Plants eaten by the savannah elephant in the Cape Floristic Region, part 1

One of the remarkable biogeographical features of southern Africa is the incidence, until recently, of up to four species of megaherbivores (elephants, rhinos and hippos) under temperate climates - in vegetation quite different from that usually associated with Africa.

What is particularly surprising is that the largest-bodied of all, the African bush elephant (Loxodonta africana), has survived to this day near the southern tip of the continent (https://en.wikipedia.org/wiki/Knysna_elephants and https://digitalcommons.wayne.edu/elephant/vol2/iss1/6/), at the latitude of Buenos Aires, Los Angeles, Sydney and Casablanca.

The diet of the African bush elephant near its southernmost limit is of interest because the location of the last survivors:

Because the remaining population has dwindled to just one individual (http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0038-23532019000200016), no further data are likely to be collected on the diet of Loxodonta africana at this edge of its habitat.

So now seems a good time to review the various mainly anecdotal/inferential strands of information (e.g. https://journals.co.za/doi/pdf/10.10520/AJA00423203_2578 and Milewski, A. V. (2002) Elephant diet at the edge of the Fynbos Biome, South Africa. Pachyderm 32: 29-38).

The following refers to a combination of:

  • Koen J H (1983) Seed dispersal by the Knysna elephants, South African Forestry Journal 124: 56-58,
  • my own study of 2002, based on the observations of forest guards Wilfred Oraai and Karel Maswati, and
  • Patterson G, The Knysna elephants - observations on diet, with particular focus on the eating of the medicinal mushroom Ganoderma applanatum.

FOLIAGE (and bark*)

Trees of afromontane forest (https://en.wikipedia.org/wiki/Afromontane):

Shrubs of thicket and/or the edges/understorey of afromontane forest:

Herbaceous plants (including lianes and tree-ferns) in afromontane forest/thicket:

Shrubs of fynbos (https://en.wikipedia.org/wiki/Fynbos):

Herbaceous plants of fynbos:

to be continued in https://www.inaturalist.org/journal/milewski/61207-plants-eaten-by-the-savannah-elephant-in-the-cape-floristic-region-part-2#...

Publicado por milewski milewski, 14 de enero de 2022

Comentarios

Most interesting read, may I ask what is your perspective on the topic of elephant population carrying capacity in south africa (ie. what could the theoretical optimal be for the cape floristic region..)?

Publicado por gingko_biloboa1 hace 11 meses (Marca)

@gingko_biloboa1 Hi Michael, Many thanks for your comment and question. I cannot quantify carrying capacity, but I may be able to point out some relevant principles. There is little doubt that L. africana moved extensively from season to season and in response to wildfires, making the carrying capacity of any given vegetation type or small compartment of land rather meaningless. The dwindling and imminent extinction of the population in the Knysna area may be because this population has long been unable to follow the former migratory/nomadic routes. The overall density of the population of L. africana in the Cape Floristic Region, with its vegetation of fynbos, renosterveld, and afromontane forest, was probably as great as that of the miombo ecosystem that covers much of southern-central Africa, and it probably exceeded that of the miombo ecosystem in Angola, a country in which megaherbivores seem to have been remarkably scarce even before European arrival. So there is no reason to believe that L. africana prefers tropical over temperate climates. Loxodonta africana seems to be most abundant on substrates with moderate nutrient-richness, becoming scarcer on both nutrient-rich substrates and nutrient-poor substrates. Fynbos and miombo woodland are both nutrient-poor vegetation types, but the Cape Floristic Region and the miombo ecosystem include patches of nutrient-richer soils. So what I am suggesting is that the population of L. africana in the southwestern Cape of South Africa was overall about on a par with much of Africa. When we think of the natural community of herbivores in the Cape Floristic Region as a whole, we should think of L. africana as not only part of this community but an important part - despite the likelihood that L. africana was transient in any given patch. Confining the 'Knysna elephants' to afromontane forest/fynbos has not worked in the longer term, and no other conservation area in the Cape Floristic Region is extensive and varied enough in its substrates to allow the reintroduction of the species as a fully wild animal. For me one of the most remarkable aspects of the 'Knysna elephants' is that the most massive land mammal on Earth, by virtue of its intelligence and ability to hide from humans, has managed to survive as a wild animal in an area from which Taurotragus oryx (https://en.wikipedia.org/wiki/Common_eland) and all the other mammals larger than Potamochoerus larvatus (https://en.wikipedia.org/wiki/Bushpig) were exterminated many decades ago. This persistence has been despite the fact that the afromontane forest/fynbos habitat of the Knysna area (https://en.wikipedia.org/wiki/Knysna) is unable to support a breeding population of L. africana and because of the exceptional attunement of L. africana to human ways over its entire evolutionary history as a species. Does this answer help?

Publicado por milewski hace 11 meses (Marca)

Thank for the reply. Very detailed explanation

Publicado por gingko_biloboa1 hace 11 meses (Marca)

@yvettevanwijk1941
I have before me a copy of an anonymous report of the Wild Life Protection and Conservation Society of South Africa, Eastern Province Branch, titled "Knysna elephant survey February 1969-January 1970." The main author is ostensibly Bryan Carter, alias Nick Carter.

On page 4: "The diet of the Knysna elephants appears to include all vegetation found in the forest, from grass to trees, with the exception of gums, pines and, oddly enough, yellow wood trees...The yellow-wood is occasionally broken down, en passant, but never to my, or the trackers' knowledge, eaten. The Saffron tree is also unpopular, but I have seen it eaten on odd occasions. Roots, especially those of the ferns, are popular and more so in winter. These are dug up methodically, as a gardener would clear up a patch of potatoes and I have seen an elephant spend hours on a strip of ground the size of a lorry floor. The roots are shaken to dispose of surplus earth, but enough is swallowed to be seen sometimes in the dung. Possibly the most popular tree for food is the Black-wood (Acacia Melanoxylon)...quite thick pieces of wood are frequently eaten from young trees and sometimes the bark is stripped off for consumption...This, to my mind, completely adequate and varied diet has been responsible for the almost total failure of our attempts to bait them with exotic foodstuffs and thus lure them to cleared areas, where they might have been studied with more ease. Oranges were tried without real success, though one or two of the younger animals sampled them occasionally. The older animals just trod on them or pushed them aside when we suspended them from branches on well-used trails. Salt licks, so successful in Kenya, were put out at strategic points, but were sampled with the enthusiasm of an elderly tea-drinker being forced, out of politeness, to taste a new brew. In no case were they ever returned to, once visited. I should imagine that the animals obtain all the salt that they want from the spray encrusted foliage on the cliff edges where they sometimes browse. On a high wind this salt spray drifts a long way inland...The younger animals avoid the gum plantations, the elder group of three spend much time there. As distinct from long established pine plantations amongst whose trees little else grows, the gum stands let in enough light and rain to encourage a fairly generous secondary growth that gives food and cover."

I assume that 'Saffron' referred to above is Elaeodendron croceum (https://www.inaturalist.org/taxa/557692-Elaeodendron-croceum).

Publicado por milewski hace 11 meses (Marca)

Antoni Milewski, could you send me your email address as I have quite a large nunmber of refernces and some personal; data which you should be interested in. This forum is perhaps not the one to use for that?

Publicado por yvettevanwijk1941 hace 11 meses (Marca)

@yvettevanwijk1941 Hi Yvette, I have done so by Message, with many thanks from Antoni.

Publicado por milewski hace 11 meses (Marca)

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