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blond titi monkey (Callicebus barbarabrownae)

Mohamed bin Zayed Species project number 222529779

The population size of the Critically Endangered blond titi monkey in the Chapada Diamantina National Park, Brazil

Mohamed bin Zayed Species Conservation (Project No. 222529779) - blond titi monkey - Awarded $12,500 on October 24, 2022

Igor Pfeifer Coelho and André Chein Alonso

 

The goal of this project was to estimate the abundance of the critically endangered blond titi monkey in the only conservation priority protected area where it is known to exist. Our findings revealed that the Chapada Diamantina National Park is home to the largest population and highest known density of the species.

 

The blond titi monkey inhabits forests within the Caatinga biome in Northeastern Brazil. Although the Caatinga is commonly associated with vast scrublands, dry landscapes, and cacti, it wasn't always this way. "Caatinga" means "white forest" in the indigenous Tupi language, referring to the region's once-dominant dry forests. Unfortunately, human activities have severely impacted 63% of the Caatinga, and only 7% of this biome is within protected areas. Additionally, 94% of the region faces the moderate to high risk of desertification due to land use and climate change.

The blond titi monkey was only discovered 30 years ago and is considered highly threatened with extinction, according to the IUCN and Brazilian Red Lists. Blond titi monkeys are difficult to spot visually as they are shy and cryptic, living in small territorial groups averaging three adults. However, they emit loud calls for intergroup communication and respond to playback calls, which has aided in studying their distribution and abundance.

In a previous project funded by The Mohamed bin Zayed Species Conservation Fund, playback sampling revealed that the blond titi is more widespread and abundant than previously thought. Its presence was confirmed in a conservation priority protected area (Alonso et al., 2022). The project also provided the first accurate estimate of the population size, estimated to 273 adult blond titi monkeys within a 221‐km2 area in Boa Vista do Tupim, Bahia state (Coelho et al., 2020). However, the project also highlighted alarming trends: forest cover continues to decrease (an 11% loss from 2005 to 2016), and human occupation is rapidly expanding in the species' range (67% increase from 2005 to 2016; Alonso et al., 2022).

From 2021 to 2023, five major forested areas in the Chapada Diamantina National Park were surveyed using playback calls to count blond titi groups at 212 sampling sites (Figs 1, 2 and 3). N-mixture and occupancy models were employed to predict group abundance in each area and the species' occurrence in the region. The estimated total population was 873 individuals, with the highest density found in the Chapadinha study area (Table 1). The species was not detected in the Baixão and Pati areas, where the probability of occurrence was less than 12% (Figure 5).

Estimating the number of individuals within protected areas is a key objective of the blond titi Conservation Action Plan. Understanding population sizes across different areas of the Chapada Diamantina National Park is essential for park management and regional planning to promote connectivity between the remaining Caatinga forests. This project's findings also aim to increase public awareness about the conservation of blond titi monkeys and the preservation of their habitats – the "white forests" we need in their original place.

 

All data, analyses, and accompanying publications are being updated and publicly accessible on the Open Science Framework at https://osf.io/d2cvw/

 

References and Links

Alonso et al. (2022)
https://link.springer.com/article/10.1007/s10764-021-00269-5

Coelho et al. (2020)
https://onlinelibrary.wiley.com/doi/abs/10.1002/ajp.23126

Previous project
https://www.speciesconservation.org/case-studies-projects/blond-titi-monkey/13903

Chapada Diamantina National Park
https://www.icmbio.gov.br/portal/visitacao1/unidades-abertas-a-visitacao/9396-parque-nacional-da-chapada-da-diamantina

 

Conservation Action Plan of Primates in Northeastern Brazil
https://www.icmbio.gov.br/portal/faunabrasileira/plano-de-acao-nacional-lista/865-pan-primatas-do-nordeste

Project documents