Namibia Crane and Wetland Bird Conservation Project

Blue Cranes Anthropoides paradiseus are the world's most range-restricted crane species and occur mainly in South Africa, with three discrete sub-populations. However, a curious and highly isolated breeding population of these cranes also occurs in Namibia, over 1 000km north of any other population. The birds occur within Etosha National Park and on the grasslands to the north, and pose a genetic and conservation puzzle - how does this particular population survive without mixing with South African birds and in particular, within the predator-rich Etosha National Park?

From a conservation point of view they are classified as Critically Endangered in Namibia because of their tiny population size and the 25% decline in numbers since the late 1980s. This project assesses conservation and ecological factors that have shaped this population and compares them with what is known about South Africa's Blue Cranes, as a basis for a conservation strategy for the Blue Crane population in Namibia.

This two-year study aims to determine the reasons for the small and possibly declining population of Blue Cranes through population size monitoring, and identify the factors critical in the ecology and life-history of these birds in Namibia. Two students will benefit from training and supervision, and a Species Management Plan for the cranes will be one of the outcomes, along with some papers in scientific journals on this critically endangered species.

Background
Population size in Etosha National Park was estimated at 80 birds in 1989 but by 1994 this tiny population had declined to only 60 birds, comprising 49 adults and 11 juveniles. Apart from an isolated high count of 138 birds in July 1976, there are no further records of the population size ever exceeding 100 birds.

The species as a whole does not seem to migrate far, and Namibian birds are known to move locally only within the Etosha NP area, where the birds have been observed to descend in the evening from high level to waterholes, where they roost. The fact that there are very few records of movements from elsewhere suggests that Etosha is probably a closed system.

Blue Cranes occur primarily in dry grassland habitat where water regularly occurs. In the arid grasslands of Etosha the favoured areas are the perennial springs around the pan edge and isolated waterholes in grassy plains. Nests occur on the ground in open grassy areas, not far from water, so that chicks may be led to water to drink and escape predators. The cranes feed on seeds and flowers from grasses, and frogs, reptiles and fish; in Etosha they regularly turn over elephant and ungulate dung to consume dung beetles and other insects.

Isolated and small populations can be prone to inbreeding effects if genetic heterogeneity has been lost; this could apply to Etosha's cranes, given the small breeding population estimated at just 24 pairs, and their apparent genetic isolation (M Wink in litt.). This, disease and catastrophic events such as severe drought under global climate change could push such a small population to extinction within a generation or two.

Methodology
The current size and age composition of the Namibian Blue Crane population is being addressed by means of a national survey of the species. It began in March 2007 with an aerial survey by the Namibia Crane Working Group to determine any breeding areas - followed up by ground observations and includes an estimate of the adult: juvenile ratio. A second survey of all likely waterholes, through a coordinated ground count by volunteers and MET staff, will take place at the height of the dry winter season.

Habitats used by Blue Cranes in the Etosha area on a seasonal basis are being investigated and include the use of space during the breeding season as opposed to during the winter (dry) season, as well as limiting factors in terms of breeding habitat, in relation to predators and diet and use of nearby water.

Behaviour and breeding success is being investigated, for example timing, nest site selection, feeding behaviour and survival. This project is collaborating with a comprehensive study being undertaken to compare Namibian and South African Blue Crane genetic samples by collecting blood samples. Genetic sampling will be informative as to whether this population is inbred and thus something of its immediate history.

The participation of all crane workers and supporters in Namibia (including the Ministry of Environment and Tourism) and elsewhere will be promoted through the Namibia Crane Working Group - headed by coordinators Ann and Mike Scott, who also have longstanding links with the Overberg Crane Group, Western Cape; the EWT South African Crane Working Group; and the International Crane Foundation. One of the aims of the project is to build capacity for Namibian conservationists.

A Species Management Plan will be formulated once the results from this two-year survey are available.