Tsavo West Research Articles

Training Kenyan bird ringers

Jackson, J. 2000. Training Kenyan bird ringers. Ostrich 71 (1 & 2): 342. Capturing and ringing birds is a fundamental ornithological field technique, and one that underlies much bird conservation research. In several countries, particularly in Britain and parts of western Europe, ringing is largely an amateur activity. Enthusiasts ring birds in their free time and take part in national surveys, enabling the effective monitoring of bird populations and movements. Until recently ringing in Kenya has been undertaken almost entirely by a handful of expatriate researchers and enthusiasts. Over the last 1CL15 years, it has also been largely confined to one site: Ngulia in Tsavo West National Park. Ringing effort has targeted Palaearctic migrants, mainly ignoring Afrotropical birds. The number of amateur and professional Kenyan ornithologists is fast increasing, but only a handful have any ringing experience. The remainder lack the resources to obtain the necessary equipment or the opportunity to undergo the long training required to become a qualified ringer. In June 1994, the, Nairobi Ringing Group was formed, based at the Department of Ornithology, National Museums of Kenya, Nairobi. The Group provides an opportunity for interested Kenyans to train as amateur ringers to a high standard, using departmental equipment and expertise. Ringing takes place twice weekly at the Nairobi Museum grounds and monthly at a constant effort site in a forest near Nairobi. Excursions have been made to other sites including Lake Magadi, for training in ringing waders, and Ngulia. The Group has a core of seven to ten members and a further 30 have taken part to varying degrees. Over 2 500 birds have been ringed so far and much learned about the identification, ageing and moult of the commoner species.

Two nesting behaviours and life history of a subsocial African dungrolling beetle, Scarabaeus catenatus (Coleoptera: Scarabaeidae)

Nesting behaviour of a large-sized dung beetle, Scarabaeus catenatus (Gerstaecker), was observed at the Tsavo West National Park, south-eastern Kenya. Although this species is taxonomically a member of a dung-roller group (that is, subfamily Scarabaeinae), it had not only a rolling behaviour but also a tunneller behaviour for nesting. In the former case, the scarab rolled a chunk or a ball of dung some distance (0·5–15·5m) away from the dung pat and buried it under the ground. In the latter case, it dug a tunnel near the dung pat (0–1 m) and transported several pieces of dung into the burrow. In both cases, brood nests were completed by a female alone or by male-female co-operation. Four days after dung burial, the female made one to four brood balls out of buried dung, in each of which she deposited an egg. On the other hand, the male left the nest soon after the female completed oviposition. Even after oviposition, the female stayed in the nest and cared for her progeny until they emerged. This indicates that S. catenatus is subsocial. A major source of offspring mortality was likely to be predation by driver ants (Dorylus sp.). Most females seemed to breed one time in each of two or more successive rainy seasons.

The Ostrich Communal Nesting System

As the study of co-operative breeding systems expands, a number of key species form the examples that underpin our general understanding. The ostrich is increasingly becoming such a textbook species, on the basis of the results obtained in Brian Bertram's study of vigilance and egg discrimination in this bird. Here, Bertram presents new data on the ostrich communal nesting system, in which several females lay in one female's nest, with only one female and the male doing all the work. His study unravels the basis of the co-operation observed, and explains how a system involving apparent altruism is maintained by natural selection. It is now possible as never before to explain and quantify the effects of the different choices these birds make and to integrate ecological and morphological factors such as predation and size. Based on three seasons of study in Tsavo West National Park in Kenya, the author recognizes individual birds, detects and monitors well-concealed nests, determines the motherhood of eggs from their surface appearance, and uses time-lapse photography of nests. Key findings are that females can switch rapidly between reproductive strategies, that a nesting female can recognize her own eggs and when necessary discriminate against those of other females, and that the whiteness of ostrich eggs is an adaptation that protects them against overheating but at the cost of greater vulnerability to predation.

Trypanosomiasis and the conservation of black rhinoceros (Diceros bicornis) at the Ngulia Rhino Sanctuary, Tsavo West National Park, Kenya

SummaryTsetse populations and trypanosome infections were monitored at the Ngulia Rhino Sanctuary to assess the impact of trypanosomiasis on rhinoceros. High densities of Glossina pallidipes were found near a permanent spring by the Ngulia escarpment; G. longipennis and G. brevipalpis were also present in lower numbers. Infection rates in G. pallidipes averaged 3·6%, with three times as many T. vivax as T. congolense infections. T. simiae and T. brucei were present at low frequency. DNA probes revealed that all mature T. congolense infections belonged to the Savanna subgroup. G. pallidipes fed on many hosts, with most meals taken from bovids and elephants. Rhino account for one of the blood meals in a small sample taken from G. longipennis. During a time of low tsetse densities (dry season), we estimated that the wild host population was acquiring seven infections per km2 per day. At lower levels of challenge, an experimental rhino became infected with T. congolense. These results are discussed in terms of future plans for the repopulation of rhino in tsetse‐infested areas in Kenya.RésuméOn a surveillé les populations de tsé‐tsé et les infections dues au trypanosome au Ngulia Rhino Sanctuary, pour évaluer l'impact de la trypanosomiase sur les rhinocéros. On a relevé de fortes densités de Glossina pallidipes près d'une source permanente, près de l'escarpement de Ngulia. Il y avait aussi des G. longipennis et des G. brevipalpis mais moins nombreuses. Le taux d'infection des G. pallidipes est de 3, 6 en moyenne, dû trois fois plus áT. vivax qu‘àT. congolense. T. simiae et T. brucei sont peu fréquents. Des tests d'ADN révèlent que toutes les infections déclarées par T. congolense appartiennent au sous‐groupe Savanna. G. pallidipes se nourrit sur de nombreux hôtes, surtout sur les bovidés et les éléphants. Le rhino compte pour un seul repas dans un petit échantillon de G. longipennis. Lors d'une période où la densité de tsé‐tséétait faible (saison sèche), nous avons estirné que la faune sauvage‐hôte sacrifiait sept individus par jour et par km2à l'infection. A des niveaux plus bas d'expérimentation, un rhino “expérimental” a été infecté par T. congolense. On discute de ces résultats dans le cadre de projets de repeuplement par des rhinos, de régions du Kenya infectées par les tsé‐tsé.

Age differences in the timing and biometrics of migrating Marsh Warblers in Kenya

Kelsey, M. G., Backhurst, G. C. & Pearson, D. J. 1989. Age differences in the timing and biometrics of migrating Marsh Warblers in Kenya. Ring. & Migr. 10: 41–47. Marsh Warblers Acrocephalus palustris migrate southwards across East Africa during November and December on a narrow migration front. Night-time trapping of migrants attracted to powerful game-viewing lamps at Ngulia Safari Lodge in Tsavo West National Park in southeast Kenya provides a unique opportunity to study numbers of active migrants in Africa. Marsh Warblers are one of the most numerous species caught. Biometric data spanning twelve years were analysed. The passage of Marsh Warblers became increasingly dominated by first-autumn birds as the season progressed. Differences in weight between individuals appeared to be largely accounted for by differences in fat reserves rather than by wing-length (as a measure of body size). Wing-lengths decreased through the season whereas body weight and fat reserves showed no seasonal change. There was n...

Nesting behaviour of a subsocial African ball‐roller Kheper platynotus (Coleoptera, Scarabaeidae)

ABSTRACT. 1. The nesting behaviour of Kheper platynotus (Bates) was observed in the Tsavo West National Park, east Kenya.2. The construction of the brood ball seemed to be initiated by the female; thereafter, the male joined in. After its construction, the ball was rolled and buried by the male, whilst the female rode on the ball and occasionally helped the male.3. After burying the ball, the male came out on the ground, leaving the female under‐ground. The female coated the ball with soil and her excrement, and let it ferment for about 2 weeks. Thereafter, the female converted the ball into one to four free‐standing brood pears, and laid one egg in each pear. The number of pears produced depended on the size of ball. Even after oviposition, the female remained in the nest to care for the brood.4. Oocytes matured a little before being laid. Excess oocytes were gradually assimilated during brood care.5. Females seemed most likely to breed in two or more successive rainy seasons.6. Although male‐male aggression was observed, size assortative mating was not observed.

Movements and patterns of habitat utilization of elephants in Tsavo National Park, Kenya

SummaryFollowing the 1970‐71 drought, which resulted in heavy elephant mortality, a long‐term study was initiated in Tsavo National Park to determine movements and home ranges of individual elephants and their relations to overall distribution patterns and environmental factors such as rainfall. The preliminary results presented show the post‐drought situation but it is recognized that they may not represent normality. Methods used were radio‐tracking and observations of visually identifiable individuals. Two aerial counts provided data on overall distribution.Two bulls and two cows were radio‐tagged in Tsavo West and two bulls and four cows in Tsavo East, providing home range and movement data. Home ranges in Tsavo West (mean = 350 km2) were considerably smaller than in Tsavo East (mean = 1580 km2).The differences between Tsavo West and Tsavo East are probably related to habitat quality, Tsavo East receiving less rainfall than Tsavo West. This view is supported by the fact that the 1970‐71 mortality was largely confined to Tsavo East.The movements of individuals were useful in interpreting relatively major shifts in elephant distribution that occurred within a 4‐month period.The following preliminary conclusions emerge from the results obtained so far:(1) Elephants in the Tsavo area, particularly Tsavo East, were more mobile during the study period than was assumed from earlier studies, undertaking long‐distance movements in fairly direct response to localized rainfall.(2) A subdivision of the overall population into locally distinct units may exist during the dry season but did not obtain after significant rainfall, when the elephants ranged over wide areas and came into contact with animals from other dry‐season units.(3) Circumstantial evidence suggests that food is the primary proximal factor governing movements and distribution of elephants in the area. Food availability, in turn, is determined largely by the spatial and temporal pattern of rainfall.

THE FEEDING HABITS OF THE YELLOW‐NECKED SPURFOWL (PTERNISTIS LEUCOSCEPU8) IN NORTHERN TANZANIA

SummaryIn late 1984 and throughout 1965 the feeding habits of Pternistis leucoscepus were studied in the north of Tanzania and in the Tsavo West National Park in Kenya.The main food of this bird was found to be the corms of the sedge Cyperus rotundus. Grass and legume seeds and insects formed a small proportion of the diet. P. leucoscepus is not dependent on free water and can occupy waterless country.The species' main habitat is the edge of flood plains with abundant C. rotundus sedge, bounded by shrub and small tree cover.In the two main study areas, Ngase‐rai and Tarangire, the difference in the general density of the habitats is reflected in the occurrence of P. leucoscepus and Francolinus sephaena together in the former area, and of P. leucoscepus, P. cranchii, F. sephaena and F. hildebrandti in the latter. The sympat‐ric occurrence of these related game birds and the apparent similarity of the two spurfowls' feeding habits presents a fascinating ecological problem for further study.