Two red-capped robin-chats Cossypha natalensis imitate antiphonal duet of black-faced rufous warblers Bathmocercus rufus

During my studies of primate behavioral ecology in the Kibale Forest, Uganda, I documented the first cases of red-capped robin-chats Cossypha natalensis imitating an antiphonal duet. In one case two individual robin chats imitated the entire duet of the black-faced rufous warbler Bathmocercus rufus, each giving both the male and female components. In a second case one robin chat gave the male components and another gave that of the female warbler. The lack of temporal separation between the male and female components of the warbler’s antiphonal duet indicates an unusually high level of auditory perception and response time and cognitive ability on the part of redcapped robin-chats.Keywords: auditory perception, response time, cognitive abilitie

Growth rates in the giant rosette plants Dendrosenecio adnivalis and Lobelia wollastonii on the Ruwenzori Mountains, Uganda

Stem lengths of Dendrosenecio adnivalis and Lobelia wollastonii were measured three times over 5.5 years in the Ruwenzori Mountains, Uganda. These are the only growth data for these two species. Both species had highly variable growth rates. Absolute growth rates in D. adnivalis were not related to the number of rosettes, inflorescences or initial height of plants. The D. adnivalis that were shorter at the beginning of the study grew proportionately faster than did taller individuals. Growth rate was positively associated with annual rainfall for D. adnivalis on the Ruwenzori Mountains, D. keniodendron on Mount Kenya, and D. battiscombei on the Aberdare Mountains. Lobelia wollastonii that were taller at the beginning of the study had greater absolute growth rates than did shorter plants. There was no significant relationship between the initial height and proportional increase in height for L. wollastonii. Growth rate and height are unreliable indicators of age for both species. Keywords: Dendrosenecio, Lobelia, growth rates, Ruwenzori Mountain

Udzungwa Red Colobus Piliocolobus gordonorum Matschie 1900

No abstract available

Long-term declines in nutritional quality of tropical leaves

Global change is affecting plant and animal populations and many of the changes are likely subtle and difficult to detect. Based on greenhouse experiments, changes in temperature and rainfall, along with elevated CO2, are expected to impact the nutritional quality of leaves. Here, we show a decline in the quality of tree leaves 15 and 30 years after two previous studies in an undisturbed area of tropical forest in Kibale National Park, Uganda. After 30 years in a sample of multiple individuals of ten tree species, the mature leaves of all but one species increased in fiber concentrations, with a mean increase of 10%; tagged individuals of one species increased 13% in fiber. After 15 years, in eight tree species the fiber of young leaves increased 15%, and protein decreased 6%. Like many folivores, Kibale colobus monkeys select leaves with a high protein-to-fiber ratio, so for these folivores declining leaf quality could have a major impact. Comparisons among African and Asian forests show a strong correlation between colobine biomass and the protein-to-fiber ratio of the mature leaves from common tree species. Although this model, predicts a 31% decline in monkey abundance for Kibale, we have not yet seen these declines

Line transect sampling of primates : can animal-to-observer distance methods work?

An erratum to this article can be found at http://dx.doi.org/10.1007/s10764-010-9469-4Line transect sampling is widely used for estimating abundance of primate populations. Animal-to-observer distances (AODs) are commonly used in analysis, in preference to perpendicular distances from the line. This is in marked contrast with standard practice for other applications of line transect sampling. We formalize the mathematical shortcomings of approaches based on AODs, and show that they are likely to give strongly biased estimates of density. We review papers that claim good performance for the method, and explore this performance through simulations. These confirm strong bias in estimates of density using AODs. We conclude that AOD methods are conceptually flawed, and that they cannot in general provide valid estimates of density.PostprintPeer reviewe