Frequent water drinking by Zanzibar red colobus (Procolobus kirkii) in a mangrove forest refuge

Abstract

Isolated populations of Procolobus kirkii on Uzi Island, Zanzibar, use Rhizophora mucronata-dominated mangrove forest for refuge. Three groups, observed over 14 months, spent up to 85% of total observation time in mangroves with brief excursions to adjacent upland coral rag forest, habitat degraded by human cutting. A large proportion of monkeys' diets consisted of plant parts of five mangrove species. Water drinking was common and 326 water-drinking events were recorded at a rate of up to 0.87 drinks hr(-1). Groups used different strategies to obtain water including licking dew, drinking from treeholes, licking rain off leaves and tree trunks, and drinking from coral rock crevices with Cercopithecus mitis albogularis. Drinking frequency increased with time spent in and consumption of mangroves. Strategies for obtaining water were group-specific and likely the result of learning. Drinking appeared to be an acquired behavior in movement-restricted groups living in a habitat with low plant species diversity and limited salty foods.