SAMBAR NUMBERS REVISITED

This is invariably followed by the statement that “Recreational hunting alone cannot control sambar numbers”. The ‘failure’ of recreational hunters to control deer, along with feared or actual environmental damage, is then used to justify the side-lining of hunters by government, the downgrading of the status of the deer, research into new control methods and deer culling by paid shooters.

Just what evidence the often cited ‘million sambar’ is based on is not clear, but it is likely that many commentators have chosen it as it has a scary ring to it – great to paint a picture that if something isn’t done about the sambar, terrible impacts will result!

So, beyond all of the hype and angst, what do we really know about sambar numbers and trends and what are the implications for their management and for the future of recreational hunting?

Early Speculation

Bentley (1978) records that sambar were released in eastern Victoria from the mid-1860s. Sites included Tooradin, Snake Island, Kinglake and possibly Jamieson. By the 1880s it was suggested that the sambar near Tooradin then numbered “some hundreds.”

Bentley went on to suggest that in 1978 the forested habitat of West Gippsland probably had a sambar population density of one animal per 6.4km 2. Using this population density, and suspecting that at this time the sambar had occupied around 23,000km 2 of eastern Victoria, he estimated the deer population to be around 3,600 animals.

ADA Surveys

From 1977 through until 1994 the ADA, with advice from wildlife biologist Graham Caughley, ran an annual survey of its Victorian members to gather information on the sambar hunting effort and deer harvest. At the time this was considered important as it wasn’t known whether deer numbers were increasing, decreasing or stable and whether the hunting was sustainable over the longer term (White 2023).

If over time the harvest of deer taken per hunting day changed, this would be an indicator of change in the population (in effect an ‘index’ of deer numbers).

Ninety to 95 per cent of survey respondents hunted each year. Hunter success did not change over the 18 surveyed years. The average active stalker took less than one deer (0.6) annually while the average active hound hunter, who hunted more frequently, took 1.6 animals per year. Stalkers tended to focus on shooting stags while leaving hinds and calves, while hound hunters shot whatever deer were pushed out by the hounds. Given that there were similar numbers of stalkers and hound hunters the overall take of deer was around one per hunter per year, with a slight preponderance of stags taken over hinds.

Between 1977 and 1994 the number of licensed hunters increased from 2,000 to 7,000. If respondents to the survey were representative of all licensed hunters at the time, it is likely that the annual harvest of sambar increased from around 1,800 in 1977 to around 6,650 in 1994. If a harvest of 25 per cent of a deer population is sustainable (Watter and others 2020), this implies that the sambar population rose from at least 7,200 in 1977 to at least 26,600 in 1994.

Upper Yarra Dam Survey

In 2003, Parks Victoria commenced an investigation into sambar numbers around the Upper Yarra Dam in the Yarra Ranges National Park because of concern about their effect on water quality in the dam. The study was based on the rate at which deer defaecate, the accumulation of faecal pellets in plots and the time it took for pellets to decay (Houston 2005). This technique is most often used to derive an ‘index’ of deer numbers rather than an actual number.

However, in this instance an attempt was made to estimate deer numbers in two habitat types; grassland on the dry bed of the reservoir and in the adjacent forest. Sambar population densities were estimated at 231 to 426 animals/km 2 on the grassland and 54 to 100 animals/km 2 in the forest!

Game Management Authority Surveys

Since 2009 the Victorian GMA, in cooperation with staff at the Arthur Rylah Institute (ARI), has collected and analysed information on recreational deer hunting in the state. Reports have been published covering the years 2009 through to 2022.

Licensed deer hunters are randomly sampled and interviewed by telephone at intervals during the year. Respondents are asked the number and sex of sambar (and other deer) that they had harvested. Information is also obtained on hunting methods and days hunted. Since 2017 another group of licence holders have also been asked whether they hunted during the year to determine the percentage of ‘active’ hunters.

Like the ADA surveys conducted between 1977 and 1994, the GMA surveys quantify the hunting effort and the average number of deer harvested per hunting day by stalkers and hound hunters. A total statewide recreational harvest of sambar by all hunters can also be calculated. In theory, the harvest per hunting day and the total harvest both provide an index of sambar numbers in the areas that can be legally hunted.

The calculated recreational take of sambar between 2009 and 2022 is represented in the graph. Over those years the number of licensed deer hunters more than doubled from 19,949 to 50,478. Meanwhile, deer distribution likely increased and the major wildfires that occurred in 2003, 2006, 2009, 2012 and 2019/2020 would have initially reduced deer numbers in the areas burnt but then seen them increase as the forest recovered and the deer took advantage of excellent feeding and breeding conditions.

The sambar harvest identified by the GMA surveys between 2017 and 2022 ranged from an average of 3.1 to 5.4 animals per active hunter per year, far higher than found by the ADA surveys.

The GMA has never used their harvest surveys to estimate the sambar population in Victoria. However, again using the abovementioned sustainable take of 25 per cent of the population, these harvest figures imply that the sambar population where hunting is allowed must have numbered at least 130,000 in 2009. If the sharp peak of 2019 and the Covid 19 impacted years of 2020 and 2021 are considered outliers, a population of over 360,000 is implied more recently.

If the area of public land in Victoria occupied by sambar is 39,000km 2 (Cally and Ramsey 2023), of which approximately 5,000km 2 is in parks closed to hunting, and given a deer population of around 360,000, this implies an average population density of one sambar per 9.4ha of public land or 10.6 deer/km 2.

Application of Science

Bengsen and others (2022) used trail cameras (they called them camera traps) to take photographs of deer between 2017 and 2019 and used the information gained to calculate the number of animals present in an area. They estimated sambar densities to be 0.7/km 2 and 2.5/km 2 (one per 143ha and one per 40ha respectively) in two areas of the Kosciuszko National Park. Whether these populations were long-established and likely to be stable was not stated. High-fenced water catchments near Melbourne were also investigated and population densities of 3.9 and 11.9 sambar/km 2 were found.

Between September 2021 and May 2023 camera traps supplemented by sign surveys were used to investigate deer numbers in Victoria (Cally and Ramsey 2023). These authors concluded that there were around 123,000 sambar on public land in Victoria (likely range 96,000 to 158,000) occupying around 39,000km 2 or 3,900,000ha (likely range 33,000 to 41,000km 2 ). A sambar population of 123,000 occupying 39,000km 2 equates to 3.2 animals/km 2 or one animal per 32ha of public land. Ramsey suggests (personal communication 2024) that this survey would have included the sambar living on public land that feed onto private land between dusk and dawn.

Ramsey and others (2023) reported on the helicopter culling of deer in ten parks in eastern Victoria undertaken between February 2020 and May 2022. These culls followed major wildfires in 2019/2020 that impacted these areas. They used the information obtained during the cull to estimate the initial densities of sambar, concluding that they ranged from 0.1 to 2.8 deer/km 2 and averaged around one animal/km 2.

Discussion

The apparent rapid increase of sambar numbers near Tooradin in South Gippsland between their release in the 1860s and the 1880s was an indication of what the future held – they were obviously well-suited to the environment that they found themselves in. Ninety years on, in 1978, Bentley’s assessment that the sambar population might have increased to around 3,600 head seems in retrospect to be conservative and was undoubtedly well short of the true number at that time.

The ADA’s sambar surveys aimed to develop an index of deer numbers. It soon became apparent that as the number of hunters increased, the harvest of around one deer per year per hunter did not change – hunting was having little or no impact on the sambar population. When the surveys started in 1977 the sambar population had to be greater than 8,000 (probably much greater) and by 1994 the population undoubtedly numbered in the tens of thousands.

The investigations into sambar numbers in closed or high-fenced water catchments near Melbourne indicate that localised high sambar population densities can occur under some circumstances. However, such situations are irrelevant to the majority of eastern Victoria’s sambar range and aren’t helpful in defining population numbers.

When the GMA surveys commenced in 2009 two results stood out compared with the ADA surveys of previous decades: the total number of sambar harvested each year and the number shot by each active hunter. If these results were valid, the sambar population was no longer in the tens of thousands, but rather in the hundreds of thousands and active hunters, for whatever reasons, were apparently finding it easier to harvest these very elusive deer.

But were these GMA survey results valid? There are many reasons why licence holders would deliberately overstate their harvests while there are no obvious reasons for them to understate their take. Memory lapses, misunderstandings and hostility to the GMA might also skew individual harvest reports, probably also resulting in over reporting of harvests.

Many wildlife managers have studied the reliability of hunter surveys (for example Kilpatrick and others 2005), and ‘prestige bias’ – over-reporting harvests or altering sex or age, ‘response bias’ – incorrect reports by mistake or by survey design and ‘recall bias’ – failure to correctly recall hunts, are recognised issues that can lead to incorrect conclusions.

Although it is possible that a growing sambar population and advances in equipment and hunting techniques may have influenced hunters’ success rates, it seems remarkable that the harvest per hunter per year had increased to the extent reported. Again, this points to the likelihood that the GMA survey harvests may be overstated and implying a sambar population that is higher than reality!

Cally and Ramsey (2023) and Ramsey and others (2023) have assessed sambar numbers on public land and suggested that they probably fall within the range of 96,000 to 158,000 at a population density of around three animals/km 2 of habitat. A sustainable annual harvest given this population, allowing for a 25 per cent take per year, would be in the order of 24,000 to 40,000 animals, far fewer than suggested by the GMA surveys. As the vast majority of sambar live on public land, this sustainable harvest would not be significantly affected by the small numbers living exclusively on private land.

The average of three sambar/km 2 of public land suggested by Cally and Ramsey (2023) also seems reasonable from a hunter’s perspective and probably reflects the average ‘carrying capacity’ of eastern Victoria’s eucalypt forests.

Conclusions

Since their liberation in the 1860s sambar have bred and colonised widely and now number in the low hundreds of thousands across eastern Victoria. However, statements that they now number “one million” are clearly wrong. The assertion that numbers are “still increasing” is also doubtful as they have probably now reached ‘carrying capacity’ across the majority of their range.

A key question that arises is, “Can the GMA harvest numbers and scientific reports of deer numbers be reconciled?” In my opinion the answer is clearly “No!”. The GMA harvest numbers are almost certainly too high while the reports of Bengsen and others (2022), Cally and Ramsey (2023) and Ramsey and others (2023) are more likely to be an accurate reflection of sambar numbers. The GMA survey needs to be reviewed to identify ways in which it can be improved.

While the sambar population is apparently much smaller than has been commonly portrayed, it doesn’t change the need for the species to be managed to minimise any negative impacts while maximising its value to the community. One thing is certain: these deer can never be eradicated. The question, given this new reality, is “What can be done to best utilise recreational hunters to better manage these lower sambar numbers and thereby reduce the need for expensive taxpayer-funded culling?”

Giving the Game Management Authority the legal ability to promote recreational hunting would be an excellent first step. Opening all currently closed remote parks to recreational deer hunting (Snowy River National Park being a prime example) would be an excellent second, but by no means, final step. We can only dream!

References