# Demography of reintroduced Mount Kenya guereza (Colobus guereza kikuyuensis) at Karura Forest, Kenya

## TL;DR

This study shows that reintroducing Mount Kenya guerezas in Karura Forest, Kenya, was successful over 8 years, with growing populations and adaptation to the environment.

## Contribution

The study provides empirical evidence of successful reintroduction of Mount Kenya guerezas and their demographic trends in a restored forest.

## Key findings

- Reintroduced guereza groups showed annual increases in births and group size, indicating successful adaptation.
- Fourteen reintroduced groups settled in riverine zones, with primary causes of death linked to arboreality adaptation.
- By 2023, 109 births were recorded, and group numbers increased to 31 due to natal dispersal.

## Abstract

Between May 2014 and March 2016, 22 groups of Mount Kenya guerezas (Colobus guereza kikuyuensis Lönnberg, 1912) were reintroduced in Karura Forest, Kenya. To assess the success of the reintroduction, we conducted monthly censuses over 8 years (2016–2023). We determined group size and composition of the reintroduced population. During the censuses, we recorded instances of births, deaths (disappearance), dispersal from natal groups, and the habitat types where groups established home ranges. A total of 14 of the reintroduced groups settled along the riverine zones. Over the years, we recorded an annual increase in the number of births and group size, indicating successful adaptation of the reintroduced primates. Coming from a degraded source habitat, the primary cause of death was related to arboreality adaptation (23 %), and only one case of infanticide during a group takeover was recorded. Group fusion was not observed; however, seven groups with more than two adult males began splitting in 2019. By December 2023, 109 births had been recorded, and groups increased to 31 due to natal dispersal. Our results demonstrate that C. guereza kikuyuensis reintroduction to Karura Forest was a success.