Diet of the sable antelope, part 3: Hippotragus niger variani, with special mention of geophagy
My reference is:
Richard D Estes and Runhild K Estes (1970) Preliminary report on the giant sable (Hippotragus niger variani). Third progress report. National Geographic Society, hippotragine antelope study.
Pages 5-6:
"There are three main vegetation types [in Luando Nature Reserve, https://www.africatouroperators.org/angola/luando-nature-reserve/], determined primarily by topography and drainage:
- Brachystegia/Julbernardia woodland, on elevations and other well-drained sites. The greater part of the reserve consists of this woodland. Julbernardia paniculata, Brachystegia boehmi, Isoberlinia angolensis, B. spiciformis, and B. floribunda are the dominant trees, while a variety of other pinnately compound species of the Caesalpinioideae are common. Which species dominate varies according to position in the soil catena. For instance, B. floribunda tends to dominate on gravelly and rocky soils in the upper end of the catena, while Isoberlinia angolensis, B. ?longifolia together with three species of Uapaca are commonest in the ecotone between edaphic grassland and woodland. Large termite mounds, many supporting sizeable trees, are prominent features of the woodland.
- Anhara grassland, equivalent to the dambos [https://en.wikipedia.org/wiki/Dambo] of Zambia, caused by seasonal waterlogging, interrupts and interdigitates with the woodland. The dominant grasses are Loudetia spp., though small sedges (especially Kyllinga spp.) are more abundant in many places than are grasses. The anharas are studded with grey conical and umbrella-shaped termite mounds [https://www.inaturalist.org/observations/12410718 and https://www.inaturalist.org/observations/20003543]. These provide slight elevations upon which trees and shrubs are able to gain a footing in an otherwise inhospitable environment.
- Floodplain grassland bordering the Luando, part of the Cuanza [https://en.wikipedia.org/wiki/Cuanza_River] and their major tributaries. Grasses grow taller and more luxuriantly here than on the anharas."
Loudetia:
https://www.inaturalist.org/observations?place_id=any&subview=map&taxon_id=489496&view=species
Kyllinga is now part of Cyperus (https://www.inaturalist.org/observations?place_id=7145&subview=map&taxon_id=52734&view=species).
Pages 11-12:
"The giant sable of the Quimbango region frequented woodland during the rainy season. The main reason for preferring woodland over anhara was lo g-ago deduced by Blaine (1922: 321): 'The undergrowth is light, consisting of little low seedlings of bush a few feet High, and a fi e, soft, sparsely-growing grass, which is the principal food of the sable...The soil is a sand loam enriched with leaf-mould, giving place on the dambos to the usual sun-baked knobbly grey clay, where a hard, coarse grass grows which the sable never seems to eat.' This statement is as true today as it was 50 years ago. The Loudetias which dominate the meadows are all wiry stems and no leaf - making them exceptionally good for thatching but useless for grazing (except in their youth, when sable eat a certain amount). In 72 observations of Herds A and C in which the habitat was specified, it was found, however, on the edge of an anhara or tree grassland 47 times (65 percent). Here again, the main reason is that their favourite grasses grow more luxuriantly here, where the ground stays moister than innthe woodland without becoming waterlogged like the anharas. Thus the giant sable, like its counterparts in Kenya and Rhodesia, may be thought of as being largely an edge species...But during the rains, good grasses also grow luxuriantly on and around the termite mounds which are so abundant throughout the woodland. The way sable move from mound to mound is an outstanding characteristic of their feeding behaviour. Investigations of termite mounds have shown that they possess a higher content of humus, nitrogen, and colloidal matter than the surrounding soil, as well as a higher maximum water retaining capacity (Murray, 1938 in Glover, 1964). Large termitaria also occur in the anharas, forming islands upon which grow many of the same grasses found in the woodland. These too are visited by sable, even when the surroundings are muddy or actually underwater, for they are not reluctant to venture on to such ground in order to reach an objective. Not only did they readily cross anharas during the rains, but Herd A regularly went out onto Congolo and Cibila anharas both to drink and to visit a number of different salt licks (characteristically found at the bases of termite mounds; samples have been collected for chemical analysis). On at least one occasion, the herd spent some time wandering about a flooded area while feeding upon the grasses growing on slight elevations -
Pages 13-14:
"The giant sable prefers the same types and selects many of the same species that members of other sable populations were seen to select, especially in Tanzania's Rungwa Game Reserve, where habitat conditions are very similar...Thus such tufted perennials as Brachiaria, Digitaria, Panicum and Setaria spp. are universal favourites. In short, they prefer the best available pasture grasses; furthermore, they select each species at its tenderest and most nutritious stage of growth. A sable typically bites off the outer 15-30 cm of the plant and seldom croos cllser than 20-30 cm. Larger, coarser grasses such as Tristachya superba and Hyparrhenia spp. are also taken as long as they remain tender, but the lower 50 cm or so of these plants may be left, whereas such feathery grasses as Themeda trainersand Hyparrhenia filipendula may be cropped to 10 cm or less. From superficial examination, it often appeared that a herd had specialised almost entirely on one or two different species for a period of a week or two. But whenever grazed plants were actually collected and compared, it turned out that a number of very similar-looking species had been selected. Usually ten or more species accounted for 90 percent of the plants in the sample; seldom did one species make up more than 25-30 percent of the total. The grazing calendar of the sable is closely tied to the phenology of the grasses...Each grass reaches maturity at a particular time, with the result that there is a regular succession of (apparently) dominant grasses, as one common species after another comes into flower. Thus two Digitaria spp. dominated the woodland in November and December, respectively, succeeded by a Tristachya sp. in February and an Andropogon sp. in March. On the anharas, which lagged behind the woodland pastures for some time, an Eragrostis sp. was the first to flower in November, followed by a different Tristachya sp. and finally by Loudetia spp. beginning the end of January. The last of all to mature were the very tall species such as Pennisetum purpureum and Hyparrhenia spp., of which at least 10 occur. Interestingly enough, they started to grow most vigorously after the rains ceased in mid-March, and appear to be largely confined to well-drained deep soils. They are most abundant along the roadside, where they form a narrow strip on either side, in abandoned fields, where tall Hyparrhenia form almost pure stands, and on termite mounds, especially those in the lower parts of the catena. Lately the sable have been seen to feed heavily in some of the flowering Hyparrhenias, but the very tall and coarse species that grow in the plantations and along the roadside are apparently only palatable in their early stages. Sable are also browsers. Considering the general lack of reliable information about this animal, it is remarkable that two of its favourite browse plants have been faithfully recorded by almost every person who has ever observed and written about it. Thus Statham (1922) reported that...Diplorhynchus condylocarpon...and...Dolichos sp. were of major importance in the sable's diet. Undoubtedly it was the local people who called attention to these plants, just as they pointed them out to us, along with a number of other plants that sable browse. In practically every case, observations have borne out their information, although so far we have not seen [Dolichos] eaten. In the case if Diplorhynchus, we have seen sable browsing this very common small tree in almost every area visited to date, and giant sable have been taking it in quantity since the beginning of the study. A low leguminous shrub, Mucuna stans, was equally heavily browsed by Herd B in November and December. For instance, of 75 plants examined in a place where the herd had been feeding, 45 had been browsed. It was one of the dominant shrubs in this part of the woodland, whereas Diplorhynchus was far commoner in the home range of Herd A, which fed on Mucuna stans only occasionally. It is worth noting that both species, the latter in particular, are abundant in abandoned cultivation. Of the dozen-odd other herbs and woody plants which the sable have been seen to browse in Luando, only three were heavily utilised. Early in the season, two succulent Commelina spp. were taken while in flower. Beginning in January, Julbernardia paniculata, the dominant tree, was browsed with increasing frequency. Lately, herds in both the study area and near Mulundo have been feeding heavily on a Blepharis sp., a herb with blue flowers and spiny bracts; last July sable in Victoria Falls National Park were observed eating the dried heads of B. bainesii. The actual percentage if the sable's diet that is made up of browse is unknown and of course variable. It seems unlikely, though, that browse ever accounts for more than 20 percent of the diet."
Tristachya superba:
https://www.inaturalist.org/taxa/595729-Tristachya-superba
Diplorhynchus condylocarpon:
https://www.inaturalist.org/taxa/340194-Diplorhynchus-condylocarpon
Mucuna stans:
https://www.inaturalist.org/taxa/429810-Mucuna-stans
The following are spp. of Dolichos in the miombo biome:
https://www.inaturalist.org/taxa/139256-Dolichos-trinervatus
https://www.inaturalist.org/taxa/1135470-Dolichos-cardiophyllus
https://www.inaturalist.org/taxa/1279859-Dolichos-gululu
https://www.inaturalist.org/taxa/430527-Dolichos-kilimandscharicus
https://www.inaturalist.org/taxa/1462462-Dolichos-pseudocomplanatus
Julbernardia paniculata:
https://www.inaturalist.org/taxa/468575-Julbernardia-paniculata
