Water depth, vegetation height, and offshore distance are critical factors in nest-site selection for Grey Crowned Crane at Lake Ol' Bolossat, Kenya

Abstract

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.

Passive acoustic monitoring detects new records of globally threatened birds in a high-elevation wetland (Free State, South Africa)

“…Our results underscore the importance of protecting this highelevation wetland as a safe habitat for at-risk species utilising grassland-wetland mosaics. We confirmed the presence of species of conservation concern, the Grey Crowned Crane, which forages in the surrounding grasslands in the GGHNP and farmlands beyond (Wamiti et al 2020;Amulike et al 2020), and likely relies on the Kleinspruit Wetland for breeding. We recorded Wattled Crane for the first time in the GGHNP, at the wetland; it is amongst the most "Vulnerable" eastern Escarpment species.…”

Drones as a tool to study and monitor endangered Grey Crowned Cranes (Balearica regulorum): Behavioural responses and recommended guidelines

“…Despite its precarious status, the GCC, like other crane species, exhibits significant potential as an indicator species for wetlandgrassland ecosystems (Austin et al, 2018;Fraixedas et al, 2020;Han et al, 2017;Kanyamibwa, 1993). Grey Crowned Cranes generally aggregate in three kinds of groupings: pairs prior to nesting, families after hatching and flocks after fledging (Wamiti et al, 2020).…”

“…Monitoring this species, especially during their breeding period (when gathered as pairs or families), is challenging as they prefer to nest in dense, inaccessible vegetation among tall reeds in wetlands and inland waterbodies (Fakarayi et al, 2016;Francis et al, 2022;Harris & Mirande, 2013;Olupot, 2016;Wamiti et al, 2020;Wen et al, 2021).…”

“…Despite its precarious status, the GCC, like other crane species, exhibits significant potential as an indicator species for wetland‐grassland ecosystems (Austin et al., 2018 ; Fraixedas et al., 2020 ; Han et al., 2017 ; Kanyamibwa, 1993 ). Grey Crowned Cranes generally aggregate in three kinds of groupings: pairs prior to nesting, families after hatching and flocks after fledging (Wamiti et al., 2020 ). Monitoring this species, especially during their breeding period (when gathered as pairs or families), is challenging as they prefer to nest in dense, inaccessible vegetation among tall reeds in wetlands and inland waterbodies (Fakarayi et al., 2016 ; Francis et al., 2022 ; Harris & Mirande, 2013 ; Olupot, 2016 ; Wamiti et al., 2020 ; Wen et al., 2021 ).…”

“…Grey Crowned Cranes generally aggregate in three kinds of groupings: pairs prior to nesting, families after hatching and flocks after fledging (Wamiti et al., 2020 ). Monitoring this species, especially during their breeding period (when gathered as pairs or families), is challenging as they prefer to nest in dense, inaccessible vegetation among tall reeds in wetlands and inland waterbodies (Fakarayi et al., 2016 ; Francis et al., 2022 ; Harris & Mirande, 2013 ; Olupot, 2016 ; Wamiti et al., 2020 ; Wen et al., 2021 ). The most common method for collecting breeding metrics at crane nest sites is by utilising lengthy, physical on‐foot observations to identify breeding cues followed by wading to nest sites (Wamiti et al., 2020 ; Wen et al., 2021 ).…”