[I haven't designed album covers before... but I was happy with how some of my manatee photos from Vincennes turned out!]
Trends in European zoo collections in the 21st century
- Thread starter lintworm
- Start date
[I haven't designed album covers before... but I was happy with how some of my manatee photos from Vincennes turned out!]
Tree fungus is a nice name for red pandas but I go with little red menace or the Elmo of the zoo world.
You look happy in Thylo's photo, TLD
[I apologise for this eyesore]
Number of zoos kept (current and former during the holding period):
A 1 zoo
B 2-5 zoos
C 6-10 zoos
D >10 zoos
Time period kept:
1 < 1 year
2 1-5 years
3 6-10 years
4 11-20 years
5 > 20 years
* Species successfully bred
♱ Dead end (in case of species gained)
↑ Species gaining popularity (in case of species gained)
A 1 zoo
B 2-5 zoos
C 6-10 zoos
D >10 zoos
Time period kept:
1 < 1 year
2 1-5 years
3 6-10 years
4 11-20 years
5 > 20 years
* Species successfully bred
♱ Dead end (in case of species gained)
↑ Species gaining popularity (in case of species gained)
Rhinoceroses - Rhinocerotidae
# Species kept 1-1-2000: 3
# Species kept currently: 3
# Species gained: -
# Species lost: -
Apart from a brief interlude from 1986-1998 when Port Lympne Wild Animal Park held Sumatran rhinoceros (Dicerorhinus sumatrensis), only 3 of the 5 rhino species have been kept in European zoos the past decades. There have however been great changes in rhino husbandry, which means all 3 represented species are now breeding on a sustainable level to such an extent European born rhinos have even been used in reintroduction programs. The most common rhinoceros kept is the southern white rhinoceros (Ceratotherium simum simum), which has been relatively stable in the number of holders. That does however mask the big change in breeding success the past 25 years, this means that instead of an ageing population dominated by wild caught animals, there is now a sustainable captive population with an ever increasing share of captive bred rhinos. Zoo Dvur Kralove kept northern white rhinoceros (ssp. cottoni) until 2015 and sent 2.2 animals to Kenya in 2009, the final 2 females in Dvur died in 2011 and 2015. The 2 females in Kenya are the last remaining individuals of this subspecies. It is genetically extremely similar to northern white rhino, but they are used as major fundraisers in the fight against extinction.
@WhistlingKite24 As in the wild southern white rhino are the most common rhino in captivity too
Species gaining popularity
Black rhinoceros - Diceros bicornis
While still the least kept rhinoceros in Europe, this rhino has become a lot more common in Europe with a net increase of ~75% in number of holders. This species used to rely on breeding by a few institutions which each held sizable numbers like Zoo Dvur Kralove, Chester Zoo and Port Lympne Wild Animal Park. But this century most zoos in a breeding situation have achieved success to the point there is hardly any space left in Europe. This did however mean that multiple European black rhinos have been reintroduced to their native East Africa. Apart from a single female in Zoo Magdeburg (*1992) all individuals of the eastern subspecies (michaeli) in Europe are now captive bred. There is still a single Southern black rhinoceros (ssp. minor) in Zoo Frankfurt. This male was imported with a female from Zimbabwe in 1989. Their offspring has been rewilded and there was talk the animals themselves would also be sent back too. The female died in 2016 and the old male will live out the rest of his days in Frankfurt.
Greater one-horned rhinoceros - Rhinoceros unicornis
This is another rhinoceros which has spread greatly this century, with the number of holders nearly doubling in less than 25 years. Increasingly better breeding results have resulted in a spread, that concentrated in Eastern Europe and France. 7 out of 82 animals in Europe are still wild caught, but this means >90% of Europe’s population is now captive bred.
@Therabu small tanks, like this greater one-horned rhinoceros, are an ever more common sight in Europe this century
Progress
20/22 orders completed
92/106 families completed
502-511 species present in 2000
519-522 species present in 2023
220-229 species gained this century
210-214 species lost this century
OkapiJohn
Well-Known Member
Although rhino husbandry and breeding have improved a lot in the last decades, it is arguable if you can call these populations sustainable. White rhinos underperformed reproduction-wise compared to their wild counterparts. They have a very skewed reproduction, meaning that just 5.4% of the EEP females are responsible for 33% of all births and only 38% of the females have bred at least once. Calf mortality is above 20%, way higher than in the wild. All of these have lead to projections that over 100 years only 63% of the genetic diversity of the current white rhino population will be preserved (it is worth remembering that the target for sustainability is 90%). At least according to Scott et al., (2022) the EEP population is deemed unsustainable. Black rhinos still have high mortality rates (it is the species of the 3 which is harder to maintain in captivity), low breeding success, and skewed reproduction (Edwards et al., 2015). Black rhinos suffer from metabolic problems such as iron overload in captivity, probably related to diet (they are the only full browser of the 3 species, and browsers are harder to keep than grasers). I do not know much about the Indian rhino as I am not aware of any research done about it.Number of zoos kept (current and former during the holding period):
A 1 zoo
B 2-5 zoos
C 6-10 zoos
D >10 zoos
Time period kept:
1 < 1 year
2 1-5 years
3 6-10 years
4 11-20 years
5 > 20 years
* Species successfully bred
♱ Dead end (in case of species gained)
↑ Species gaining popularity (in case of species gained)
Rhinoceroses - Rhinocerotidae
# Species kept 1-1-2000: 3
# Species kept currently: 3
# Species gained: -
# Species lost: -
Apart from a brief interlude from 1986-1998 when Port Lympne Wild Animal Park held Sumatran rhinoceros (Dicerorhinus sumatrensis), only 3 of the 5 rhino species have been kept in European zoos the past decades. There have however been great changes in rhino husbandry, which means all 3 represented species are now breeding on a sustainable level to such an extent European born rhinos have even been used in reintroduction programs. The most common rhinoceros kept is the southern white rhinoceros (Ceratotherium simum simum), which has been relatively stable in the number of holders. That does however mask the big change in breeding success the past 25 years, this means that instead of an ageing population dominated by wild caught animals, there is now a sustainable captive population with an ever increasing share of captive bred rhinos. Zoo Dvur Kralove kept northern white rhinoceros (ssp. cottoni) until 2015 and sent 2.2 animals to Kenya in 2009, the final 2 females in Dvur died in 2011 and 2015. The 2 females in Kenya are the last remaining individuals of this subspecies. It is genetically extremely similar to northern white rhino, but they are used as major fundraisers in the fight against extinction.
@WhistlingKite24 As in the wild southern white rhino are the most common rhino in captivity too
Species gaining popularity
Black rhinoceros - Diceros bicornis
While still the least kept rhinoceros in Europe, this rhino has become a lot more common in Europe with a net increase of ~75% in number of holders. This species used to rely on breeding by a few institutions which each held sizable numbers like Zoo Dvur Kralove, Chester Zoo and Port Lympne Wild Animal Park. But this century most zoos in a breeding situation have achieved success to the point there is hardly any space left in Europe. This did however mean that multiple European black rhinos have been reintroduced to their native East Africa. Apart from a single female in Zoo Magdeburg (*1992) all individuals of the eastern subspecies (michaeli) in Europe are now captive bred. There is still a single Southern black rhinoceros (ssp. minor) in Zoo Frankfurt. This male was imported with a female from Zimbabwe in 1989. Their offspring has been rewilded and there was talk the animals themselves would also be sent back too. The female died in 2016 and the old male will live out the rest of his days in Frankfurt.
Greater one-horned rhinoceros - Rhinoceros unicornis
This is another rhinoceros which has spread greatly this century, with the number of holders nearly doubling in less than 25 years. Increasingly better breeding results have resulted in a spread, that concentrated in Eastern Europe and France. 7 out of 82 animals in Europe are still wild caught, but this means >90% of Europe’s population is now captive bred.
@Therabu small tanks, like this greater one-horned rhinoceros, are an ever more common sight in Europe this century
Progress
20/22 orders completed
92/106 families completed
502-511 species present in 2000
519-522 species present in 2023
220-229 species gained this century
210-214 species lost this century
So assuming that a population is sustainable based on number of holders is very misleading. Just as an example only 52% of white rhino holders have bred their animals. The number of animals of each species has indeed increased, but that does not immediately translate into sustainable genetics and demographics.
If you want to dive into the topic all this literature is very interesting:
Scott, S. E., Cain, B., de Kort, S. R., Johnson, B., Khayale, C., Versteege, L., & Bettridge, C. M. (2022). Group composition impacts reproductive output and population viability in captive white rhinoceros. Animal Conservation, 26(3), 290-302.
Radeke-Auer, K., Clauss, M., Stagegaard, J., Bruins-Van Sonsbeek, L. G., & Lopez, J. (2023). Retrospective pathology review of captive black rhinoceros Diceros bicornis in the EAZA Ex-situ Programme (1995-2022). Journal of Zoo and Aquarium Research, 11(2), 298-310.
Wittwer, A., Roller, M., Müller, D. W., Bertelsen, M. F., Lackey, L. B., Steck, B., ... & Clauss, M. (2023). Historical development of the survivorship of zoo rhinoceroses—A comparative historical analysis. Zoo Biology.
Edwards, K. L., Walker, S. L., Dunham, A. E., Pilgrim, M., Okita-Ouma, B., & Shultz, S. (2015). Low birth rates and reproductive skew limit the viability of Europe’s captive eastern black rhinoceros, Diceros bicornis michaeli. Biodiversity and conservation, 24, 2831-2852.
Pouillevet H, Soetart N, Boucher D, Wedlarski R, Jaillardon L (2020) Inflammatory and oxidative status in European captive black rhinoceroses: A link with Iron Overload Disorder? PLoS ONE 15(8): e0231514.
Just thought I'd check this claim, with the caveat that ZTL and my own knowledge/memories may have gaps or inaccuracies, as it seemed a bit low to me:
There are currently 93 zoological collections keeping Southern White Rhinoceros within the area @lintworm is discussing - this means that I'm omitting the holding at Pafos Zoo in Cyprus along with the Russian, Georgian, Turkish and Israeli holdings on ZTL.
Of these, 38 collections have bred the taxon within the timespan in question - which on the surface would imply a figure of 40.86% breeding success, lower than your own claim.
However, this does not take into account the fact that a significant number of the collections which have not bred the species hold singletons or single-sex groups; as far as I can tell, a total of 23 collections fall into this category - when the breeding figures are adjusted to take this into account the final total is marginally higher than cited, at 54.24%.
So on the surface your claim *is* more or less accurate
although looking at the first breeding dates cited on ZTL I think there's a definite case to be made that the rate of breeding is increasing, and that the figure will correspondingly shift upwards.
OkapiJohn
Well-Known Member
It is not my claim. It is data from Scott et al., 2022.Just thought I'd check this claim, with the caveat that ZTL and my own knowledge/memories may have gaps or inaccuracies, as it seemed a bit low to me:
There are currently 93 zoological collections keeping Southern White Rhinoceros within the area @lintworm is discussing - this means that I'm omitting the holding at Pafos Zoo in Cyprus along with the Russian, Georgian, Turkish and Israeli holdings on ZTL.
Of these, 38 collections have bred the taxon within the timespan in question - which on the surface would imply a figure of 40.86% breeding success, lower than your own claim.
However, this does not take into account the fact that a significant number of the collections which have not bred the species hold singletons or single-sex groups; as far as I can tell, a total of 23 collections fall into this category - when the breeding figures are adjusted to take this into account the final total is marginally higher than cited, at 54.24%.
So on the surface your claim *is* more or less accurate
Not that this has any bearing whatsoever on my remarks
Looking at the paper itself, it is restricted to a four year time period between 2012 and 2016, and as such doesn't take into account any breeding outside this timespan - or indeed the fact that on average the species only breeds every 3-5 years in any case:
These factors probably account for the minor difference in breeding percentages I observed
OkapiJohn
Well-Known Member
this type of study should not take into account data from 20 years ago. because the reality 20 years ago was very different husbandry-wise. So they looked at their most up-to-date data (2012-2016), which best reflects the current practices and with that, they can draw and predict the future of the population. I mean no-one is expecting rhino husbandry to retrogress to what it was in the year 2000 so using data from back then would not make much sense.Not that this has any bearing whatsoever on my remarks
Looking at the paper itself, it is restricted to a four year time period between 2012 and 2016, and as such doesn't take into account any breeding outside this timespan - or indeed the fact that on average the species only breeds every 3-5 years in any case:
These factors probably account for the minor difference in breeding percentages I observed
Thanks for the interesting papers, it is food for thought.
That does paint a bleaker picture then the sounds I had been hearing from the zoo world. That relatively few animals of that time period (1998-2016) have bred is worrying, but it would be more informative to see what percentage of adult animals that are alive now have bred. I would assume that figure is far higher.
While the paper is interesting, I wouldn't put too much trust in their model for the future population trajectory. They acknowledge that the factor that influences the model the most is by far the % of females that calves (see sensitivity analysis), but they seem to have used the % from the period 1998-2016. That isn't a strange choice, but that means it is based on a European rhino population that is different from the one today and tomorrow. Especially 20 years ago there were still many older rhinos from the imports from the 1960s-1980s who never bred. That is just not realistic looking at the rhino population now. I don't know what % of females rhinos has bred which are currently alive, but if I have some spare time I will see what I can dig up. But with 10-18 white rhino births per year in the past years it must be higher and the parameters used are already outdated. That is also something you already see in the table where they compare the time periods 1998-2006 vs. 2007-2016, the trajectory is clearly going in the right direction.
This is based on the studbook analysis until 2010, which is by now 13 years ago. In the meantime quite some things can change. 8 new zoos have bred since then and breeding is now more managed tightly. Given the lack of space (and need for additional holders) it is no surprise the population grows slower compared to the wild and their 5% annual growth target is unrealistic unless 20 new holders are found in the coming 2 decades...
That does paint a bleaker picture then the sounds I had been hearing from the zoo world. That relatively few animals of that time period (1998-2016) have bred is worrying, but it would be more informative to see what percentage of adult animals that are alive now have bred. I would assume that figure is far higher.
While the paper is interesting, I wouldn't put too much trust in their model for the future population trajectory. They acknowledge that the factor that influences the model the most is by far the % of females that calves (see sensitivity analysis), but they seem to have used the % from the period 1998-2016. That isn't a strange choice, but that means it is based on a European rhino population that is different from the one today and tomorrow. Especially 20 years ago there were still many older rhinos from the imports from the 1960s-1980s who never bred. That is just not realistic looking at the rhino population now. I don't know what % of females rhinos has bred which are currently alive, but if I have some spare time I will see what I can dig up. But with 10-18 white rhino births per year in the past years it must be higher and the parameters used are already outdated. That is also something you already see in the table where they compare the time periods 1998-2006 vs. 2007-2016, the trajectory is clearly going in the right direction.
This is based on the studbook analysis until 2010, which is by now 13 years ago. In the meantime quite some things can change. 8 new zoos have bred since then and breeding is now more managed tightly. Given the lack of space (and need for additional holders) it is no surprise the population grows slower compared to the wild and their 5% annual growth target is unrealistic unless 20 new holders are found in the coming 2 decades...
Il gattopardo
Well-Known Member
OkapiJohn
Well-Known Member
Again, you can't look at population sustainability based only on number of animals and holders. Structure and genetic diversity play a big role in effective population size, which is essential for the sustainability of the EEP. 8 years (since 2016) is not that much time for a species that probably has a generation time of 16/17 years. Those models take that into account, so I doubt that anything that different has changed since 2016. It is a slow reproduction and long generation time species. The effects of reproductive underperformance in a such long generation time species will take decades to observe. But I mean if you can produce better evidence than these researchers (EEP coordinator included) and their studbook data, I will be excited to see what you may find!
I mean, that *was* the precise point I just made about the drawback of restricting the study to a time period shorter than the upper end of the average breeding-interval range
had the study covered an extra year or so on either side (in order to encompass this average range) the factor I mentioned wouldn't have been an issue.
OkapiJohn
Well-Known Member
"between 01 January 2012 and 31 December 2016. We chose this timeframe to incorporate current breeding performance at the time of data collection, and to ensure questionnaire respondents were familiar with individual's behaviour and husbandry conditions." They used a 5 years period.I mean, that *was* the precise point I just made about the drawback of restricting the study to a time period shorter than the upper end of the average breeding-interval range
I am well aware who wrote the paper, but the paper and the model base itself on data from 1998-2016, which influences the results negatively. The most important parameter in their model is the % of females calving annually, that is set at 10% in the model. Looking at Figure 1 in the Supplementary Information that 10% mark is surpassed in most recent years, but wasn't met in the earlier years of the study. So that is 1 underestimate based on recent data. Another is calf mortality, which is set at 22%, but in reality is lower in the past years (again dragged down by the earlier research period). The model does however expect a 1:1 sex ratio, but I think there has been a slight male bias over the years in reality, so that would give somewhat lower results. But combine that with the fact that the 10% is based on a number that includes a fair number of individuals that would never have reproduced (even if they still were in their theoretically reproductive years), the parameterization from the model is already somewhat outdated. I understand why they used it, but you can't deny it is a pessimistic world view, even based on their own data.
Another big drawback of such models is that it takes the current situation as the situation for the coming 100 years too. But that is inherently flawed (just like every study that says that all forests will be gone by 2xxx at current deforestation rates), it is the best one can do with such a relatively simple tool, but not realistic. In reality it is much more likely that the zoos with good husbandry will continue to have good success, but the zoos with lesser husbandry will go out of the species. As husbandry is an important indicator of breeding success according to the authors, the numbers should thus improve further in the future, which would likely mean a stabilization at a somewhat smaller population size then now (or at least a much smaller decline). You are correct that genetically that has consequences and there is a skew towards which animals reproduce, but the picture is not as bleak as that simple model suggests.
OkapiJohn
Well-Known Member
"Recent improvements in the proportion of females calving annually (maximum 15% in 2020; Figure S1) are encouraging and, if that trend continues, the population may soon reach the level needed to achieve a self-sustaining population (17%)." They acknowledge the recent improvements that you mentioned. However, we do not know if those improvements will be maintained over the long run (100 years) since due to carrying capacity limitations, reproduction output might be artificially reduced. We do not know if the females responsible for these recent improvements are reaching the end of their reproductive life or not, and if they will contribute again. As they mention only a small proportion of females has been contributing. Furthermore, 8 years is only half a generation for this species and so it is too early to say what will be the impact of the recent improvements. Hopefully, they are a good sign.
You use present data to estimate the future because you do not know the data of the future. No one knows the husbandry of the future. It does not make sense to do estimates thinking "In 10 years we will be doing it better or in this manner". You estimate with the rhino expertise you have today, not with the rhino expertise of the future that you do not have yet. Husbandry improvements might stagnate to a level that might still be insufficient.
All population estimations (Including IUCN assessments) use long periods such as 100 years or X generations. So you are saying that most of what conservation is based upon is not realistic. These models are not used to guess the future, they are used to assess the present reality we have and which impacts it will have in the future. And then give us targets, plans, strategies, directions... The model does not tell us the population will not ever be sustainable, it tells us that looking at the current situation it is not and tells us what we need to do to change that.
Calving females might be the most important factor, however, they point out other issues that I believe will jeopardize the sustainability of the population, mostly the skewed breeding outcome and high calf mortality. This will strongly impact the genetics, and we know what happens to reproduction outcomes when a population becomes highly inbred. It is not bleaking the reality, is identifying the issues and trying to fix them.
However, I am optimistic: the authors point out some important husbandry improvements that will certainly improve reproductive outcomes. I am confident those improvements were implemented in the management of the population even before the publication of the article. If it will be sufficient? We do not know yet, but thanks to the model they have done, now they have a target to pursue.
I just think that your claim that the population was sustainable without looking to any other data than the number of holders and recent breeding output a quite blunt and poorly informed claim.
I am aware sustainability is more then just number of holders and number of births and I have seen news articles from zoos that claim that the white rhino population is now self-sustaining, though those won't have been from the studbook keeper and the numbers do indeed show I was somewhat too optimistic.
That does however not mean that I buy the whole story from the 2022 paper (and especially not your summary in the first post) and I have pointed out as to why I think that the numbers used are too conservative, while acknowledging that I understand why they used those.
As a final example: when looking solely at data from numbers of births (which is the only for which I have a complete dataset, but the SI shows they are closely correlated with the % of females calving) there is a big shift going on. When looking at 10 year intervals these are the numbers:
1997-2006: 6.8 calves per year
2007-2016: 12.7 calves per year
2017-2023: 14.7 calves per year
The data from already 2007 onwards, which is a whole generation time, indicate that the numbers used in the study (based on 1997-2016) are conservative and don't reflect the current reality. The model is indeed a tool to see what they need to improve, but should be taken with a pinch of salt, as all models are only as good as the data provided.
I am quite positive that they are on the right track, but the road is certainly not without challenges