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
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 in the Caatinga biome in Northeastern Brazil. Although Caatinga is commonly known as a vast scrubland with dry landscapes and cacti, it wasn't always like this. Caatinga means "white forest" in the indigenous Tupi language, referring to the region's dry forests that were once the main vegetation. Unfortunately, human activities have heavily impacted 63% of the Caatinga, with only 7% being 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 by the IUCN and Brazilian Red Lists. Titi monkeys, specifically the blond titi, 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 helped shed light on their distribution and abundance.
In a previous project funded by The Mohamed bin Zayed Species Conservation Fund, playback sampling was used to reveal that the blond titi is more widespread and abundant than previously known. Its occurrence was confirmed in a conservation priority protected area (Alonso et al., 2022). The project also provided the first accurate estimate of the population size, which amounted to 273 adult blond titi monkeys in a 221‐km2 area in Boa Vista do Tupim, Bahia state (Coelho et al., 2020). However, the project also delivered concerning news: forest cover continues to decrease (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 main 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 utilized 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 observed in the Baixão and Pati areas, where the probability of occurrence was less than 12%, as determined by occupancy modeling (Figure 5).
Estimating the number of individuals within protected areas is a crucial goal of the blond titi Conservation Action Plan. Understanding the population size in different areas of the Chapada Diamantina National Park is essential for park management and regional planning to promote connectivity between the remaining Caatinga forests. The results of this project also aim to raise public awareness about the conservation of blond titi monkeys and their habitats – the "white forests" that we much need in their original place.
References and Links
Alonso et al. (2022)
Coelho et al. (2020)
Chapada Diamantina National Park
Conservation Action Plan of Primates in Northeastern Brazil
All data, analyses, and accompanying publications are being updated and publicly accessible on the Open Science Framework at https://osf.io/d2cvw/files/osfstorage
- Fig1. Five study areas surveyed from 2021 to 2023 to estimate the abundance of the blond titi monkey in Chapada Diamantina National Park, Brazil
- Fig2. Sampling sites in the five study areas surveyed from 2021 to 2023 to estimate the abundance of the blond titi monkey in Chapada Diamantina National Park, Brazil
- Fig3. Location of 212 playback survey points conducted from 2021 to 2023 in Chapada Diamantina National Park and surroundings, Brazil
- Fig4. Number of blond titi monkey groups estimated in Marimbus and Chapadinha study areas in the Chapada Diamantina National Park, Brazil
- Fig5. Probability of occurrence of the blond titi monkey in 212 sampling sites in the Chapada Diamantina National Park, Brazil
- Table 1. Abundance of the bond titi monkey predicted in three study areas in Chapada Diamantina National Park, Brazil
Project 222529779 location - Brazil, South America