Rhino Numbers and Census

[Lisbeth]

As already stated, those figures are certainly not 100% correct and not very detailed either. There are quite a few "mortality unknown" for instance. Too many!

[Klipspringer]

Any survey technique carries errors which influence the precision of estimates, that's why these stats are estimates (but not guesswork).

[RobertT]

What is does show is that they have been in the negative vs births for years with poaching and natural deaths, even though SANParks has been saying otherwise.

[Richprins]

I think part of the idea was also to show drought deaths for 2016/17...which didn't really happen IMO...

[Richprins]

An unpublished study by Dr Joubert:



WHERE HAVE ALL THE RHINOS GONE

SCJ Joubert, 29 October 2018

In a document submitted to research officers at Skukuza in October 2015 it was pointed out that the rhino population had reached the “dreaded tipping point” where the numbers poached exceeded the recruitment rate. In fact, during an interview with a journalist in 2013 I had expressed the opinion that such an unfortunate situation had already been reached.

This statement elicited a sharp response from SANParks in which it was stated that “it is important to stress that we have not yet reached the point where … the Kruger’s rhino population is declining. The rate of loss of white rhino in the Kruger National Park stood at 3.8% of the total population in 2012, and this is expected to rise to around 5.5% in 2013. While this is a considerable escalation in the loss rate, it has not yet reached the rate of natural increase … which stands at 8% …”

SANParks’ statement also quoted Dr Sam Ferreira: “the white rhino population in the Kruger National Park will begin declining in 2016 if the present rates of increase in poaching continue. It is important to note in this regard that 12 of the 35 landscapes in the Kruger National park had seen a stabilization of rhino populations due to density-dependent ecological processes. According to Dr Ferreira the removal of a number of rhino from these landscapes could induce localized higher population growth thus compensating to a certain extent for poaching losses.”
Ferreira et al. (2015) further elaborated on density-dependent regulation of populations by stating that “theoretical models predict increased juvenile mortality, followed by fecundity reduction and ultimately increased adult mortality when large herbivores experience density-dependent regulation.” However, it is also pointed out that these vital rates were not affected in the Hluhluwe/Imfolozi Reserve with a higher density of rhino and over a longer period than the Kruger Park.

Yet, Dr Ferreira relies on the theoretical models, in spite of some acknowledged shortcomings, in explaining white rhino population trends in the Kruger Park!Glib generalised clichés such as “density dependent ecological processes” (or “natural regulation is taking place” and “a classic population response” as in the case of elephants) without substantiated research results are just not good enough. Dr Ferreira needs to provide the research results to give credenceto his assertion that the rhino population had stabilized in 12 landscapes and that the theoretical processes are valid and applicable to the Kruger Park rhino.

The trend of the rhino population for the period 2008 to 2017, together with those poached, is presented in Table 1. However, it is not really possible to assess the impact of poaching on the population as no indication of sex or age ratios or the reproductive status of adult cows (unborn calves, lactating, etc) is given. In addition, neither is any mention made of natural deaths, i.e. from old age, fighting, injuries, etc.
What does seem quite evident, however, is the precipitous fall in the rhino numbers between 2015 and 2017.



Table 1: White rhino census totals and numbers poached in the Kruger National Park for the period 2008 to 2017.

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So what has happened to the rhino
In Tables2 and 3 some idea is presented to indicate the trend the population has followed since 2010. The tables are based on recruitment rates of 6% and 8%, and also make provision for natural attrition of the population at 1% and 3% rates.

Based on these vital rates it is evident that poached animals exceeded recruitment from 2013, at the time that SANParks were predicting the “tipping point” in 2016.
Even with the tipping point being reached in 2013 Tables 2 and 3 indicate expected populations of over 8 000 for 2015 and 2016 at both 6% and 8% recruitment rates and over 6 000 for 2017. Official figures (Table 1) are 8 875 for 2015, approximately 7 000 for 2016 and 5 000 for 2017, losses of 21% between 2015 and 2016 and 28% between 2016 and 2017 (44% between 2015 and 2017). These losses are huge and well in excess of the annual recruitment rates.

The following may all have played a role to account for these losses:

1. Drought-related deaths

White rhino are short-grass grazers and the intensity of the 2016/17 drought may have been severe enough to have caused deaths, both of young born during this time and handicapped adults. Such deaths have been compensated for at 1% and 3% levels in Tables 2 and 3 (see below). To what extent recruitment was affected is arguable and could have been even less than 6%.
Strangely, in the census tables presented by Joubert (2015) no negative effects are reflected in the rhino population due to the 1991/92 drought, which was closely comparable to that of 2016/17 though not as intense in some respects.
It may be accepted that drought played some role in the decline of the population but certainly not at the rate indicated by the official census figures.

2. Census

Since the inception of the Park it has been accepted that a knowledge of the numerical strengths of the various animal populations is an essential ingredient in considering management strategies. Several attempts at establishing population totals were, therefore, employed and the first recorded list of totals was published in 1918, by the Game Reserves Commission chaired by Adv Joe Ludorf. Though not much more than guesstimates it at least provided some idea of relative abundances.

Road strip and differential counts followed but it was not until the implementation of the annual helicopter census of elephants and buffalo in the mid-1960’s and the Ecological Aerial Surveys (EAS, mid-1970’s) that satisfactory results were obtained for all the larger herbivore species. The data sets of these censuses are well documented and represent an invaluable asset for the Park.

The EAS were discontinued early in circa 2000 and replaced by Line Transect Counts. These initially covered 6% of the Park but when this proved unsatisfactory the area was incrementally enlarged to 22% before it was discarded.

In circa 2007/8 Prof Rudi van Aarde and Dr Sam Ferreira advocated that herbivores could not be censused without bias in large conservation areas. This was supported by Dr David Mabunda, then CEO of SANParks. Dr Mabunda informed me that censuses would be called off.
This attitude was challenged and on two occasions I have seriously urged SANParks to institute thorough censuses.

• This was in 2010: “I have on occasion written to Dr Mabunda and suggested that it is time for a proper census to be done of all the large herbivores of the Park, to the same standards as those done earlier and I feel the need to repeat this suggestion again, as a matter of urgency.” (Joubert, Oct 2010; elephant document),

• and again in 2014: “Recently the Buffet Foundation, of the USA, announced a grant of some R253 million for SANParks to assist in their anti-poaching operations. To narrow the large range of CI limits for the (rhino) population at the 95% level and to gain a more accurate assessment of the population it is contended that, at this stage, valuable return for their money would be about R1 million (0.4% of the donation) to sponsor a comprehensive census of the rhino and elephant populations of the Kruger Park. This census should include all the methods previously applied, take place simultaneously and include not only Kruger Park but also independent teams to conduct the surveys.” (Joubert, Oct 2014; rhino document).

I have no idea how attitudes or approaches developed over the following few years but by 2012 it became apparent that censuses of at least elephant, buffalo and rhino, and probably most other large herbivores, were resumed. However, what is seriously concerning is the apparent absence of a census report shortly after each census and/or the moratorium placed on the release of the census results before being approved by the Department of Environmental Affairs. This latter process clearly takes a very considerable time, a situation that can only lead to confusion and serious suspicion that either the DEA or SANParks are not being honest with the results.

For a number of years the impression gained was that the rhino population figures were artificially boosted while the elephant population figures were suppressed, both approaches possibly to appease the public (who were expressing concern about the effect of poaching on rhino, on the one hand, and the rapidly increasing elephant population, on the other).Can this possibly be true?

Another source of concern is the method adopted for the census of rhino (elephants and other game?). This involves block counts and statistical analysis, yielding confidence limits that are so wide apart that the population could either be crashing or flourishing. And providing enough opportunity to hoodwink critics.

Standardised, attempted total counts have been applied and have stood the test of time. Possibly not perfect, but reliable and suitable for determining population trends of all the larger herbivores at practical and workable scale.And free of statistical manoeuvring.
The role of an inadequate census method in determining the population trends of rhino should be seriously considered.
Has a rhino census been conducted this year (2018) and, if so, what is the result?
Removals, translocations

The DEA and SANParks have informed the public that rhino will be relocated to places of safety but it is not certain whether the numbers are made public. Whether the numbers are significant enough to be reflected in the sharp decrease of the rhino population is probably doubtful. Since 1990 1 402 rhino were removed from the Park and a further 217 from north of the Sabie River during 2015/16. If these are all the rhino removed they could not have made much difference to the sharp decline.

3. Poaching

Ferreira et al. (2018) have stated that a large percentage of poached rhino carcasses are found within three days, that up to 88% are located within two weeks but that there was a possibility that an unknown number are not found. Even if this vague possibility does exist it, together with the known deaths, could hardly have contributed much to the calamitous decline in the rhino numbers.

4. Other factors

Ferreira et al. (2018) note the following as possible causes for the steep drop in numbers:

i. Calf survival decreases: white rhino may be sensitive to droughts as they are short-grass grazers and calf percentages may surely have dropped. These factors could have caused a decline. During a similar drought in 1991/92, population increases were recorded (see 1, above).

ii. Movement out of the KNP to the adjoining private nature reserves: such a possibility was considered due to the fact that several waterholes were closed in the Park, as opposed to the retention of waterholes in the private reserves. Another possibility, yes, but probably not much more than that. Sabie-Sands is the only private nature reserve that adjoins the Park where there are reasonable, but low-density, numbers of white rhino. Rhino numbers are low density in the areas adjoining the Associated Private Nature Reserves. Movements of this nature could not have made a significant difference.

iii. Clumping: clumping due to restricted favourable resources during the drought could reasonably have affected the results of a census based on block-counts. To what extent is uncertain – but another reason for discontinuing a census method reliant on statistical manipulation rather than total counts.

iv. Not finding poached carcasses: see (4) above.

CONCLUSION

Two major concerns exist in terms of interpreting the decline in the rhino population, i.e. the reliability (accuracy and precision) of the census data and accuracy of the numbers of rhino poached. All other possibilities alluded to are peripheral and probably of insignificant consequence.
To address the two major areas of concern the following is required:

 Census: to interpret any of the other factors that could play a role in the rhino population trend requires census data of the highest standard. The importance of a clear understanding of the rhino population dictates that no cost or effort should be spared to rule out any uncertainties.
This can only be achieved by means of a census based on an intensive, (attempted) total count and the elimination of any reliance on statistical manipulations.

 More intensive patrols, both aerial and ground surveillance.

 More intensive 24-hour entrance gate controls, e.g. by means of sniffer dogs and any other means, to monitor the potential involvement of staff in the poaching operations.

It is time to seriously consider, or reconsider, these issues.

SCJ Joubert
24 October 2018.

Tables 2 & 3:

Table 2: Calculated population trends at 8% recruitment and 1%, 3% and 5% natural deaths

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Notes:
1. Expected population totals in these tables (highlighted) were derived from census totals, where available, and applying 3% natural mortality and 8% recruitment rates.
2. According to these tables the critical “tipping point” was reached during 2013/2014.
3. Previously SANParks predicted 2016 and 2020 to be the critical dates.
4. During a meeting with Drs Freek Venter and Marisa Coetzee in May 2017 the former stated that deaths from poaching now (2016/17) exceeded recruitment.
5. Dr Venter also stated that the rhino population then (May 2017) stood at 6 000 to 6 500.
6. The CI limits for 2017 (4 759 – 5 532) were released by the Department of Environmental Affairs on 21 September 2018
Should these tables in any way represent a fair calculation of the rhino population trend the previous census figures released by SANParks may be regarded as highly suspect.

Table 3: Expected population trends at 6% recruitment with 1% and 3% natural deaths (census totals (A), poaching stats (B) and natural deaths (C1 and C3) as in Table 2)


YEAR A – [B + C1 (1%)] A – [B + C2 (3%)] RECRUITMENT 6% EXPECTED POPULATION
1% natural deaths 3% natural deaths 1% natural deaths 3% natural deaths
2010 10 370 10 161 622 610
2011 10 141 9 936 614 596 10 992 10 771
2012 8 581 8 408 608 504 10 755 10 532
2013 8 278 8 111 497 487 9 189 8 912
2014 7 723 7 492 463 450 8 775 8 598
2015 7 969 7 784 478 467 8 177 7 941
2016 6 512 6 381 391 383 8 447 8 251
2017 4 595 4 502 276 270 6 903 6 764
2018 4 871 4 772

Documents consulted:

Ferreira, Sam. 2013. An update on rhino research and surveys in SANParks. SANParks: unpublished report.
Ferreira, SM, Cathy Greaver, Grant A Knight, Izak PJ Smit, Danie Pienaar. 2015. Disruption of rhino demography by poachers may lead to population declines in Kruger National Park, South Africa. PLOS/one, June 29, 2015.
Sam M Ferreira, Charlene Bissett, Carly L Cowell, Angela Gaylard, Cathy Greaver, Jessica Hayes, Markus Hofmeyr, Lizette Moolman-van der Vyver, David Zimmermann. 2018. The status of rhinoceroses in South African National Parks. KOEDOE – African Protected Area Conservation andScience. ISSN: (Online) 2071-0771; (Print) 0075-6458.
Sam M Ferreira, Cathy Greaver, ZoliswaNhleko, Chenay Simms. 2018. Realization of poaching on rhinoceroses in Kruger National Park, South Africa. African Journal of Wildlife Research 48 (1): 013001 (2018).
Joubert, SCJ. Oct 2010. Some comments on the management of elephants and related management issues in the Kruger National Park. Unpublished document.

Joubert, SCJ. Oct 2014. Kruger National Park: notes on the advent of commercial poaching. Unpublished document.

WHERE HAVE ALL THE RHINOS GONE.docx

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[Richprins]

Notice the questionable impact of drought...

[Alf]

In just 7 years the population of rhinos dropped by 50%

[Lisbeth]

T R O O P - journey into the rhino horn war



Sad day today for us.

We always come to this part of Kruger as it’s between two middens... and we’ve been lucky a few times in spotting a rhino coming down to maintain his “toilet” by marking in one of them. Today, one midden is gone and the other one is a pile of old grey decaying grass.

On our dvd signing tours in the park, many tourists have been asking us where the rhinos are, as they are no longer seeing them. These observations fuel speculation that we have a really low number of rhinos in the park.

We do need to know the census results of the last count done on our living rhinos in Kruger 10-months ago, especially with CITES around the corner. Rhino management will be handled at CITES in August and it’s vital that Kruger’s population is taken into consideration when deciding rhino management issues for the next three-years.

Worth noting that we have requested the census results for some time now as DEA (the Department of Environmental Affairs) usually releases them in their January update, but nothing then or since then.

[Richprins]

Why do they hide it??

[Alf]

They always wants to hide the truth