Blue crane study sobering

Issued by the Namibia Crane Working Group 

Lead post photo shows a pair of Blue Cranes with tiny chicks at Charitsaub in Etosha on 17 January 2013 (photo Wilferd Versfeld).

Blue Crane numbers continue to decline in Namibia.

The latest annual combined aerial/ground crane census for the wet season at Etosha National Park and northwards (8 to 11 April 2013) yielded a maximum total of only 13-15 adult Blue Cranes and one young fledgling (all within the Park) – a further decrease in adult numbers for the wet season from 32 in April 2010, 24 in April 2011 and 18 in March 2012.

Overall, numbers have declined steadily since the totals of 60 (54 adults and six chicks/fledglings) in April 2006 and 1994 (49 adults and eleven chicks/fledglings), and 80 in 1992. Only four pairs of Blue Cranes were recorded breeding this year, producing at least six chicks although only one (17%) survived to fledging.

On the positive side, the April 2013 census provided a total count of 19 Wattled Cranes, including two within Etosha at Andoni, the first record of this species within the Park. This development could be associated with the planned burn that took place at Andoni in July 2012; but climate change may also be playing a factor. The remaining Wattled Cranes were recorded in the Lake Oponono area, together with four Crowned Cranes.

The April 2013 crane survey team (L to R): Hanjo Böhme, Wilferd Versfeld, Mike Scott, Dr Ann Scott, Seth Guim (front), Mathias Patzelt and pilot Dr Nad Brain (automatic photo Nad Brain)

One of the contributing factors to the present low numbers of Blue Cranes could be that the rainfall was lower this year (around 200 mm at Okaukuejo, compared to the long term average of 380 mm) than during the preceding years, and also early. There was very little water in the Pan, while Lake Oponono was also drier.

The cranes breed in the ENP during the summer wet-season months. Once the chicks have been reared and are able to fly, the birds leave the confines of the Park and head northwards. They have been recorded in the Lake Oponono (Omadhiya Lakes) area at such times, where they feed on “uintjies” (Cyperaceae) found in the well-grazed grasslands. However, based on the count data, it has become clear that not all the cranes are present in the Park during the wet season. During some years they have not been counted at Lake Oponono during either the wet or dry season, and it is not known where they go at such times.

Blue Cranes are recorded at times (usually in winter, but not every winter) in the Lake Oponono area. This year there are large expanses of water at this site, but the water levels are lower than in previous years due to the current drought conditions (photo Nad Brain).

In 2006, due to a concern about the apparent decline in numbers of Blue Cranes, the Namibia Crane Working Group initiated a conservation action plan for the species. Numbers, breeding success and distribution have been monitored on a regular basis since then. Twenty-four chicks have been fitted with large green plastic rings each with a unique alpa-numerical code and, together with radio telemetry, have been invaluable for tracking movements between Etosha and Lake Oponono, and determining survival rates. Of the breeding birds this year, five (63%) were ringed and aged 4-7 years old.

However, additional measures are required to track crane movements on a wider scale. Generous funding has been provided by the Enviromental Investment Fund (EIF) of Namibia to fit a Blue Crane with a sophisticated solar leg-mounted GPS satellite transmitter (PTT), and the Namibia Crane Working Group is planning a capture at the first opportunity.

An exciting new record for Etosha National Park: Wattled Cranes (the pair in the centre) together with Blue Cranes at Andoni waterhole in April 2013. However, the Blue Crane may be facing extinction in Namibia (photo Ann Scott)

A satellite transmitter has already been fitted a large, just-fledging juvenile east of Salvadora on 7 April 2011, but unfortunately no further signals were received after 2 May 2011. Until recently, the fate of the bird was not known as the transmitter had not then been recovered. On 29 October 2012 the Ministry of Environment and Tourism (MET) collected a (live) Blue Crane fitted with a transmitter about 120km west of Rundu, at Kahenge.

According to the number of the bird’s metal ring, this turned out to be the above juvenile. Although the bird did not survive, its discovery on the northern border of Namibia represents a milestone in efforts to map the areas used by the cranes. Blue Cranes have also been reported in Caprivi (e.g. in September 2007).

Recent records of Wattled Cranes in south-eastern Angola by Dr John Mendelsohn show a possible overlap with some of these cranes and the above Blue Crane. The group closest to this bird was recorded some 150 km away on 26 October 2012, only three days earlier, and the next two groups to the north on 24 October 2012 (up to 330 km away and five days earlier). In view of the now documented assocation between the two species at Andoni this year, it is not impossible that this Blue Crane could have been sharing habitats with these Wattled Cranes north of the border. These developments raise interesting possibilities about further potential areas that the Blue Cranes could be visiting, including in south-eastern Angola.

All three of Namibia’s crane species are on the Red List: the Blue Crane is Critically Endangered, the Wattled Crane is Endangered, and the Crowned Crane is Near Threatened; all three species are also Globally Threatened. South Africa is the main stronghold for the Blue Crane, with around 20,000 birds although numbers have declined from at least five times this number in the past. The small, satellite population of this species is regarded as a conservation enigma, with – up to now – its ability to survive in an arid, predator-rich environment. The population is also regarded as genetically separate from the South African one.

The Namibia Crane Working Group will continue with the following priority actions in an attempt to ensure the survival of the remining Blue Cranes in Namibia:

• Attempt to fit one or more Blue Cranes with satellite telemetry to determine which areas they visit outside the ENP, as a means to identifying and addressing possible threats in these areas;
• Investigate the possibility of searching for Blue Cranes in south-eastern Angola;
• Monitor numbers during both the wet season and the dry season (when the cranes are more concentrated around water points), to obtain more accurate total population estimates;
• Follow up on the reports of hunting of Blue Cranes in areas outside the Park, with appropriate law enforcement where necessary; and
• Increase awareness and educational activities to address the illegal hunting of cranes and other birds outside the Park.

Without the invaluable, ongoing assistance and support of the many partners in this initiative, it would not be possible to implement the above actions.