Derek Pomeroy

THE FOREST BIRDS OF KENYA AND UGANDA

ABSTRACT Robust and rapid ways of assessing and monitoring forest biodiversity are increasingly necessary. To this end, we present a classification of forest birds in Kenya and Uganda into three simple categories: forest-specialists (FF species), forest generalists (F species) and forest visitors (f species). FF and F species, but not f species, are dependent on forests. Out of 479 forest birds in the two countries, 214 are FF, 156 F and 109 f species. Forest-dependent birds, and particularly forest specialists, are less widespread than forest visitors. Uganda has 420 forest birds compared to Kenyas 335, and a higher proportion of forest specialists: this reflects differences in forest structure and biogeography, rather than the area of natural forest. Using this classification allows species lists and densities to be interpreted more meaningfully. The number of FF species is an initial measure of a forests relative conservation importance, while the proportion of FF, F and f species and their relative abundance will shift according to changes in forest structure.

Conserving the Birds of Uganda’s Banana-Coffee Arc: Land Sparing and Land Sharing Compared

Reconciling the aims of feeding an ever more demanding human population and conserving biodiversity is a difficult challenge. Here, we explore potential solutions by assessing whether land sparing (farming for high yield, potentially enabling the protection of non-farmland habitat), land sharing (lower yielding farming with more biodiversity within farmland) or a mixed strategy would result in better bird conservation outcomes for a specified level of agricultural production. We surveyed forest and farmland study areas in southern Uganda, measuring the population density of 256 bird species and agricultural yield: food energy and gross income. Parametric non-linear functions relating density to yield were fitted. Species were identified as “winners” (total population size always at least as great with agriculture present as without it) or “losers” (total population sometimes or always reduced with agriculture present) for a range of targets for total agricultural production. For each target we determined whether each species would be predicted to have a higher total population with land sparing, land sharing or with any intermediate level of sparing at an intermediate yield. We found that most species were expected to have their highest total populations with land sparing, particularly loser species and species with small global range sizes. Hence, more species would benefit from high-yield farming if used as part of a strategy to reduce forest loss than from low-yield farming and land sharing, as has been found in Ghana and India in a previous study. We caution against advocacy for high-yield farming alone as a means to deliver land sparing if it is done without strong protection for natural habitats, other ecosystem services and social welfare. Instead, we suggest that conservationists explore how conservation and agricultural policies can be better integrated to deliver land sparing by, for example, combining land-use planning and agronomic support for small farmers.

Crops, trees, and birds: Biodiversity change under agricultural intensification in Uganda's farmed landscapes

Abstract Geografisk Tidsskrift, Danish Journal of Geography 106(2): 115–130, 2006 This paper examines the relationship between the intensity of agricultural land use and the abundance and richness of trees and birds in a humid tropical developing region where natural vegetation is being rapidly converted into farmland under market and population pressures. We analysed survey data on land use, birds and woody plants collected in 14 study sites situated within smallholder cropland and commercial plantations in southern Uganda. Commercial plantations had very few trees and only 10% of the original bird species. Land use intensification in smallholder systems also showed losses in bird abundance and species richness, but not nearly as much as in plantations. In both systems the impact of intensification was much bigger on the specialised and threatened birds compared to the less specialised species. This argues strongly for ‘species-sensitive’ conservation policies combining protected areas with land use regulation in areas undergoing intensification. We also found a much higher loss in bird biodiversity during the first phases of land use intensification (when larger tracts of forest are cleared) than in later phases characterised by clearing of smaller patches of vegetation and improved management of farm trees. This suggests high pay-offs to geographical targeting of conservation efforts in farmed landscapes.

Dispersion and activity patterns of three populations of large termite mounds in Kenya

ABSTRACT Mound-building termites were studied from 1976–1982 at Emali, Selengei and Ruaraka, three sites in semi-arid southern Kenya. The mounds, most of which were built by species of Macrotermes but some by Odontotermes species, contained 2–20 m3 of soil ha−1. Mound dispersion was regular to a significant degree (implying intra-specific competition) at Emali and Selengei, but not at Ruaraka, where instead there was a distinct vertical zonation of species up a valley slope. Mound-building termites show evidence of intra-specific competition in other ways—for example, large mounds are further apart. Inter-specific competition was also apparent at Emali and there is evidence of inter-generic competition at Ruaraka but of inter-generic associations at Selengei. Building activity increased during wetter periods, whilst feeding, as reflected by the extent of earth coverings, was negatively correlated with rainfall, especially for the Macrotermes species. Ventilation shafts are numerous on large, unshaded mounds of M. subhyalinus, confirming the main purpose of the shafts, which may however limit the maximum size of mounds. M. michaelseni, which has no external openings, uses a different system for ventilation. Flighting by Macrotermes alates shows interesting variations between and within species whose full explanation will require further research.

Bird species richness in tropical Africa: Some comparisons

Abstract Species richness provides a simple measure of diversity, and high diversity is commonly considered a desirable attribute of an area. To determine factors favouring high species richness, we obtained data for 18 countries in tropical Africa, and for comparison, 12 in tropical America. We also considered data from smaller areas in Africa. Species richness for African countries depends upon their area, but latitude is even more important. When considering areas of all sizes, separation into moist and dry was found useful. Species richness is similar in both moist and dry areas up to about 10 4 km 2 , but increases much more steeply for larger moist than larger dry areas. Species richness of breeding species is higher for moist than for dry areas of all sizes, and is higher for tropical countries of America than for Africa. Comparison of species totals in particular reserves (or countries) with the predictions given by the lines in the various figures provides a means of assessing their relative values in terms of species richness.

Vulture populations in Uganda: using road survey data to measure both densities and encounter rates within protected and unprotected areas

The cost of field work was generously covered by The Peregrine Fund (USA) and the Royal Society for the Protection of Birds (UK).

Bird atlases – how useful are they for conservation?

In this paper, we argue that bird atlases, and the databases from which they are produced, are becoming increasingly valuable resources – but only in some parts of the world. There is a striking lack of atlases for almost all of the worlds species-rich areas, most notably tropical America and tropical Asia. Yet even comparatively modest data sets (we take Uganda as an example) can be used to create an atlas. Further, their data can yield interesting information with clear value for conservation planning. For instance, we can see that Ugandas main savanna parks are quite well-placed in relation to raptor species richness, whilst other species of conservation concern are less well covered. In contrast, the fine-scale data-rich atlas projects in many American and European countries provide detailed information of great value. Taking examples from England, we show some of their uses in planning both for physical developments and for conservation. Repeating atlas projects after an interval of several years highlights changing distributions and, increasingly, changing levels of abundance. We believe that every encouragement should be given to new (and repeat) atlasing projects - but most especially in the tropics.

Birds to watch: a Red Data List for East Africa

Bennun, L.A., Njoroge, P. & Pomeroy, D. 2000. Birds to watch: a Red Data List for East Africa. Ostrich 71 (1 & 2): 310–314. The value of Red Data books and lists is well established; there has been much recent work on improving the criteria for listing species of conservation concern. So far these have been applied mainly at the global level. Regional lists can be useful, however, in improving the resolution of conservation priorities and setting an agenda for research, monitoring and conservation, especially where data are collected by amateur naturalists. A Red Data list for East African birds has been drawn up following an eight-month process that involved wide consultation within the region, defined as Uganda, Rwanda, Tanzania, Kenya and Burundi. The criteria for listing were based on those defined by IUCN, and summarised in a single, simple table that could be used for screening large numbers of species. A criterion based on geographic range eliminated from consideration vagrant species or those on the extreme edge of their range. A separate Near Threatened category (Lower Risk but very close to Vulnerable) proved useful. An additional category of Regional Responsibility captured species that are entirely or mainly confiied to East Africa, or to three habitats where the region has special responsibility: coastal forests, Albertine Rift forests, and papyrus swamps. A total of 107 species (about 8% of the regional avifauna) were listed as regionally threatened. This includes four Critical, 18 Endangered and 85 Vulnerable species, proportions very close to those expected from the theoretical probabilities of extinction in each case. One hundred and four species were listed as Near-threatened and 153 as Regional Responsibility, 87 of which are not under threat. Placing a species in a particular category of threat, for explicit reasons, poses an hypothesis about its status that can be tested with additional data. This process is now under way with the compilation of a more detailed, annotated list.

Waterbirds of Alkaline Lakes in Western Uganda

ABSTRACT Ugandas only alkaline lakes are found in the Queen Elizabeth Conservation Area and the adjoining Kyambura Wildlife Reserve. Both are Important Bird Areas, a status to which the birds of the lakes contribute. A total of 179 waterbird counts were made between 1984 and 2000, covering eight of the nine alkaline lakes, all of which are small explosion craters. Of the 75 species counted, all but three were non-specialists. Maxima are given for all species, together with seasonal data for five crater lakes. Four lakes regularly supported more than 1,000 Lesser Flamingos each, the maximum being 60,000. They were Maseche, Bagusa, Nshenyi and Munyanyange. Breeding has been attempted, but has been unsuccessful so far. The more important flamingo lakes had high values for conductivity, above 15,000 μS cm−2, whilst species richness is associated with muddy shores and, probably, intermediate levels of alkalinity, between 10 and 50 Meq−1. The lakes are important scenically, for ecotourism, and for the conservation of waterbirds and plants; whilst Lake Katwes traditional production of salt is of considerable economic significance.

A comparison of two survey methods for assessing bird species richness and abundance in tropical farmlands

Capsule Timed species counts could provide a more valuable bird survey tool in the humid tropics than previously suggested. Aims To compare the relative performance of two bird survey methods that differ in complexity – point counts with distance sampling; and timed species counts – for estimating the species richness and abundance of bird species in tropical farmlands. Methods Twenty-six sites were surveyed in banana–coffee farmland habitats north of Lake Victoria, central Uganda. Point counts and timed species counts, each lasting ten minutes, were conducted at ten stations in each site. Results The two methods provided similar estimates of species richness in farmland and a significant positive correlation between measures of frequency of occurrence of bird species from the two methods was found. There was also a significant positive correlation between density from point counts with distance sampling and frequency of occurrence of bird species from the ten-minute counts. Ten-minute counts tended to accumulate bird species faster than point counts but this difference was not significant. Conclusions In these relatively open farmland habitats species richness estimates from both methods were not significantly different. Although density can only be derived from point counts these densities were highly correlated with frequencies from the ten-minute counts. The frequency of occurrence method is much quicker and simpler, in terms of both field methods and analysis, because it does not involve distance estimation. The results presented here suggest that, at least in relatively open habitats, frequency of occurrence provides a valuable index of density of birds.