Daily Occurrence of African Game Animals at Water Water Holes During Dry Weather

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1 Zoologica Africana ISSN: (Print) (Online) Journal homepage: Daily Occurrence of African Game Animals at Water Water Holes During Dry Weather J. Weir & E. Davison To cite this article: J. Weir & E. Davison (1965) Daily Occurrence of African Game Animals at Water Water Holes During Dry Weather, Zoologica Africana, 1:2, , DOI: / To link to this article: Published online: 02 Oct Submit your article to this journal Article views: 210 View related articles Citing articles: 18 View citing articles Full Terms & Conditions of access and use can be found at Download by: [ ] Date: 22 November 2017, At: 05:13

2 DAILY OCCURRENCE OF AFRICAN GAME ANIMALS AT WATER WATER HOLES DURING DRY WEATHER 1. WEIR AND E. DAVISON Department ofbiological Science, University College ofrhodesia and Nyasaland and Department of National Parks and Wild Life Management, Causeway, Rhodesia Few quantitative studies have been made of the behaviour or biology of the African game animals, although much has been written about them. The data presented here are derived from 27 observational censuses each lasting 24 hours carried out during 1958, 1959 and 1960 in Wankie National Park, Rhodesia, by members of staff of the Department of National Parks, and involving over 11,000 animals. These censuses are conducted on or near the night of the full moon in late September, October or early November (during the peak of the dry season) when the game animals are concentrated near the few pans or waterholes which still contain water. Most of these pans are supplied with water pumped from boreholes. Contemporary literature abounds in conflicting statements on the daily habits of many of these animals. Information on their diurnal activity and movements is important in strip counts (Dasmann and Mossman 1962a) in studies on predation (Dasmann and Mossman 1962b), and in the general biology of these animals. The animals themselves may take some part in the creation of waterholes (Weir 1962) and it seems probable that the pans play an important part in the social behaviour of the mammal herds which congregate near them in dry weather. While such congregations of herds are often reported (Grzimek and Grzimek 1960, Shortridge 1934, Vesey-FitzGerald 1960 and many others), the behavioural and ecological consequences of such enforced high density congregations on the herds themselves have not been investigated. It is not known whether there is any competition for water or, ifthere is, which species ofanimals would be involved in such competition. There might also be competition for time and opportunity to drink as distinct from competition for water. CENSUSES OF TEN HERBIVORE SPECIES Since censuses may include different pans from one yearto the next, data are analysed initially on a 24-hour basis irrespective ofthe pans from which they are derived or of the year during which the census was carried out. Data are presented here for the ten most abundant herbivores recorded, and for the four most abundant carnivores (Table I), infonnation on other species being inadequate. Figure I shows graphically the time of arrival at pans of the total number of 11,314 individuals of all ten herbivore species during the period of 24 hours. While there is continuous usage ofthese pans at all hours of day and night, there is also a pronounced peak in numbers from to Figures 2-12 present the equivalent results for individual species. (In the case of wildebeest, the original data are shown in Figure to and a smoothed graph in Figure II.) Zoologica A/ricana 1 (I):

3 354 ZOOLOGICA AFRICANA VOL 1 TABLE I. SPECIES OF ANIMALS DISCUSSED AND NUMBERS COUNTED Numbers Common Name Specific Name censused Figure here Herbivores Buffalo Syncerus caffer Sparrman.. 3,163 2 Eland.. Taurotragus oryx Pallas Elephant Loxodonta africana Blumenbach 4,931 4 Giraffe Giraffa camelopardalis Linn Kudu.. Tragelaphus strepsiceros Pallas R.oan.. Hippotragus equinus Desmarest Sable.. Hippotragus niger Harris Warthog Phacochoerus aethiopicus Pallas Wildebeest Connochaetes taurinus Burchell and 11 Zebra.. Equus burchelli Gray.. 1, Predators Hyaenas {Hyaena brunnea Thunberg 24 Crocuta crocuta Erxleben Leopard Panthera pardus Linn. 9 Lion.. Panthera leo Linn. 29 Total including predators 11,376 FIG. 1 NOON 1"00 FIGURE 1. Time of arrival at waterholes of 11,314 herbivores comprising ten species. The vertical axis shows the number of animals per hour class at all pans.

4 1965 WEIRetal.: GAME OCCURRENCE AT WATER HOLES 355 FIG,2. NOON '400,."" NDNIGHT 0> IlOO NOON FIGURE 2. Buffalo. FIGURE 3. Eland. 3. FIG, 4. NOON FIGURE 4. Elephant NOON FIGURES 2-4. Times of arrival at waterholes of individual species. In each case the vertical axis shows numbers of animals arriving per hour class at all pans, and the horizontal axis shows the hour class.

5 356 ZOOLOGICA AFRICANA VOL 1 NOON 1400 "00 'IDO : W'DNIGHT' <000 0' NOON FIGURE 5. Giraffe. FIGURE 6. Kudu. NOON 'AOO "00 ' WIDN 1" FIGURE 7. Roan antelope NOON FIGURES 5-9. Times of arrival at waterholes of individual species. In each case the vertical axis shows numbers of animals arriving per hour class at all pans, and the horizontal axis shows the hour cjass~

6 1965 WEIR etal.: GAME OCCURRENCE AT WATER HOLES 357 aaoo Irr,UDNGWT 0200 FIGURE 8. Sable antelope. NOON FIGURE 9. Warthog > loiiidn'ght 0200,,", FIG NOON The graphs (Figs. 2-12) show that the animals can be divided into four groups as follows: A Buffalo, zebra and giraffe-evening and night drinkers These species are recorded from pans at all hours of day and night, but they show a pronounced evening peak between and Very few buffalo are recorded between and B Wildebeest and eland-night and morning drinkers These species are recorded from pans throughout the night and much of the day but they show a peak in the morning between and c Kudu, sable, roan and warthog-daytime drinkers These four species are usually recorded at pans during the day and avoid the pan for much ofthe night. This is particularly well marked in the case of warthog. which show a pronounced afternoon peak (between and 17 00), are not recorded at all between and 05 00

7 358 ZOOLOGICA AFRICANA VOL 1 NOON 1400 "00, WIDNICioHT otoo 1000 NOOH FIGURES 10 and 11. Times of arrival at waterholes of wildebeest: Actual (Figure 10) and smoothed curves x+zy+2 (Figure 11). The smoothed curve is derived from the formula, where x, y and z are the 4 values for three consecutive hour classes. The vertical and horizontal axes represent the same measurements as in Figures 1 to 9.

8 1965 WEIRetal.: GAME OCCURRENCE AT WATER HOLES 359 NOON 1400 FIGURE 12. Times ofarrival at waterholes ofzebra. Vertical and horizontal axes as in preceding figures. and then show a period of morning activity at the pan from to 10 00, with decreased activity during the middle of the day (10'00 to 14'00). D Elephant Times ofarrival ofthis species at pans fall into a separate category. While some individuals are recorded at pans at all hours of day and night, there is a pronounced peak in numbers between and BEHAVIOUR OF ELEPHANT AT DIFFERENT PANS Analysis of more extensive census records dealing only with the total number of animals recorded at pans during twenty-four hours shows that certain pans are relatively "unattractive" t'o animals in general and elephant in particular (Weir, unpublished). These pans are distinguishable by their physical properties, and the two time census from pans of this kind are not considered further in this analysis. At four pans (Guvalalla, Tshakawanki, Shabi Shabi and Linkwasha) from which eight time censuses are available, elephantcome to drink at the pan from onwards. These pans are referred to subsequently as "Guvalalla-type" pans. At the remaining six pans (Nyamandhlovu, Dom, Makwa, Kennedy I and Shapi) from which 17 time censuses are available, few elephant are recorded at the pan between and 17 00, but the numbers coining to the pan increase sharply after These pans are referred to subsequently as "typical" pans. For statistical comparison the period from to is divided into seven classes each ofone hour duration. Table 2 shows the numbers ofelephant coining to the two categories of pan during each hour. The single census for the pan Kennedy II cannot be allocated clearly to either group.

9 360 ZOOLOGICA AFRICANA VOL 1 TABLE 2. NUMBERS OF ELEPHANT DRINKING BETWEEN AND Total Hour nos. Total no. in these of 7 classes censuses Hour Classes Numbers of elephant arriving: at "typical" pans at "Guvalalla" pans ,113 8 at bothcategoriesofpan ,937 atall pans censused here ,315 Statistical tests using chi-square can then be listed as follows: 1. If figures for "typical" pans are used as expected values, data from "Guvalalla type" pans are significantly different (P= <0 1 %). 2. If hour classes 2, 3 and 4 are amalgamated and 3. If hour classes 2, 3 and 4 are omitted complett':ly, (in view of the low "typical" figures) they still show a significant difference (P= 1.0 %). 4. Use of Brandt Snedecor contingency methods, with variation of the total number of elephant in each group, still produced a significant result (P=O 1%). Other variations on contingency methods leave the comparison significant near the O' 1 per cent level of probability, and this is the minimum level of significance obtainable by such methods. It seems therefore that there are very clear differences in elephant behaviour at the two categories of pan. While the total numbers of elephant involved do not affect the significance of the test, the average numbers of elephant recorded per pan during this seven-hour period are quite different ("typical" pan = 48 4 elephant, "Guvalalla type" pan ~~ TABLE 3. SIGHTING RECORDS OF ELEPHANT (i.e., the numbers of pans at which elephant were sighted, irrespective of the actual number sighted.) Hour Maximum Hour Classes value "Typical" pans "Guvalalla" Type pans

10 1965 WEIReta/.: GAME OCCURRENCE AT WATER HOLES 361 elephant). Table 3 records the numbers of "sightings" of elephant during each hour. (A "sighting" meanl> thatelephantare recordedata pan duringa particularhourclass, irrespective of the number of elephant recorded at anyone pan). Analysis of these data by the chi-square test, omitting class 2 because of low numbers and using "typical" pans for expected values, shows that the occurrence of I>uch sighting sequences at "Guvallala type" pans is between I per cent and O I per cent probable. Omisl>ion of classes 1-3 reduces the significance of this result (P = 5%-2 %). It appears that differences exist in the frequency of sightings of elephant at this time between these two categories of pan. Thus the high numbers of elephant seen at certain pans may be caused by more frequent arrivals of herds at these pans rather than by the arrival oflarger herds at the pans. The ratio, total number ofelephants per hour class to number of "sightings" per hour class, for these two categories of pan is given in Table 4, and it is obvious that there is a wide range in this calculated value of elephant per sighting per pan. Re-examination of the original data collected by observers at these pans does not clarify the problem ofherd size. Statistically, it appears that the arrival of 30 or more elephant at one pan in one hour may obscure the arrival of individual elephant, not belonging to the herd, which arrive about the same time. It is known that elephant "family groups" meeting each other may fuse to form large herds (Buss 1961), the groups meanwhile retaining their individuality and being rapidly reconstituted when necessary, although the observer cannot differentiate them. Further reliable information on this particular behavioural difference cannot be obtained from the present data. TABLE 4. ELEPHANT PER HOUR CLASS SIGHTING RECORDS PER HOUR CLASS Hours Hour Classes I Elephant per ~ighting ~"typical") 15 0 I Elephant per sighting ("Guvalalla") INFLUENCE OF TOURISTS Censuses are taken at pans at which tourists may be present. This provides a comparison of animal habits at pans where tourists are usually watching game with those where tourists are not present. Park regulations normally require tourists to return to camp at 18 00, so they nave to leave some of the more distant pans by or Certain pans are not open for tourist viewing. The presence of wardens at pans during the census period may also affect the behaviour of the game, but as wardens are usually in hides in trees overlooking the pans or in vehicles at some distance from the pan, they probably cause much less disturbance to game (by noise, conversation, etc.). Behavioural adjustments made by the animals over a

11 362 ZOOLOGICA AFRICANA VOL 1 period of days preceding the census period, during which time they may have become accustomed to the presence of tourists at certain pans until a certain hour each day and learned to avoid the pans during this period, may be detectable. Behavioural adjustment of artimals following shooting is recorded by several writers (Roosevelt and Heller 1914, Shortridge 1934). The numbers of animals drinking at certain pans is compared here during a restricted period of time ( (0) in relation to the presence or absence of tourists. Pans at which tourists are present until about are Makwa, Dom, Nyamandhlovu and Guvalalla. P~ms at which there are no touristsduringthis period are Shapi, Ngweshla, Kennedy I, Tshakawanki and Shabi Shabi. All these pans attract animals in numbers during the dry season, and 11 censuses are available from each group. There are insufficient data on eland, wildebeest and roan, but data on the other herbivores is given in Table 5. Results fall into well defined groups. Elephant, buffalo, and zebra all show significantly higher numbers (P = 0 1 %) at pans without tourists. These animals are all evening or night drinkers, and can presumably adjust to tourist presence by postponing their drinking until touristsleave. Kudu, for which there arefewer data, also appear mostfrequently in the absence TABLE 5. INFLUENCE OF TOURISTS ON ANIMALS DRINKING AT PANS Number of animals which Tourists arrived during hour classes: Chi square Species ofanimals (present = +) probability (absent = -) by chance Elephant +T P = < 1% -T Buffalo.. +T I P=-=<'I% -T Zebra +T II P=< I% -T Kudu +T T Warthog +T T Sable +T T T (-Ngw)

12 1965 WEIReta/.: GAME OCCURRENCE AT WATER HOLES 363 of tourists, and may achieve this by selection of particular pans for drinking, since they are largely daytime drinkers. Sable appear to avoid tourists but detailed examination of data shows that this is due to the inclusion of Ngweshla in the "no tourist" group. Censuses show large concentrations ofsable in the vicinity ofngweshla. A value for the remaining "no tourist" pans is also inserted (Table 5, -T-Ngw.). This shows that no significant results can be derived from the very uneven data. INTERACTION OF EFFECTS OF ELEPHANT POPULAnONS AND TOURIST AVOIDANCE It is possible that at certain pans the behaviour of elephant may be affected by both the above factors. At Nyamandhlovu pan tourist influence is probably maximal as there are two observation platforms near the pan from which tourists command a view ofthe whole area with cars coming and going much of the time. Nyamandhlovu usually has a sufficiently large elephant attendance to justify its inclusion in the group of pans with 200+ elephant. Yet any tendency of elephant to advance their time of drinking at this pan will conflict with their tendency to avoid the presence of tourists at the pan by waiting until after before drinking. In any case this pan is very large by comparison with the others and over-crowding may not occur. TABLE 6. PRESENCE OF TOURISTS IN RELATION TO DRINKING BY ELEPHANTS Pan groupings A. Large populations B. C. Small populations Makwa (+ T) Kennedy I (- T) Dom (+ T) (+ T) = with tourists between 3 and 6 p.m. (- T) = without tourists between 3 and 6 p.m. No. elephants at pans Shapi (- T) Shavishavi (- T) Tshakawanki (- T) Guvalalla (+ T) Nyamandhlovu (+ T) Ngwashla (- T) Linkwasha (- T)

13 364 ZOOLOGICA AFRICANA VOL 1 Table 6 shows the mean numbers of elephant recorded from those pans for which time data are available, including in the calculation ofthe mean data from censuses for which times of arrival are not available. The presence or absence of tourists during the period to is indicated. It is apparent that tourists have no obvious effect on the total numbersof elephantcomingto the pans. Nyamandhlovu and Ngweshla show borderline values ofelephant populations, there being just above 200 elephant per census mean at these pans. As judged by elephant drinking times, both these pans fall into Group C (pans with small elephant populations)--which may be interpreted in the case of Nyamandhlovu as due to the large size of the pan coupled with avoidance of tourists. CENSUSES OF THREE PREDATOR SPECIES As only 62 predators are recorded, the data are inadequate for any detailed analysis. Table 7 shows that lion predominate at the pans during the day ( ' 00), leopard being recorded from just before dusk to just after dawn, while hyaena are more exclusively nocturnal. Peak numbers of these three together are reached between and 04 00, a period which in general is not favoured by other animals except in part by elephant, which are generally exempt from predation. Hour Class Lion. Leopard Hyaena TABLE 7. RECORDS OF THREE PREDATOR SPECIES 8 ~ 8 Ṉ o a; ~ o eo... Times of Arrival g 8 ~ ~ ~ ~ ~ Total DISCUSSION AND CONCLUSIONS Numerous conflicting statements on the daily activity and drinking habits of African game animals can be found in the relevant literature. The works of Stevenson-Hamilton (1929, 1937, 1947), Hubbard (1929), Roo!levelt and Heller (1914), Selous (1893), Shortridge (1934) and Wilhelm (1933) may be mentioned in which have been recorded many observations on the daily activity ofgame animals under varied conditions. It seems certain that in many cases their daily activity and behaviour is modified by locality, by the influence of man, and by seasonal

14 1965 WEIRetal.: GAME OCCURRENCE AT WATER HOLES 365 conditions. The present data deal only with animals in one area, at one time ofthe year, at one period of the month. The results presented above show much behavioural flexibility in the daily activity of the individualanimals, butalso reveal definite peaks in the drinking behaviour ofpopulations ofall species. The ten most abundant herbivores censuses fall into three categories: 1. evening and night drinkers: elephant, buffalo, zebra and giraffe; 2. night and morning drinkers: wildebeest and eland; 3. daytime drinkers: roan, sable, kudu and warthog. It is noteworthy that the three largest (elephant, buffalo and giraffe), the three most numerous (elephant, buffalo and zebra), and the two most aggressive (elephant and buffalo) all fall into group (1), evening and night drinkers. If competition for drinking time, drinking space, or for water itself did occur, one would expect it to occur at this time. Observation suggests strongly that this is the time when maximum hoof and foot erosion occurs near the pan, as dust kicked up by animals often hangs in the air over the pan and surrounding area. There is surprisingly little evidence of any interspecific friction at pans during the evening and night. It appears that elephant, buffalo, zebra and giraffe each show a high degree oftolerance of other species during this period. Elephant may spend many hours at a pan but the other species tend to leave the pan rapidly after drinking. While this may be considered simply as departure from a dangerous locality near which lion are often present, it also serves to prevent any build-up in the numbers of these species at the pan. Often two or three hundred animals can arrive, drink and leave a pan within one hour, individuals remaining at the pan only for about five or ten minutes. There appears to be no connection between the total number of animals drinking on anyone day and the length ofthe perimeter ofthe pan. This is a difficult relationship to measure in view of the seasonal and regional variations in rainfall which affect the water level in different pans. It may be that some species drink at other times because of possible interspecific friction with, for instance, elephant, which spend much longer at the pan than do most species. There is some evidence to suggest that intraspecific competition for water occurs among elephant. On arrival at a pan there is often much trumpeting and apparent squabbling amongst individuals for space to drink. It is probable that the water in the concrete and stone reservoirs into which water for some of these pans is initially pumped may be more attractive to the elephant than the water in the pan itself. The water in these reservoirs is cooler and clearer than pan water. The reservoirs however have a diameter of only ft., in contrast to the ft. diameter ofthe smaller pans. Elephant often form a "wall" round these reservoirs while the pan itself may be virtually unoccupied or used for splashing and for mud baths. Further evidence on possible intraspecific competition comes from the earlier time of arrival at a pan-of elephant in regions where an average of 200 or more elephant are recorded per census. It is tempting to suggest that such pans are inadequate for the water requirements of elephants feeding in the vicinity of the pan. Ifsuch inadequacy does exist it is reflected in the behavioural adjustment of the elephant in coming to a pan early in the afternoon, andcould presumably be measured as the relative percentage of the total elephant population in the area coming to the pan between and 17'00, during a number of census periods.

15 366 ZOOLOGICA AFRICANA VOL 1 As new pumps are constantly being installed at pans in Wankie, it will be interesting to. measure the effect on elephant behaviour ofthe installation of a new pump in an area ofhigh elephant density. The time of arrival of elephant at pans where large numbers of elephant are normally censused may be confused with the effect of tourists on animal behaviour. With the small number of censuses available it is difficult to separate these two effects. Nyamandhlovu pan is the central tourist attraction having two observation platforms, but it is also a very large pan, with two pumped reservoirs. The numbers ofelephant coming to Nyamandhlovu pan are sufficiently high for it to be included in the group ofpans with 200 or more elephant per census. However, the time of arrival of elephant at Nyamandhlovu is not particularly advanced in comparison with pans which have a mean of only 100 elephant per census. It may be that the presence oftourists delays the arrival ofthe elephant, and also be that there is so much available space at this pan that there is no overcrowding even when 200 or more elephant come to the pan. It appears that the time ofarrival ofelephant at a pan is a property ofthe pan itself or of the surrounding area and is not dependent on the particular number ofanimals coming to the pan in anyone evening. This suggests that the animals acquire a behavioural response to any one pan over a period oftime, and that subsequent daily variation in numbers does not affect the behaviour of the animals. Possibly if different pans could be used in rotation for viewing from onwards on successive days, the numbers of animals seen in the late afternoon might be still higher. Elephant appear to be one ofthe critical animals involved in the daily drinking pattern at a pan-largelybecause oftheir size and their numbers. It seems likely that the tendency ofthe elephantto drink from reservoirs may forestall much conflict with other animals. Increasing the number of these concrete and stone reservoirs in areas where elephant were abundant, or altering the size of the reservoirs to allow them to accommodate more elephant, might alter the drinking behaviour of the elephant in these areas. Zebra and buffalo normally drink from the pan itself, and where a large herd ofbuffalo arrives at the pan over a short period oftime, individuals may be shoved well into the centre ofthe pan by later arrivals on the bank. Much urination and defaecation by elephant and buffalo can be observed occurring in or near the pan, but it would be difficult to estimate the relative amount occurring at the pan as opposed to that occurring in the neighbouring bush. It does not appear to affect the palatibility of the water as far as buffalo, zebra and giraffe are concerned, but could conceivably be one of the reasons why elephant drihk largely from the reservoirs. Elephant probably select their source ofdrinking water with relation to the physical properties ofthe water or ofthe pan itself. It is known (Weir, in preparation) that pans of certain structural and hydrological types are avoided by elephant. Theyare well known to dig holes in the sand ofriver beds to reach water. and other species utilise these holes for drinking after the elephant have left (Darling 1960). The present data suggest that much has still to be learned about the behaviour ofelephant in relation to their drinking habits. While data on other animal species as presented here are less adequate, certain interspecific conflicts appear possible. It would be of particular interest to investigate the relationships of buffalo. zebra and giraffe to each other and to elephant, when at pans. It appears that even in a National Park where these animals are relatively

16 1965 WEIRetal.: GAME OCCURRENCE AT WATER HOLES 367 undisturbed by human beings, they may still be influenced ethologically and driven towards nocturnalism by the presence of man as a tourist or observer. Cloudsley-Thompson (1961), has discussed previous work on periodicity and rhythmic activity in animals and Park (1940) has considered in detail the problem of nocturnalism. In view of the numbers of animals drinking at all times of day and during much of the night, it seems unlikely that nocturnalism is imposed on these animals climatically (Klauber 1939) or that blood-sucking insects are of much importance (Clark 1914). The present observations do not support Cloudsley-Thompson's suggestion (1961) that more primitive species may be driven to nocturnajism by competition with more efficient species unless the influence of man is considered solely as that of a more "efficient" species. Competition of various kinds may well be occurring, but use of the broad categories of nocturnal and diurnal is an oversimplification. Only by observation over long periods could some of the possible effects discussed above be definitely proven or disproven, as these animal populations are in general not susceptible to experimentation. The effects of routine changes in the provision of water and in the degree of access to particular pans could prove to be useful substitutes for experiments. SUMMARY Observational censuses at pans in Wankie National Park, Rhodesia, provide quantitative data on the, daily drinking habits of the common herbivores and carnivores. Populations of herbivores fall into three groups: (1) the evening and night drinkers-buffalo, zebra, elephant and giraffe; (2) the night and morning drinkers-wildebeest and eland; (3) the daytime drinkers-warthog, roan, sable and kudu. Individuals of all species except warthog have been recorded from pans at most hours of day and night, and this flexibility of individual behaviour contrasts with the behavioural trends of the species populations recorded above. Warthog are exclusively daytime drinkers. Surprisingly, the commonest, largest and most aggressive species all drink together in the evening. There is some indication that intraspecific competition for water or space to drink could occur among elephant at this time at certain pans where elephant populations are large. Such effects are confused both with that of an apparent avoidance of touri!>ts at certain pans, and of the abundance of certain species in particular areas. The four carnivore species-lion, leopard, and two hyaena!>-are also clearly distinguished in their habits. There remains a wide field of study in the relationships of the herbivore populations both among themselves and with other species when they are forced into close proximity at pans. REFERENCES BUSS, I. o Some observations on the food habits and behaviour ofthe African elephant. J. Wildl. Mgmt., 25 (2): CLARK, A. H Nocturnal Animals. J. Wash. Acad. Sci., 4:

17 368 ZOOLOGICA AFRICANA VOL 1 CLOUDSLEY THOMPSON, J Rhythmic Activity in animal physiology and behaviour. 236 p. Academic Press, New York. DARLING, F. F Wild life in an African territory, a study made for the game and tsetse control Department of Northern Rhodesia. 160 p. Oxford University Press, London. DASMANN, R. F. and MOSSMAN, A. S. 1962a. Road surp counts for estimating numbers of African ungulates. J. Wildl. Mgmt., 26 (I): b. Abundance and population structure ofwild ungulates in some araes ofsouthern Rhodesia. J. Wildl. Mgmt., 26 (3): ~62-268~,. GRZIMEK, M., and GRZIMEK, B. 1~60.census of plains animals in the Serengeti National Park Tanganyika. J. Wildl., Mi;"'t. 24 (I): HUBBARD, W. D. 1929:'Notes on the mammals of Northern Rhodesia and Portuguese East Africa. J. Mammal. Vol. 1(4): KLAUBER:;L. M Studi~s ofreptile life in the arid southwest. Part I. Night collecting on the desert with ecological statistics. Zool. Soc. San Diego, Bull. 114: PARK, O Nocturnalism, the development of a problem. Ecol. Monog., 10: ~OOSEVELT, T. and HELLER, E Life Histories of African Game Animals, 2 vols. J. Murray & Co., London. SELOUS, F. c A hunter's wanderings in Africa. 455 p. R. Bently & Sons, London. SHORTRIDGE, G. c The Mammals of South West Africa, 2 vols. London. STEVENSON-HAMILTON, J The lowveldt, its wildlife and people. 287 p. Cassell & Co. London South African Eden. 311 p. Cassell & Co. Ltd., London Wild life in South Africa. 364 p. Cassell & Co. Ltd., London.. VESEY-FITZGERALD, D. F Grazing succession among East African game animals. J. Mammal., 41 (2): WEIR, J A possible course ofevolution ofpans (animal drinking holes) in Central Africa. Tranf>. Firf>t Fed. Sci. Congo Salif>bury, WILHELM, J. R., Das Wild des Okawangogebietes und des Caprivizipfels. Jour. S. W. Africa Sci. Soc. VI,