CiteULike: Tag drc

Optimizing sound features for cortical neurons.

RC Decharms — 2006-04-05T08:37:13-00:00

Science, Vol. 280, No. 5368. (29 May 1998), pp. 1439-1443.

The brain's cerebral cortex decomposes visual images into information about oriented edges, direction and velocity information, and color. How does the cortex decompose perceived sounds? A reverse correlation technique demonstrates that neurons in the primary auditory cortex of the awake primate have complex patterns of sound-feature selectivity that indicate sensitivity to stimulus edges in frequency or in time, stimulus transitions in frequency or intensity, and feature conjunctions. This allows the creation of classes of stimuli matched to the processing characteristics of auditory cortical neurons. Stimuli designed for a particular neuron's preferred feature pattern can drive that neuron with higher sustained firing rates than have typically been recorded with simple stimuli. These data suggest that the cortex decomposes an auditory scene into component parts using a feature-processing system reminiscent of that used for the cortical decomposition of visual images.

Critical Time for African Rainforests

Robert Koenig — 2008-06-28T19:49:08-00:00

Science, Vol. 320, No. 5882. (13 June 2008), pp. 1439-1441.

10.1126/science.320.5882.1439

Expansion of Industrial Logging in Central Africa

Nadine Laporte — 2007-06-12T13:32:55-00:00

Science, Vol. 316, No. 5830. (8 June 2007), 1451.

Industrial logging has become the most extensive land use in Central Africa, with more than 600,000 square kilometers (30%) of forest currently under concession. With use of a time series of satellite imagery for the period from 1976 to 2003, we measured 51,916 kilometers of new logging roads. The density of roads across the forested region was 0.03 kilometer per square kilometer, but areas of Gabon and Equatorial Guinea had values over 0.09 kilometer per square kilometer. A new frontier of logging expansion was identified within the Democratic Republic of Congo, which contains 63% of the remaining forest of the region. Tree felling and skid trails increased disturbance in selectively logged areas. 10.1126/science.1141057

Factors influencing the formation of ground nests by eastern lowland gorillas in Kahuzi-Biega National Park: some evolutionary implications of nesting behavior.

J Yamagiwa — 2005-04-12T16:14:01-00:00

J Hum Evol, Vol. 40, No. 2. (February 2001), pp. 99-109.

To analyze the factors influencing nesting by gorillas on the ground, three kinds of data were collected in the Kahuzi-Biega National Park: from a single group for 3 years, from 25 groups during a population census, and from a habituated group before and after two social events. The data on the proportion of ground nests built by the single group for 3 years show no significant differences between rainy and dry seasons. Significant differences were found between some vegetation types: in particular, between bamboo forest and others (primary and secondary forests). However, these differences were not prominent or consistent across age-sex classes of gorillas. By contrast, large differences were found in this proportion between adults and immatures in both primary and secondary forests. The low proportion of ground nests built by immatures indicates their vulnerability. The present study suggests that the proportion was not influenced by group size but strongly influenced by the presence or absence of a leading silverback. Data on a habituated group that lost its leading male and acquired a new male after several months clearly show that females and immatures preferred sleeping in trees in the absence of a protector male. Immatures drastically decreased terrestrial nesting (from 54% to 6%, P< 0.001) and increased it (from 6% to 19%, P> 0.05) less dramatically than females did (from 24% to 60%, P< 0.01) after immigration of the new male. These results suggest that vulnerability of female and immature gorillas to predators, in spite of their large body size. Small body size and considerable sexual dimorphism in early hominids implies their frequent use of tree nests and the importance of the male's role as protector.

Bushmeat hunting in the Congo Basin: an assessment of impacts and options for mitigation

David Wilkie — 2005-08-12T10:54:13-00:00

Biodiversity and Conservation, Vol. 8, No. 7. (July 1999), pp. 927-955.

Hunting of wild animals is an important component of household economies in the Congo Basin. Results from the growing corpus of quantitative studies show that: a) bushmeat remains the primary source of animal protein for the majority of Congo Basin families; b) bushmeat hunting can constitute a significant source of revenue for forest families; c) bushmeat consumption by low density populations living in the forest may be sustainable at present; d) demand for bushmeat by growing numbers of urban consumers has created a substantial market for bushmeat that is resulting in a halo of defaunation around population centres, and may be driving unsustainable levels of hunting, even in relatively isolated regions; and e) large bodied animals with low reproductive rates are most susceptible to over-exploitation compared with more r-selected species that apparently can tolerate relatively intensive hunting (Mangel et al. 1996). As urban populations continue to grow and economies revitalise, unless action is taken to alter the demand for, and the supply of bushmeat, the forests of the Congo Basin will be progressively stripped of certain wildlife species, risking their extirpation or extinction, and the loss of values they confer to local economies. Consequently, it is essential that a) logging companies are encouraged or coerced not to facilitate bushmeat hunting and transportation in their concessions, b) we develop a better understanding of the elasticity of bushmeat demand, c) that pilot bushmeat substitution projects are supported and their impact on demand evaluated, and d) social marketing activities are put in place to attempt to direct consumer preferences for animal protein aw ay from bushmeat species that are particularly susceptible to over-exploitation.

A census of the eastern lowland gorillas Gorilla gorilla graueri in Kahuzi-Biega National Park with reference to mountain gorillas G. g. beringei in the Virunga Region, Zaire

Juichi Yamagiwa — 2005-05-05T21:38:16-00:00

Biological Conservation, Vol. 64, No. 1. (1993), pp. 83-89.

A population census of eastern lowland gorillas Gorilla gorilla graueri was conducted in the original part of Kahuzi-Biega National Park, Zaire. At least 258 gorillas (25 groups and nine solitary males) were estimated by bed counts to have survived within the Park in the 1990 bamboo season. In comparison with results of the previous censuses, conducted between 1978 and 1979, the population showed a slight increase. The percentage of immature individuals in the population indicates that gorillas still maintain a healthy population, but mean group size has decreased markedly. Although gorillas expanded their range in the 11 years between the surveys, they have still tended to concentrate in the central well-protected area of the Park, possibly stimulating frequent transfer of females between groups or from groups to solitary males, resulting in the decrease in group size. Recent social changes recorded from observations of habituated groups tend to support this interpretation. Human disturbance in the bridge zone between highland and lowland forests prevents gorillas from making contact with their neighbours and reduces the possibility of outbreeding within the Park. Reference is made to the more detailed censuses of the mountain gorilla G. g. beringei. More international attention will be needed to increase conservation activity to protect gorillas from the hazards of human disturbances in this area.

Population Dynamics of Wild Bonobos (Pan paniscus) at Wamba

Takeshi Furuichi — 2005-05-24T22:05:04-00:00

International Journal of Primatology, Vol. 19, No. 6. (December 1998), pp. 1029-1043.

Context and Development of Sexual Behavior of Wild Bonobos (Pan paniscus) at Wamba, Zaire

Chie Hashimoto — 2005-05-24T21:56:28-00:00

International Journal of Primatology, Vol. 18, No. 1. (February 1997), pp. 1-21.

Forest Elephant Crisis in the Congo Basin

Stephen Blake — 2007-04-18T15:00:14-00:00

PLoS Biology, Vol. 5, No. 4. (1 April 2007), e111.

Debate over repealing the ivory trade ban dominates conferences of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Resolving this controversy requires accurate estimates of elephant population trends and rates of illegal killing. Most African savannah elephant populations are well known; however, the status of forest elephants, perhaps a distinct species, in the vast Congo Basin is unclear. We assessed population status and incidence of poaching from line-transect and reconnaissance surveys conducted on foot in sites throughout the Congo Basin. Results indicate that the abundance and range of forest elephants are threatened from poaching that is most intense close to roads. The probability of elephant presence increased with distance to roads, whereas that of human signs declined. At all distances from roads, the probability of elephant occurrence was always higher inside, compared to outside, protected areas, whereas that of humans was always lower. Inside protected areas, forest elephant density was correlated with the size of remote forest core, but not with size of protected area. Forest elephants must be prioritised in elephant management planning at the continental scale.

Current status of the bonobo (Pan paniscus) in the proposed Lomako Reserve (Democratic Republic of Congo)

J Dupain — 2005-05-21T22:15:58-00:00

Biological Conservation, Vol. 94, No. 3. (July 2000), pp. 265-272.

The creation of a 3800 km2 forest reserve along the Lomako river (Equateur Province, Democratic Republic of Congo) is considered one of the main actions necessary for the conservation of the bonobo (Pan paniscus). We conducted a one-month qualitative survey in parts of the Lomako forest, in order to determine the presence of bonobos and the nature and degree of human disturbance. Results are based on information obtained by questionnaires at human settlements, direct evidence of human activities and forest visits in search of bonobos. There is still a rather large bonobo population in the south-central part of the Lomako forest, relatively free of hunting. However, the northern population seems to be decimated, except in the most impenetrable forest parts. The threats to the proposed reserve are twofold. First, the indigenous inhabitants of the Lomako forest have started intensifying commercial bushmeat hunting as an alternative to the loss of their agricultural economy. Secondly, an increasing number of commercial hunters are entering the area. In addition to the creation of the Lomako Forest Bonobo Reserve, we consider that support of local agriculture and the presence of researchers are the most important factors for the continued preservation of the local bonobo population by the indigenous inhabitants of the forest.

War and Tropical Forests: Conservation in Areas of Armed Conflict

Steven Price — 2005-06-12T21:52:09-00:00

(01 June 2003)

The threat to primates and other mammals from the bushmeat trade in Africa, and how this threat could be diminished

E Bowen-Jones — 2005-06-12T21:42:48-00:00

Oryx, Vol. 33, No. 3. (July 1999), pp. 233-246.

The threat that the bushmeat trade presents to primates and other taxa was assessed from the literature, including data from markets, village hunting studies and logging concessions in Central and West Africa. In many cases the numbers of both common and protected species of primate being killed throughout the region are thought to be unsustainable. This is also the case for other taxa involved in the bushmeat trade, which crosses geographic, cultural and economic boundaries. A suite of measures must be considered to mitigate the effects of this trade, and these measures will have to recognize the local, regional and national socio-economic importance of the trade if they are to result in long-term conservation success.

Preliminary vocal repertoire and vocal communication of wild bonobos (Pan paniscus) at Lilungu (Democratic Republic of Congo)

M Bermejo — 2005-04-18T14:19:16-00:00

Folia Primatologica, Vol. 70, No. 6. (c 1999), pp. 328-357.

Vocal communication in bonobos, Pan paniscus, has been studied mainly in captive groups. The few studies carried out in the wild are on only specific aspects of their behaviour. The aim of this study is to give a preliminary description of the vocal repertoire and a qualitative account of the contextual use of the vocalizations described. Observations were carried out on three wild communities, with a total of 68 individuals, for 685 h. No artificial feeding was used at any stage of the study. The vocal repertoire is composed of 15 vocal units and 19 sequences. There is great variability both in the sequences and in the vocal units, and the categories are not always completely discrete. The repertoire is compared to that of captive bonobos described by De Waal. Most sequences are used in various contexts, and for each behaviour there is a complete array of sequences and their variation. The behaviour patterns observed and the sequences uttered by the animals in each context are discussed.

Wave-Like Spread of Ebola Zaire

Peter Walsh — 2005-10-25T12:56:11-00:00

PLoS Biology, Vol. 3, No. 11. (25 November 2005)

In the past decade the Zaire strain of Ebola virus (ZEBOV) has emerged repeatedly into human populations in central Africa and caused massive die-offs of gorillas and chimpanzees. We tested the view that emergence events are independent and caused by ZEBOV variants that have been long resident at each locality. Phylogenetic analyses place the earliest known outbreak at Yambuku, Democratic Republic of Congo, very near to the root of the ZEBOV tree, suggesting that viruses causing all other known outbreaks evolved from a Yambuku-like virus after 1976. The tendency for earlier outbreaks to be directly ancestral to later outbreaks suggests that outbreaks are epidemiologically linked and may have occurred at the front of an advancing wave. While the ladder-like phylogenetic structure could also bear the signature of positive selection, our statistical power is too weak to reach a conclusion in this regard. Distances among outbreaks indicate a spread rate of about 50 km per year that remains consistent across spatial scales. Viral evolution is clocklike, and sequences show a high level of small-scale spatial structure. Genetic similarity decays with distance at roughly the same rate at all spatial scales. Our analyses suggest that ZEBOV has recently spread across the region rather than being long persistent at each outbreak locality. Controlling the impact of Ebola on wild apes and human populations may be more feasible than previously recognized.

Primatology: Peaceful primates, violent acts

Carl Gierstorfer — 2007-06-07T09:32:56-00:00

Nature, Vol. 447, No. 7145. (06 June 2007), pp. 635-636.

Bushmeat hunting in the Congo Basin: an assessment of impacts and options for mitigation

David Wilkie — 2008-05-20T21:15:59-00:00

Biodiversity and Conservation, Vol. 8, No. 7. (1 July 1999), pp. 927-955.

Hunting of wild animals is an important component of household economies in the Congo Basin. Results from the growing corpus of quantitative studies show that: a) bushmeat remains the primary source of animal protein for the majority of Congo Basin families; b) bushmeat hunting can constitute a significant source of revenue for forest families; c) bushmeat consumption by low density populations living in the forest may be sustainable at present; d) demand for bushmeat by growing numbers of urban consumers has created a substantial market for bushmeat that is resulting in a halo of defaunation around population centres, and may be driving unsustainable levels of hunting, even in relatively isolated regions; and e) large bodied animals with low reproductive rates are most susceptible to over-exploitation compared with more r-selected species that apparently can tolerate relatively intensive hunting (Mangel et al. 1996). As urban populations continue to grow and economies revitalise, unless action is taken to alter the demand for, and the supply of bushmeat, the forests of the Congo Basin will be progressively stripped of certain wildlife species, risking their extirpation or extinction, and the loss of values they confer to local economies. Consequently, it is essential that a) logging companies are encouraged or coerced not to facilitate bushmeat hunting and transportation in their concessions, b) we develop a better understanding of the elasticity of bushmeat demand, c) that pilot bushmeat substitution projects are supported and their impact on demand evaluated, and d) social marketing activities are put in place to attempt to direct consumer preferences for animal protein away from bushmeat species that are particularly susceptible to over-exploitation.