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Mineral exploration and sustainable developmentMineral exploration and sustainable development : proceedings of the Seventh Biennial SGA Meeting, Athens, Greece, 24-28 August 2003, ISBN:90-77017-77-1

Chimpanzees, like all great ape species, have experienced a dramatic decline in global numbers during the past decades. The degradation, fragmentation and loss of suitable habitat impede chimpanzee movements, reducing the potential for dispersal and thus population viability. In Tanzania, 90% of the 2 000-3 000 remaining chimpanzees are found within the Greater Mahale Ecosystem (GME), the majority of which live at low densities outside of national park boundaries. Recent genetic analyses have identified potential boundaries between the northern and southern populations of the GME. Using landscape connectivity modelling, we aimed to clarify population connectivity across this vast ecosystem (>20 000 km2 ) and assess change over time. We developed habitat suitability models to create an index of habitat selection by chimpanzees and mapped connectivity using circuit theory. Our results suggest that, in recent history (1973), the entire ecosystem was linked by a series of corridors showing a high likelihood of chimpanzee movement. Our analysis also reveals a reduction of connectivity by 2017 impacting the two corridors linking the northern and southern GME. When projected to 2027, areas contributing to connectivity are predicted to continue to decline, threatening all available corridors between the northern and southern GME. By modelling connectivity across time, we were able to identify key areas to focus conservation efforts to maintain population viability within the largest chimpanzee population in Tanzania.

More than 75 percent of Tanzania's chimpanzees live at low densities on land outside national parks. Chimpanzees are one of the key conservation targets in the region and long-term monitoring of these populations is essential for assessing the overall status of ecosystem health and the success of implemented conservation strategies. We aimed to assess change in chimpanzee density within the Masito-Ugalla Ecosystem (MUE) by comparing results of re-walking the same line transects in 2007 and 2014. We further used published remote sensing data derived from Landsat satellites to assess forest cover change within a 5 km buffer of these transects over that same period. We detected no statistically significant decline in chimpanzee density across the surveyed areas of MUE between 2007 and 2014, although the overall mean density of chimpanzees declined from 0.09 individuals/km(2) in 2007 to 0.05 individuals/km(2) in 2014. Whether this change is biologically meaningful cannot be determined due to small sample sizes and large, entirely overlapping error margins. It is therefore possible that the MUE chimpanzee population has been stable over this period and indeed in some areas (Issa Valley, Mkanga, Kamkulu) even showed an increase in chimpanzee density. Variation in chimpanzee habitat preference for ranging or nesting could explain variation in density at some of the survey sites between 2007 and 2014. We also found a relationship between increasing habitat loss and lower mean chimpanzee density. Future surveys will need to ensure a larger sample size, broader geographic effort, and random survey design, to more precisely determine trends in MUE chimpanzee density and population size over time. Am. J. Primatol. © 2015 Wiley Periodicals, Inc.

Chimpanzees are declining at a rate of up to 6.5% per year in some parts of Africa due to human impacts. Effective conservation relies on accurate and reliable information on population density, distribution and connectivity. Yet, traditional line transect surveys are costly to conduct over large areas and particularly at sufficiently regular intervals to determine trends in abundance. Moreover, they often fail to identify critical areas for animal movement. Given the vast landscape across which chimpanzees are found, we need new methods that are time and cost efficient while providing precise and accurate data across broad spatial scales. This thesis explores the potential of multiple remote sensing technologies along with molecular methods to provide critical information on population distribution, density and connectivity across broad spatial and temporal scales. My research first investigated the potential of drones for chimpanzee population surveys in Tanzania. More specifically, I evaluated drone performance in detecting chimpanzee nests by comparing ground and aerial surveys in the Issa valley, western Tanzania. I found ground and aerial nest numbers to be correlated, with an average of 10% of nests observed from the ground detectable from the air. Although I highlight challenges in using drones for chimpanzee surveys, the study provides guidance for future investigations and emphasises the importance of contrasting background and high-resolution images. Next, using satellite imagery from 1973 and 2018 and a landcover projection for 2027, I model landscape connectivity change for chimpanzees within the Greater Mahale Ecosystem (GME), an area containing nearly all of Tanzanian’s chimpanzees. The model reveals a series of corridors allowing chimpanzee movement throughout the ecosystem, as well as a reduction of connectivity over time likely to continue through 2027. By identifying critical areas for chimpanzee movement, the model provides valuable guidance on where to focus conservation efforts. Finally, using two molecular markers (mitochondrial control region sequences and 10 microsatellite loci), I describe population structure and genetic diversity of Tanzania’s chimpanzees. My analyses confirm historical gene flow between Gombe National Park (GNP) and the GME but also suggest complete interruption of chimpanzee movements between the two areas in recent years. Both genetic markers suggest high genetic diversity with no evidence of inbreeding and a greater mitochondrial DNA diversity within GNP. This surprising result might be explained by potential gene flow with extra-park chimpanzees and evidence of Gombe females preference for genetically dissimilar mates. Results of this study resolve previous contrasting findings on connectivity between GNP and the GME and support the establishment of two conservation units. Together, these chapters demonstrate the diversity of non-invasive technologies that can be applied, not only to help chimpanzee conservation, but also any large-bodied species facing accelerated rates of anthropogenic disturbance.