Cardiff University | Prifysgol Caerdydd ORCA
Online Research @ Cardiff 
WelshClear Cookie - decide language by browser settings

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

Greco, Ilaria, Paddock, Christina Lynette ORCID:, McCabe, Gráinne Michelle, Barelli, Claudia, Shinyambala, Steven, Mtui, Arafat S. and Rovero, Francesco 2023. Calibrating occupancy to density estimations to assess abundance and vulnerability of a threatened primate in Tanzania. Ecosphere 14 (3) , e4427. 10.1002/ecs2.4427

[thumbnail of ecs2.4427.pdf] PDF - Published Version
Available under License Creative Commons Attribution.

Download (1MB)


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.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Biosciences
Additional Information: License information from Publisher: LICENSE 1: URL:
Publisher: Wiley Open Access
ISSN: 2150-8925
Date of First Compliant Deposit: 8 March 2023
Date of Acceptance: 29 November 2022
Last Modified: 03 May 2023 17:55

Actions (repository staff only)

Edit Item Edit Item


Downloads per month over past year

View more statistics