Straight Tusked Elephant
I had been thinking about writing about this again and George Monbiot spurred me to write this, following another eloquent, passionate but depressing counsel of despair in the guardian yesterday. George argued that hominims had been driving megafauna to extinction possibly for more than a million years, and drew parallels with modern day elephant slaughter in Africa.
I would look at it another way, as I have previously eg here, here and here. Straight-tusked Elephants were the major ecosystem engineer animals in Europe (alongside rhino, hippos and other smaller mammals like Beavers) over a period of several millions years. Ancestors of modern elephants appeared in the middle miocene about 15 million years ago and returned after each cool phase right up until the previous interglacial to this one, the Ipswichian.
This fascinating paper by Gary Haynes lays out what the impact on landscape and ecosystem may have been from such elephantine giants. Massive long distance trails worn smooth by elephant feet, trees pushed over, bark ripped off. Special clay deposits are sought out by modern elephants (creating Bai in the process) and palaeological evidence indicates the giants of the past did the same, and where large number of animals died, created “Beast Solonetz” sites which attracted human hunters, scavengers and artists. Mammoth bone was extensively used to create talismans, artwork and jewellery going back at least 40,000 years and some of it is staggeringly beautiful.
I was wondering how many straight tuskers there might have been in England in the Ipswichian. It’s difficult to be sure but the best estimates for african forest elephant density are 0.5 to 1 ele per km2 and they weight on average just over 2 1/2 tonnes. Straight tuskers grew to 10 tonnes and 4.3m high. Savannah elephants occur at a higher density (having engineered their ecosystem to provide for them) and can occur at up to 6 per km2. on this basis, I would give a conservative estimate of 1 straight tusker per 1km2 for Ipswichian England. That would mean there were about 250,000 straight tuskers in England, assuming the were able to survive across the whole of England, which this map indicates they did.
Distribution map of Palaeoloxodon antiquus finds by DagdaMor (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0-2.5-2.0-1.0 (http://creativecommons.org/licenses/by-sa/3.0)%5D, via Wikimedia Commons
Modern elephants deposit up to 200kg of dung per day, so scaling up, Straight tuskers deposited 500kg per day, perhaps in 15 piles of 35kg. That would explain why the pleistocene was a paradise for dung beetles. As this recent research shows, the pleistocene dung beetles were species of mosaics of forest and open habitats.
I don’t think it’s too fanciful to wonder whether humans evolved into the species we are, because elephants and their like created and maintained the african savannahs, the mammoth steppe and the open mosaic of Ipswichian Europe that were such fertile hunting grounds for our ancestors. So they were our gods; they created the earth and the landscape early humans depended on and created the habitats for the animals and plants which humans used for all their needs.
It may be true (and from my reading of the literature it’s not quite a clear cut as George suggests) that Cro Magnon people extirpated the Straight Tuskers from Europe during the last Ice age. If they did, then it was people who created the dark (foreboding) Holocene Forest some people call the primeval wildwood.
In which case the semi-natural was born in Britain long before the neolithic; and we killed our original gods millennia ago, then forgot about them.
Photo by PePeEfe (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)%5D, via Wikimedia Commons
The Boy Wonder’s paper in PNAS was a bit of a stretch. Perhaps I should call him Decimus? How could anybody accept a paper that misuses the word “decimate”? Ah, but then the editor was Bill Sutherland who has never been able to rationalize the existence of open habitat species in the Holocene with the prevalence of woodland. However, Decimus’s paper now “proves” that the Holocene was wooded, and it was only those nasty hominids who cleared it all away, as they had exterminated all those non-grass eating herbivores of the Pleistocene who, of course, were entirely uninfluenced by some pretty nasty carnivores, who we (they) also knocked on the head.
I guess I’ll continue to watch the Ice Age film series, for want of any better explanation.
influenced by carnivores – yes Mark. Elephants are predated by lions in Africa. Do they stop eating grass and knocking over trees?
Ah, but the lions add a spatial dimension to the outcome of the activities of herbivores, something that is missing from the “naturalistic grazing” cited by Decimus as being a contemporary example of “low-intervention conservation management strategies such as rewilding”.
Interesting. Are there studies on the impacts on vegetation of elephants with/without lions in eg Africa, India?
Of course, by the Holocene both the Elephants and the Cave lions had gone, leaving it to the diminutive (!) Bison, Aurochsen and Wolves to be top herbivores/predators. Difficult to not to conclude their effects on the vegetation must have been very different.
Is Chris Sandom your bête noire, Mark?
Nah – just still reeling from his youthful exuberance in declaring that he was the expert on wilderness when we had a quick meeting after ECCB in Glasgow 2012 on the agenda for WILD10 in 2013.
sounds like there are too many big beasts prowling the re-wilding landscape Mark. Perhaps some hominins will arrive soon….
hopefully more than a big pile of herbivore excrement quietly steaming on the forest floor of environmental egoism
Big predators nowadays are wusses by comparison to STT etc. However, elephants do avoid lions – the spatial distribution thing. Lions take kudu, warthog, Hartebeest, zebra, and buffalo at greater extent than chance encounter, in Addo Elephant National Park (SA) while having few encounters with elephants and no kills, despite there being a population of 300 (1). In general, lions take prey within a weight range of 190–550 kg, the most preferred weight is 350 kg (2). There is though a pride of 30 lions in Chobe National Park, Botswana, that switch to preying on elephants during the dry season, killing one every three days, the age range of the prey being 4-11 years (weaned “teenagers”) (3). One suggestion is that through force of circumstance – the annual migration reducing ungulate prey – that these lions are re-learning the skills of their ancestors! Another answer may be that the elephants have become more sedentary due to the presence of artificial water provisioning.
There’s a problem trying to tie vegetation change with the absence of carnivores in Africa and consequent delimiting of herbivore action. Thus, even though predators like the leopard and lion have disappeared from many of their recent former ranges in the Congo Basin, uncontrolled bushmeat hunting has also reduced herbivore populations (4). However, the loss of three-dimensional (3-D) structure of vegetation in African savannas will lead to the loss of ecological functioning. Based on a range of different age herbivore exclosures in the Kruger National Park (6-, 22-, 35-, and 41-year exclusions) it’s been shown that, as you would expect, areas in which herbivores were excluded over the short term (6 years) contained 38%–80% less bare ground, but with only a few measurable differences in the 3-D structure of woody plants (5). In the longer-term (>22 years), the 3-D structure of woody vegetation differed significantly between excluded and accessible landscapes, with up to 11-fold greater woody canopy cover in the areas without herbivores, and much greater 3-D structural diversity. The authors note these differences affect the diversity and richness of animal species, as well as the ecological functioning of these systems, the greater canopy structural diversity enhances the habitat available for a wide range of organisms BEYOND THE HERBIVORE COMMUNITIES and alters such ecological processes as nutrient cycling, seed dispersal, and germination. The authors suggest that land managers at KNP will have to consider altering or deflecting herbivore populations in an effort to maintain WHOLE SYSTEM BIODIVERSITY.
(1) Hayward et al (2011) Do Lions Panthera leo Actively Select Prey or Do Prey Preferences Simply Reflect Chance Responses via Evolutionary Adaptations to Optimal Foraging? PLOS One 6: e23607
(2) Hayward, MW & Kerly, G.I. (2005) Prey preferences of the lion (Panthera leo). J. Zool. 267: 309-322
(3) R. John Power, R.J & Shem Compion, R.X. (2009) Lion Predation on Elephants in the Savuti, Chobe National Park, Botswana. African Zool. 44: 36-44
See a cool presentation of this – http://prezi.com/gjk1_sebmxsz/copy-of-lion-predation-on-elephants-in-the-savuti-chobe-national-pa/
(4) Henschel, P. (2009) The Status and Conservation of Leopards and Other Large Carnivores in the Congo Basin, and the Potential Role of Reintroduction. In Reintroduction of Top-Order Predators Eds. Matt W. Hayward and Michael J. Somers, Blackwell Publishing Ltd.
Click to access Statusofleopardsandotherlargecarnivoresinthecongobasinandthepotentialroleofreintroduction_bookchapter_phenschel.pdf
(5) Asner, G.P. and others (2009) Large-scale impacts of herbivores on the structural diversity of African savannas, Proceedings of the National Academy of Science 106: 4947–4952
Click to access 4947.full.pdf