A Reassessment of the Population Size, Demography, and Status of Tanzania’s Endemic Kipunji Rungwecebus kipunji 13 Years on: Demonstrating Conservation Success

Davenport, Tim R.B.; Machaga, Sophy J.; Mpunga, Noah E.; Kimiti, Sylvanos P.; Mwalwengele, Willy; Mwaipungu, Obadia; Makumbule, Pascal M.

doi:10.1007/s10764-022-00281-3

Cited by 5 publications

(3 citation statements)

References 35 publications

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“…Our extended dataset allowed us to assess that following this decline populations remained apparently stable, albeit at very low levels of local abundance, with Tanzania Sykes' monkeys showing sign of recovery in the last 6 years, concomitant with the upgraded level of protection of the poorly protected forest and the initiation in 2017 of a protection program that implements monthly ground patrols lasting 4–5 days by a team of reserve rangers, village game scouts and armed soldiers from the regional anti‐poaching unit (Southern Tanzania Elephant Program, 2021). While the target primate species are relatively long‐lived (Jones, 2011) and hence a lag from the onset of protection to recovery is to be expected (Ewers & Didham, 2006; Nagelkerke et al, 2002), evidence from other studies shows that effective ground protection can be associated with relatively rapid population recovery (e.g., Chapman et al, 2018; kipunji, Rungwecebus kipunji : Davenport et al, 2022).…”

Section: Discussionmentioning

confidence: 99%

Long‐term dynamics of wild primate populations across forests with contrasting protection in Tanzania

et al. 2023

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Anthropogenic activities driving tropical forests' loss imperil global biodiversity and provision of ecosystem services. In this context, systematic monitoring programs evaluating wildlife trends are essential. Non-human primates are relevant conservation targets since they represent vital components of tropical forests by serving as pollinators and seed dispersers. Here, we present primate group counts data collected over 19 years in a primate hotspot in Tanzania. We analyzed data with a hierarchical dynamic model accounting for imperfect detection that estimates local group abundance and temporal rates of change, to assess whether habitat protection explained trends of the arboreal and diurnal Peters' Angola colobus (Colobus angolensis palliatus), Udzungwa red colobus (Piliocolobus gordonorum), and Tanzania Sykes' monkey (Cercopithecus mitis subsp. moloneyi). We targeted populations occurring in two forest blocks with contrasting protection regimes, with one block impacted by targeted poaching of the two Colobus species. We found that these latter species were much less abundant in the more human impacted forest, underwent a rapid decline, and subsequently remained at low abundance and without signs of recovery once this forest was granted greater protection. Instead, Sykes' abundance did not differ between forests, and improved protection was associated with a slight increase in abundance.Age class composition for social groups of both Colobus species differed between forests, indicating altered births and survivorship rates in the impacted forest. Results suggest that targeted hunting can prevent recovery for several years and even after increased habitat protection. Our approach appears valuable to monitor population dynamics over the long term, highlighting species-specific variations in both vulnerability to anthropogenic disturbance and recovery patterns in primate populations.

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Section: Discussionmentioning

confidence: 99%

Long‐term dynamics of wild primate populations across forests with contrasting protection in Tanzania

et al. 2023

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“…Therefore, research and conservation efforts focused on primates may have the added benefits of preserving important ecological functions as well as other species (Gippoliti & Sousa, 2004; Lambert, 2010; Martins & Valladares‐Padua, 2005). However, the quantitative knowledge on abundance, conservation status, and vulnerability of threatened primates needed to promote sound conservation remains limited (Estrada et al, 2017), and rarely does this cover the entire range of species (e.g., Davenport et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

Calibrating occupancy to density estimations to assess abundance and vulnerability of a threatened primate in Tanzania

Greco

Paddock

McCabe³

et al. 2023

Ecosphere

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The current decline of mammals worldwide makes quantitative population assessments crucial, especially for range‐restricted and threatened species. However, robust abundance estimations are challenging for elusive or otherwise difficult to detect species. Alternative metrics requiring only presence/absence data, that is, occupancy, are possible but calibration with independent density estimates should be foreseen, although rarely performed. Here, we calibrated density estimates from acoustic surveys to occupancy estimates from camera‐trapping detections to derive the abundance of the endangered Sanje mangabey (Cercocebus sanjei) across its entire range in the Udzungwa Mountains of Tanzania. We found marked occupancy–density relationships for the two forest blocks where this primate occurs and used them to derive spatially explicit density estimates. Occupancy increased in montane forest zones at mid‐elevation but decreased slightly with proximity to forest borders. We predicted an average density (±SE) of 0.26 ± 0.05 groups/km2 in the national park and 0.24 ± 0.06 in the nature reserve. Accordingly, and given the much larger area of the reserve, the average predicted individual abundance was 1555 ± 325 and 2471 ± 571 in the national park and nature reserve, respectively. We found higher density and abundance in the nature reserve compared with previous studies. Given the past disturbance and poorer protection in the nature reserve relative to the national park, our results instill optimism for the status of the species, although occupancy analysis highlighted the potential vulnerability of this primate to human disturbance. Our approach appears valuable for spatially explicit density estimations of elusive species, and provides robust assessments of vulnerability and identification of priority areas for conservation of threatened populations.

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“…Many primate species are threatened, and an understanding of their population status and factors that contribute to their threatened status is crucial for developing informed conservation strategies (Estrada et al, 2017). The evaluation of population and habitat conservation requires long-term field monitoring, such as the monitoring of the primate populations of Kibale National Park, Uganda (Chapman et al, 2010;Sarkar et al, 2021) and of kipunjis (Rungwecebus kipunji) in Tanzania (Davenport et al, 2022). However, such long-term field data often are lacking (Kleiman et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

The Critically Endangered Hainan Gibbon (Nomascus hainanus) Population Increases but not at the Maximum Possible Rate

Liu

et al. 2022

Int J Primatol

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With the ongoing global biodiversity crisis in the Anthropocene, it is critical to understand how to save endangered species to “bend the curve” of biodiversity decline. The Hainan gibbon (Nomascus hainanus) is a Critically Endangered species that is endemic to Hainan Island. We performed two synchronized total count surveys in Hainan Tropic Rain Forest National Park in November and December of 2020 and 2021 by locating gibbon groups from their morning calls and conducting detailed counts in all potential habitat fragments. We compared our findings with existing data to model the population trend, and analyzed the potential and realized reproductive potentials. We found 5 groups with a total of 33 gibbons in 2020 and 35 in 2021, including 4 and 6 solitary individuals respectively. This is an increase of 169% since 2003, when there were 13 individuals with 2 groups and 2 solitary individuals. Logistic and linear curves fitted the 2003-2021 population census data equally well. Although the population is growing, it has not realized its full reproductive potential (when all adult females give births at 24-month intervals), suggesting that external factors like available habitat, as well as nutritional, physiological, and behavioral factors may be limiting the population. The gibbon’s recovery demonstrates that establishing a nature reserve with regular patrols, banning logging, curbing poaching, and environmental education have been effective. Because the Hainan gibbon population is still extremely small, carefully planned conservation actions, including an ambitious forest restoration program, will be needed to ensure the species’ continued survival.

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A Reassessment of the Population Size, Demography, and Status of Tanzania’s Endemic Kipunji Rungwecebus kipunji 13 Years on: Demonstrating Conservation Success

Cited by 5 publications

References 35 publications

Long‐term dynamics of wild primate populations across forests with contrasting protection in Tanzania

Long‐term dynamics of wild primate populations across forests with contrasting protection in Tanzania

Calibrating occupancy to density estimations to assess abundance and vulnerability of a threatened primate in Tanzania

The Critically Endangered Hainan Gibbon (Nomascus hainanus) Population Increases but not at the Maximum Possible Rate

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