Grey Crowned Crane Balearica regulorum is described as an icon of Africa’s wetlands and grasslands and is listed as Endangered on the IUCN Red List of Threatened species. Conservation efforts are partially hindered by lack of information on factors influencing breeding productivity, such as nest-site selection. Factors influencing nest-site selection were investigated at Lake Ol’ Bolossat, a 43.3 km2 wetland located in the central Kenya from 30 paired nests. Generalized Linear Mixed-Effects Models were used to analyse the relationship between factors influencing nest-site selection by cranes and variables that were predicted to have a compelling influence on nest-site selection besides i) food and nesting materials availability i.e. the offshore distance of the nest and water depth, and ii) nest concealment and susceptibility to predation i.e. vegetation height and grazing intensity. Results show that variables which had a significant influence on nest-site selection were: water depth (p=0.005), the offshore distance from the nest (p=0.037), and vegetation height (p=0.035). Cranes located their nests in water points above 50 cm deep, vegetation height of 60-90 cm, and preferably 100 m offshore. A minimum of 103 territorial pairs, both breeding and non-breeding cranes, were recorded. The middle section of the lake had the highest number (52), while north and south had 32 and 19 pairs respectively. The mean distance between any two pairs was 302.53±17.02 (SE) meters. This study sheds some light on the understanding of characteristics of Grey Crowned Crane’s nesting sites that will facilitate manipulation and management of breeding sites. Lake Ol’ Bolossat is consequently a critical breeding site with a substantial role in the species’ population recovery and survival. A wetland management option that aims at achieving sustainable use of lake’s resources by local communities without compromising needs of wildlife is highly commended.
Grey Crowned Crane Balearica regulorum is described as an icon of Africa’s wetlands and grasslands and is listed as Endangered on the IUCN Red List of Threatened species. Efforts towards its conservation actions are nonetheless hindered by among others, lack of knowledge on factors influencing breeding productivity such as nest-site selection. Factors influencing the probability of nest-site selection were investigated at Lake Ol’ Bolossat, a 43.3 km2 wetland located in the central Kenya highlands as a breeding resident. The number and distribution pattern of breeding pairs was also determined. A total of 123 breeding pairs were recorded, 103 in the lake and 20 in the surveyed satellite wetlands thus providing the largest database of breeding Grey Crowned Cranes reported in Kenya to date. Mean breeding pair density for the lake’s marshes was 6.50±0.84 (SE) pairs/km2 with a mean distance between nests of 302.53±17.02 (SE) m. Generalized Linear Models were used to select the most important environmental variables explaining nest-sites selection. The model selection algorithm yielded a subset of 8 best models, where the most important predictor variables (i.e. those with ΔAICc <2) were determined as water depth (preferred above 50 cm), vegetation height (above 60-90 cm) and distance from the water edge (ca.100 m). Water depth and vegetation height had positive effects on nesting probability while the distance to water edge exhibits quadratic tendency. These findings provide key insight into Grey Crowned Crane nesting ecology and a basis for breeding habitat modification and management. This study underscores the importance of Lake Ol’ Bolossat as a critical breeding site and its significant role in the species’ population recovery and survival. The lake should consequently be re-gazetted as a National Park to ensure effective and sustainable control of anthropogenic activities in and around the lake in favour of Grey Crowned Crane.