Showing papers by "University of Nairobi published in 1977"

Positional behaviour of olive baboons (Papio anubis) and its relationship to maintenance and social activities

Abstract: A troop of olive baboons (Papio anubis) was studied over a four week period Total observation time was 140 hours, 118 hours of which were spent gathering quantitative data on positional behaviour and the maintenance and social behaviour with which it is associated The contribution of each activity on a time basis to the positional repertoire is described and some data is presented on the development of positional activities in infants The contribution of positional activities to various maintenance and social activities is also described quantitatively The complex of positional, maintenance, social and environmental factors involved especially in feeding, foraging, play, and grooming are described and discussed The similarities between the adaptive response shown during the study period and that of other ground living cercopithecines is also discussed

Fast locomotion of some African ungulates

Abstract: Ten species of ungulate were filmed, galloping in their natural habitat. They ranged in size from Thomson's gazelle (about 20 kg) to giraffe (about 1000 kg). They were pursued to make them run as fast as possible. The films have been analysed to determine speed, stride frequency, stride and step lengths, and duty factors. The dependence of these quantities on body size is discussed. Summary: Fast locomotion of zebra, giraffe, warthog and seven species of Bovidae has been studied. The animals were filmed from a pursuing vehicle while galloping in their natural habitat. Stride frequency was more closely correlated with limb length (represented by hip height) than with body mass. Mean stride frequency was proportional to (hip height)-0·51 and maximum stride frequency to (hip height) -0·63. Maximum speed was between 10 and 14 m s -1 for all species except buffalo (7 m s -1). It was not significantly correlated with body mass. Since the small species ran at least as fast as the large ones they attained higher Froude numbers. Relative stride length was approximately 1·8 (Froude number)0·39 for all species, irrespective of size. Relative step length was approximately 0·65 (Froude number)0·2, both for the fore feet and for the hind ones. The vertical forces exerted by the feet are proportional to (body weight)×(Froude number)0·2 so the forces at maximum speed are larger multiples of body weight for small species than for large ones.

Foraging behaviour of the giant leaf-nosed bat (Hipposideros commersoni)

Abstract: Summary Observations of the giant leaf-nosed bat (Hipposideros commersoni) were made in southern Kenya, East Africa. This bat was present in the study area only in March and early April, at the beginning of the March to May rains, and during the November and December rains. Only females were recorded. Food was large beetles of the families Cerambycidae, Elateridae, Scarabeidae and Chrysomelidae. The bats foraged chiefly in riverine vegetation, where they typically used vantage points some 6 m above the ground in acacia trees. Detection of prey at long range from a vantage point, the selection of large prey, precise assessment of the distance and trajectory of the prey, and interception of prey by brief and direct flights tend to optimize the energy return/ unit of time during foraging. The echolocation signals in relation to foraging style are considered. Resume Les observations sur la chauve-souris Hipposideros commersoni ont ete faites au sud du Kenya en Afrique de I'est. Cette chauve-souris n‘etait presente dans la region surveillee qu'en Mars et le debut d'Avril, au commencement de Mars jusqu'aux pluies de Mai, et durant les pluies de Novembre et de Decembre. Seules les femelles furent enregistrees. Leur nourriture consistait de larges coleopteres membre des familles Cerambycidae, Elateridae, Scarabeidae et Chrysomelidae. I1 a ete observe que les chauves-souris fourrageaient principallement sur la vegetation au long des rivieres ou elles utilisaient des points d'avantage typiquement a 6 m au dessus du terrain, dans des acacias. II est deduit que la detection a longue protee et d'un point d'avantage des proies, l'evaluation precise de la distance et du trajectoire de la proie, autant que I'interception de celle-ci par des vols brefs et directes, tendent a hausser au maximum le gain d'energie par unite de temps pendant le fourrage. Les signaux d'echolocation sont aussi consideres en rapport au style de fourrage.

Mortality of wildlife in Nairobi National Park, during the drought of 1973–1974

Abstract: Summary (1) The mortality of wildlife in Nairobi National Park during the drought period of 1973/74 was monitored by monthly ground counts. (2) Highest mortality rate was recorded for kongoni at 27%, followed by wildebeest at 10% and zebra at 7% of the live populations present in the Park. (3) The dry period was marked by a massive influx into the Park of the three species most affected. Eland also moved in, and sub sequently left the Athi-Kapiti ecosystem entirely, while populations of the other species in the Park remained relatively static. (4) Proportionally the highest mortality was recorded in the driest part of the Park and in the forest. (5) Immature and female animals died earliest, but the overall sex and age ratios reflected those reported for live populations, except that a greater proportion of female wildebeest died than expected. (6) Mortality was suspected to result from poor physical condition and lowered disease resistance caused by malnutrition. This occurred during the latter half of 16 consecutive months of below-average rainfall, which considerably reduced vegetation growth. (7) The results are discussed in relation to those found elsewhere in this ecosystem, and in relation to domestic stock, human development and the future of Nairobi National Park.

Rumen fermentation and food selection in East African sheep, goats, Thomson's gazelle, Grant's gazelle and impala

Abstract: The relationship between the selected food and rumen fermentation was investigated in Thomson's gazelle, Grant's gazelle, impala and Maasai haired sheep and goats. All animals were shot in the same grass-bushland area within 1 week during the dry season.According to rumen contents, sheep were almost exclusively grazers. In goats, Thomson's gazelle and impala, grass accounted for about 70% of all plant parts identified. In Grant's gazelle, browse including Acacia seed constituted 68% of rumen ingesta. The two gazelle species showed a very marked preference for green grass leaves.In sheep and goat rumens, concentrations of NH3-N and volatile fatty acids, and in vitro fermentation rates (262 and 272 μmoles gasNTPD/g D.M./h, respectively) were lowest. In the wild ruminants, concentrations of fermentation end-products were higher and the rate of fermentation significantly (P < 0·05) faster, namely 420 in Thomson's gazelle, 356 in Grant's gazelle and 376 in impala. Rumen pH was not significantly different between species, with mean values ranging between 6·3 and 6·0. Total VFA concentrations ranged between 124 and 178 m-equiv/1 in the rumen and around 25 m-equiv/1 in the abomasum. Acetic acid accounted for about 75% of the total VFAs.It is concluded that there are large differences in the pattern of rumen fermentation between wild and domestic mixed-feeding ruminants which reflect their respective food preferences.

Feeding and drinking habits of the black rhinoceros in Masai Mara Game Reserve

Abstract: Summary Feeding and drinking habits of the black rhinoceros (Diceros bicornis L.) population in Masai Mara Game Reserve, Kenya, were studied from May 1971 to August 1972. A total of 108 rhinoceros were recorded in the study area. Feeding rhinoceros were followed behind their feeding tracks until they stopped feeding (or changed to another activity) and the plants which they selected were identified. A technique was used which provided an indication of the relative importance of certain plants in the diet during May to September 1971 (wet-semi-dry), October 1971 to February 1972 (dry) and February to May 1972 (wet-semi-dry). A total of 240 h were spent actually watching feeding rhinoceros in thirteen distribution areas. During this period rhinoceros were observed eating seventy plant species from thirty botanical families. In all distribution areas rhinoceros were very selective for herbs and shrubs, and showed a marked preference for Solanum incanum, Dichrostachys cinerea and Acacia species. Rhinoceros were also observed to visit salt licks which contained sodium, magnesium, potassium and calcium. Two feeding peaks, one in morning and the other in the afternoon were recorded. Black rhinoceros drink water mainly at night. They spend most of the night time near the watering places for they were mostly located in the mornings walking to the feeding grounds.

Studies in Mixed Cropping. II. Population Pressures in Maize–Bean Mixtures

Abstract: An experiment at the Kabete Field Station of the University of Nairobi compared maize–bean mixtures with pure stands of the two crops at three plant densities. Although the mixtures gave an apparent yield advantage over pure stands, this could be explained solely by the increased population pressure in the mixtures. The implication of this finding for other published work with cereal–legume mixtures is discussed, and a distinction is drawn between those sites in East Africa where a conclusive yield advantage from mixed cropping has been found and those where any apparent advantage might be explained by the higher population pressure.

Comparison of voluntary food and water consumption and digestion in Kirk's dikdik and suni

Abstract: Summary Voluntary food and water consumption of Kirk's dikdik (Madoqua kirki) and suni (Nesotragus moschatus) was determined under controlled laboratory conditions. Both species consumed large amounts of dried matter (lucerne hay leaves) per day. Dry matter consumption of dikdik accounted for 3.8 ± 0.5% and of suni for 3.5 ± 0.2% of body weight. Dry matter intake in one immature dikdik and one female dikdik during late pregnancy and lactation was considerably higher. Dikdik drank very little water (278 ml/day, equalling 83 ml/kg0.82) which is further proof of their adaptation to arid environment. Suni drank about twice as much (401 ml/day, equalling 155 ml/kg0.82), but individual variation of water con sumption was high. Thus, the forest-dwelling suni seems to be less adapted to de hydration than the dikdik. There was no difference in the digestibility of dry matter and gross energy of lucerne hay leaves for dikdik and suni. The fraction of N-free extracts which consists mainly of soluble carbohydrates was digested very well (84% and 81%, respectively), whereas fibre and cellulose digestibility was poor. Suni digested crude protein, minerals and cellulose significantly better than dikdik.

Oxygen-binding properties of hemoglobins from estivating and active African lungfish.

Abstract: The oxygen-binding characteristics and the multiplicity of the stripped hemoglobiin from active lungfish Protopterus amphibius, are the same as in specimens that have been estivating for about 30 months, showing that alteration in the hemoglobin molecules is not involved in the earlier reported increase in oxygen affinity of whole blood during estivation (Johansen et al., '76). At pH 7.0 and 26 degrees C the hemolysates show a high oxygen affinity (P50 = 3.1 Torr), a Bohr factor (delta log P50/delta pH) of - 0.33, and a cooperativity coefficient (n) of 1.7. Between 15 and 26 degrees C, the apparent heat of oxygenation (delta H) is - 8.6 Kcal-mole-1 at pH 7.0, corresponding with data for other fish. A low sensitivity of oxygen affinity to urea appears to be adaptive to the high urea concentrations in estivating lungfish. The salt sensitivity is, however, similar to human hemoglobin. The hemoglobin consists of two major (electrophoretically anodal) components, which differ slightly in oxygen affinity but are both sensitive to pH and nucleoside triphosphates (NTP). Guanosine triphosphate (GTP), the major erythrocytic organic phosphate, however, depresses the oxygen affinity of the composite and separated hemoglobins more effectively than ATP suggesting that GTP is the primary modulator of oxygen affinity. Comparative measurements reveal only one major hemoglobin component in P. annectens which has a markedly lower oxygen affinity and phosphate sensitivity than P. amphibius hemoglobins and thus seems less pliable to phosphate-mediated variation in oxygen affinity. The data are discussed in relation to the hemoglobin systems of other fish.

Influence of Light and Temperature on Photosynthesis and Transpiration in Some C3 and C4 Vegetable Plants from Kenya

Abstract: Potted vegetable plants of Amaranthus lividus, Gynandropsis gynandra and Crotalaria brevidens were grown outside under normal tropical conditions and rate of photosynthesis and transpiration were determined simultaneously in attached leaves under a range of leaf temperatures and irradiances. Photosynthetic rates were consistently higher in G. gynandra than in A. lividus and C. brevidens. However, in C. brevidens and G. gynandra the leaf resistances were lower and transpiration rates were higher than those in A. lividus. The results on optimum temperature requirements for maximum rates of CO2 fixation, coupled with data on CO2 compensation points and leaf anatomy provided clear evidence that G. gynandra and A. lividus are C4 species, while C. brevidens is a C3 species. The differential effects of light intensity and temperature on stomata and mesophyll resistances in C3 and C4 species are discussed in relation to rates of photosynthesis and transpiration.

Behaviour of Topi in a Shadeless Environment

Abstract: Topi, Damaliscus korrigum, when living on shadeless pasture, adopt resting postures and an orientation relative to the sun which minimize their exposure to radiation. Their timing of feeding, and hourly variations in faecal moisture loss, contribute to water conservation.

Tissue metabolism and enzyme activities in the rodent Heterocephalus glaber, a poor temperature regulator.

Abstract: 1. Tissue oxygen uptake and enzyme activities were investigated in the naked mole rat, Heterocephalus glaber, a mammal notable for its low body temperature and metabolism and poor temperature regulating ability. 2. Q10 for O2 uptake of Heterocephalus crude liver homogenates ranged from 1.91 for the temperature interval 25-30 degrees C to 1.76 within the range 30-38 degrees C, values similar to those reported for typical homoiotherms. 3. Km pyruvate of lactate dehydrogenase in heart muscle had the same temperature dependence in the mole rat and mouse. 4. O2 uptake and cytochrome oxidase activity of skeletal muscle were higher for mole rat than mouse. The reverse was true for heart muscle. Brain and liver O2 uptake showed similar values for both species, while kidney O2 uptake was highest in the mouse. 5. Pyruvate kinase activity in heart and skeletal muscle was higher in mouse than mole rat, suggesting a greater reliance on glycolysis in the former. 6. Na+, K+ -ATPase activity of liver and kidney was 60% higher in mouse than mole rat, while brain was 30% higher in mouse. 7. The results indicate that the effects of temperature on tissue metabolism in the mole rat conform to those in typical homoiotherms. The low body temperature and O2 uptake in the mole rat find no expression in the tissue respiratory capacity.

Toward regional arrangements for regulation of marine pollution: An appraisal of options

Abstract: The unilateral decision by Canada in 1970 to extend its jurisdiction for the control of pollution of the Arctic waters outward to 100 mi was attacked by some people as a violation of international law. In this paper that model of unilateralism, a regulatory regime by a global agency, and a regional approach are analyzed and appraised with some recommendations for an effective arrangement for the control of pollution in the high seas.

Distribution and post-settlement survival in the field by reproductive pairs ofHodotermes mossambicus Hagen (Isoptera, Hodotermitidae)

Abstract: Debris-piles made byHodotermes mossambicus dealates digging-in after a nuptial flight were found in bushed grassland in central Kenya following unseasonal rain. Their density and survival were estimated, and their distribution examined. These are the first records of post-flight settlement density and survival in the field.

Comparison of analysis of stomach contents and faecal samples from zebra

Abstract: Summary Stomach contents and faecal samples from the same individuals were collected and analysed from eighteen plains zebra in Kajiado district, Kenya. They were analysed microscopically using the point frame method (Chamrad & Box, 1964). The composition of the diets is expressed in terms of ‘parts’ (leaves, sheaths, and stems), while ten grass species which featured prominently in the diet are discussed. The results were tested statistically and regressions were drawn for leaf, sheath and stem proportions in stomach contents and faecal samples. The frequency of leaves appearing in the stomach was found to be consistently higher than that of the faeces while the reverse was the case for sheaths and stems. Out of about sixty species of grasses and five of sedges, the ten most important ones in stomach samples were also the most important species in faecal samples, although some appeared in different orders. All species which had a frequency of at least 3% in the stomach contents were identifiable in the faecal samples.

A Quantitative Evaluation of Placentome Development in Zebu Cattle (Bos indicus)

Abstract: Summary Quantitative changes occurring during placentome development were studied in detail in fetuses of local Zebu cattle ranging in age from about 75 to 245 days of gestation. Total placentome cross-sectional area increased continuously throughout gestation, although placentome number remained constant; this was brought about by an increase in mean placentome crosssectional area alone. Mean placentome cross-sectional area in the gravid horn was almost twice as great as that in the non-gravid horn at all stages of gestation. Changes in placentome cross-sectional area were closely related to changes in placentome depth and volume. Zusammenfassung Quantitative Erhebungen zur Plazentomentwicklung beim Zebu (Bos indicus) Die quantitativen Veranderungen der Plazentomentwicklung wurden an Zebu-Foten im Trachtigkeitsalter von 75–245 Tagen studiert. Bei gleichbleibender Anzahl der Plazentome nimmt deren Gesamtquerschnittsflache wahrend der Trachtigkeit standig zu, und zwar als Folge der Zunahme der mittleren Flachengrose der einzelnen Plazentome, die durchweg im trachtigen Horn fast doppelt so gros war wie im nichttrachtigen. Diese Anderungen hangen mit Anderungen der Hohe und des Umfanges der Plazentome eng zusammen. Resume Evaluation quantitative du developpement des placentomes chez le zebu (Bos indicus) Les changements quantitatifs qui se produisent pendant le developpement des placentomes ont eteetudies chez des fœtus de Zebu de race locale âges de 75 a 245 jours de gestation. La surface totale des placentomes en coupe transversale augmente de facon continue pendant toute la gestation, bien que le nombre de placentomes reste constant. Ceci est realise par la seule augmentation de la surface moyenne de section des placentomes. Cette moyenne s'est averEe presque deux fois plus grande dans la corne gravide que dans la corne non gravide a tous les stades de la gestation. Les changements ont ete lie s a ceux du volume des placentomes. Resumen Una evaluacion cuantitativa del desarrollo de los placentomas del cebu (Bos indicus) Los cambios cuantitativos durante el desarrollo de los placentomas se estudiaron en fetos del cebu de aproximadamente 75 a 245 dias de edad. Durante la gestacion, la superficie total de cortes transversos de los placentomas aumenta constantemente, mantenietidose su numero igual; esto se debe solo al aumento de superficie cuyo promedio es casi el doble en el cuerno gravido en comparacion con el otro. Estos cambios estan intimamente relacionados con los cambios de los placentomas en altura y volumen.

Studies of the permanent incisor eruption, and body development, of the Large East African Zebu (Boran): 1. The ages at first appearance of the incisors, lengths of the incisor eruption period, and sources of variation

Abstract: Observations were made of the ages at first appearance of each pair of permanent incisors (‘eruption age’), and the time from first appearance to full eruption of each pair (‘eruption period’), for Large East African Zebu cattle (Boran). For females the eruption ages were found to be 108·5±9·9 weeks, 137·2±12·9, 165·7±15·8, and 200·9±18·2 for incisor pairs one to four respectively; for steers the figures were 104·3±7·9, 130·3±10·6, 154·6±13·2, and 180·9±14·0; and for bulls 103·3±8·6, 127·6±11·2, 151·0±12·9, and 181·2±15·7. Females were significantly different from steers (P < 0.01), but steers not significantly different from bulls, for all four incisor pairs.The distributions of eruption ages for each sex and pair can be considered as Normal for statistical purposes. There is a tendency for eruption to be asymmetrical after the first pair, with the right tooth preceding the left.Correlations of eruption ages between adjacent pairs are of the order of 0·80 for all pairs and sexes; they decrease progressively as pairs intervene to 0·55 for the first and fourth pairs. Partial correlations approach zero when any intermediate pair is held constant. These results indicate that the whole eruption process is highly interdependent.Evaluation of age grouping and estimations from the presence of incisors showed that this technique, although limited on its own, is still the best developmental trait for ageing. A steer with one incisor pair present had a probability of 0·108 of being the same age or older than one with two pairs. The ages of steers with one and two incisor pairs present were 115·7±12·05 and 140·7±14·27 weeks respectively.Heritabilities of eruption age, for the various incisor pairs, varied between 0·91±0·33 and 0·43±0·25 for females, and 0·87±0·37 and 0·11±0·59 for steers.Sources of environmental variation examined were variation between and within years, both of which were of the same order and a very small proportion of the total variation. The maternal environment had a small effect, probably specifically associated with milk consumption, which had a correlation of —0·22 for females and —0·12 for steers (P < 0.01) with the eruption age of the first incisor pair.Eruption periods for females were 5·1±2·8 weeks, 5·7±3·8, 6·8±4·5, and 8·8±5·6 for pairs one to four respectively; for steers 4·6±2·6, 4·9±2·9, 5·6±3·8, 7·2±5·3; and for bulls 4·9±2·2, 4·8±2·7, 5·7±3·8, 6·0±3·3. Females were significantly slower than steers (P < 0·05) for the first three incisor pairs only, while steers did not differ significantly from bulls for any pair.The distribution of eruption periods was positively skewed, and the correlations between pairs ranged between 0·0 and 0·35. Correlations of eruption ages and periods within incisor pairs lay between 0·50 and 0·95.Variation of eruption periods was not significant within years, but was between years, and arose almost entirely from the first two experimental years. The majority of the heritabilities approached zero.Growth rate differences probably accounted for the differences in eruption periods between the four incisor pairs and the three sexes. The cause of asymmetry of eruption was not the source of the variation in eruption times within incisor pairs, the first tooth consistently having a greater eruption time.

Aerial systematic sampling applied to censuses of large mammal populations in Kenya

Abstract: Summary Four systematic sample censuses are described, one of elephants in Tsavo East National Park, and three of kongoni on the Athi-Kapiti Plains. Flight paths in the form of a regular grid with 5-km spacing were used. Distribution maps from each census are shown. A statistical test is described, which revealed the presence in two of the censuses of non-random features in the spatial distribution of the animals, on a scale large enough to interact with the sampling grid. It is recognized that this could lead to an inflated estimate of variance, as compared to that which would be obtained from a stratified random sample, but it is thought unlikely that any effect of this kind would be appreciable in practice.