasing throughout the state. Red kangaroos allegedly increased by 124.7% in the Lower Darling, 103.2% in Bourke, 129.1% in Coonabarabran and 137% in Griffith South. Grey kangaroo numbers allegedly increased by 63.5% in Narrabri.


In spite of the biologically impossible increases, New South Wales kangaroo populations have declined by 40% since 2016. The biologically impossible increases suggest that kangaroo populations have declined by much more than 40%.

Since 2016, Western Australian kangaroo populations have declined by 55%, South Australian kangaroo populations have declined by 50% and Queensland kangaroo populations have declined by 36%.

In 2014, a report was prepared by the Australian Government Department of the Environment for submission to the California Department of Fish and Wildlife and included the 2013 and 2014 estimated total population of the commercially killed kangaroos in Australia. Coincidentally, during these two years, the number of western grey kangaroos increased by 116% in New South Wales, 33% in South Australia and 78% in Western Australia. In New South Wales, eastern grey kangaroos increased by 41%. In Queensland, red kangaroos increased by 42%, eastern grey kangaroos increased by 25% and wallaroos increased by 72%. In South Australia, western grey kangaroos increased by 33%.

A study of the estimated kangaroo populations in Australia over the last 20 years suggests one of three things – the method used is woefully inadequate and flawed, or the humans managing kangaroos couldn’t manage a sock drawer, or the figures are as fictional as the Harry Potter books. Maybe all three statements are true.