Blue Crane (Anthropoides paradiseus): downlist to Near Threatened?

This discussion was first published as part of the 2017 Red List update. At the time a decision regarding the status of several was pended, but to enable potential reassessment of these species as part of the 2018 Red List update this post remains open and the date of posting has been updated.

Blue Crane Anthropoides paradiseus is endemic to southern Africa with the majority of the global population found in South Africa, a small population in Namibia (c.35 individuals at Etosha [Simmons et al. 2006, K. Morrison in litt. 2012]), and rare sightings in Lesotho (K. Morrison et al. in litt. 2007). There was a potentially small population in Swaziland (c.12 birds) (Parker 1994), but the species is suggested to have disappeared from the country at some point between 1995 and 1998 (Shaw 2015). Occurring in grassland habitats, afforestation has been a significant threat to this species in the past and has been thought to have contributed to population declines and its disappearance from Swaziland (Monadjem et al. 2003). Development of mining and agriculture also are leading to the loss of habitat, while poisoning may also cause some mortality (though thanks to increased awareness deliberate poisoning has reduced) (Shaw 2015). The final major threat that is currently impacting this species is the expanding power-line network, with c.12% of the Overberg population potentially being killed annually due to collisions with power-lines (Shaw et al. 2010).

Despite all of these threats some populations are doing well, with the KwaZulu-Natal population potentially having increased by c.45% over the preceding decade (Shaw 2015). Comparing population estimates from McCann (2000) and McCann et al. (2007) also led the recent 2015 Eskom Red Data Book of South Africa, Lesotho and Swaziland (Shaw 2015) to suggest that there may have been a regional increase of 18% in that time period. However, it also suggested that the original estimates may have been low, and further suggest that the population may have actually undergone a decline of 15% over the past 3 generations (39 years), with a suggestion that the threat level may rise in the future (Shaw 2015). Accordingly the species was assessed on the regional Red List as Near Threatened under criterion A2acde. Suitable habitat continues to under severe threat of degradation and destruction thanks to open cast coal and uranium mining, agriculture and potential gas extraction (K. Morrison in litt. 2016), with the potential for significant future habitat loss. Further development of power-lines and wind farms as well as capture for trade have also been suggested to be potential threats that could impact this species further in the future (K. Morrison in litt. 2016). On the basis of this, the species was globally retained as Vulnerable, but under criterion A3cde (see BirdLife International 2017).

Following a period of review, it has been suggested that the category this species is listed under may be revised. The putative 15% decline over the past 3 generations (Shaw 2015) is insufficient for a listing as Near Threatened, as it does not approach the threshold for Vulnerable under criterion A2 (30% decline over 3 generations). Additionally, this species is undergoing a short-term increase despite the current threats faced by this species. This at least suggests that the species may be able to cope with some of the future threats too and future declines may not be too severe. However, given that the 3 generation period is fairly long for this species it may be most appropriate to suspect that this species may decline in the future, and the decline may approach the threshold for Vulnerable. Therefore, it is proposed that this species be listed as Near Threatened under criterion A3cde.

 

References

McCann, K. I. 2000. Blue Crane Anthropoides paradiseus. In: Barnes, K. N. (ed.) The Eskom Red Data Book of the Birds of South Africa, Lesotho and Swaziland, pp 92-94. BirdLife South Africa, Johannesburg, South Africa.

McCann, K.; Theron, L-J.; Morrison, K. 2007. Conservation priorities for the Blue Crane (Anthropoides paradiseus) in South Africa – the effects of habitat changes on distribution and numbers. Ostrich 78(2): 205-211.

Monadjem, A.; Boycott, R. C.; Parker, V.; Culverwell, J. 2003. Threatened vertebrates of Swaziland: Swaziland red data book: fishes, amphibians, reptiles, birds and mammals. Ministry of Tourism, Environment and Communications, Mbabane, Swaziland.

Parker, V. 1994. Swaziland bird atlas 1985–1991. Webster’s, Mbabane.

Shaw, J. M. 2015. Blue Crane Anthropoides paradiseus. In: Taylor, M. R.; Peacock, F.; Wanless, R. M. (ed.), The 2015 Eskom Red Data Book of Birds of South Africa, Lesotho and Swaziland, pp. 291-293. BirdLife South Africa, Johannesburg, South Africa.

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3 Responses to Blue Crane (Anthropoides paradiseus): downlist to Near Threatened?

  1. Kerryn Morrison says:

    I do agree that the Blue Crane population in South Africa is currently on the increase. However, I would caution strongly against down listing the species at this time. This is due to a number of threats that are currently showing no signs of abating and a number of potential threats that are emerging in parts of the distribution range of the Blue Crane.
    The stronghold for the species is the agriculturally transformed wheat / pasture mosaic of the Western Cape in South Africa. Acting as an ideal habitat for cranes, their breeding productivity is currently above what it would be in natural habitat (Hofmeyer 2012). This is due to the fact that pastures provide an open landscape and a highly nutritious habitat, within which artificial stock feeding areas provide additional nutrition, in the winter months. In the spring, the winter growing wheat cultivar is harvested, providing a highly suitable open, short vegetated breeding habitat together with the pastures. However, climate change models predict that weather patterns will change significantly in this area. This, together with the changing socio-economic situation in the country, will likely result in a change in the agriculture landscape over time. A changed landscape will likely affect the breeding productivity of the cranes. A decline in breeding productivity, together with the 12% mortality through power line collisions (Shaw et al. 2010), could result in a declining population.
    Wind turbines in the Western Cape have resulted in only a small number of Blue Crane mortalities to date. However, there is likely to be a significant increase in wind farms across the area in the near future. Our understanding therefore of the ultimate impact is limited and will only be understood once they are operational. However, we do know that power lines are one of the key threats to cranes, and that each wind farm established will result in associated power line infrastructure. This increases the mortality threat to Blue Cranes in the Western Cape, which will also increase over time.
    The largest population of Blue Cranes in natural habitat occurs in the Karoo of South Africa. The majority of the distribution range of the Blue Crane in the Karoo is currently under consideration for hydraulic fracturing. The cranes in this part of their range are completely reliant on artificial and natural water resources that rely on underground water. Should fracking go ahead in the Karoo we do not know what the consequences on the Blue Crane population here would be.
    Finally, Blue Cranes are also found across the eastern grasslands of South Africa. Although declining across most of their distribution range here, small increases have been recorded on the Drakensberg region. However, predictions exist that by 2025, KwaZulu-Natal would have passed its threshold of resistance with more than 50% of the province transformed. For Mpumalanga, the habitat transformation is as dramatic with more that 50% of the province already under mining or under mining application.
    For these reasons, I would strongly recommend taking a precautionary approach at this time, and not down list the species.

  2. Andy Symes (BirdLife) says:

    Preliminary proposals

    Based on available information, our proposal for the 2017 Red List would be to pend the decision on this species and keep this discussion open until 2018, while leaving the current Red List category unchanged in the 2017 update.

    There is now a period for further comments until the final deadline of 4 August, after which the recommended categorisations will be put forward to IUCN.

    Final 2017 Red List categories will be published on the BirdLife and IUCN websites in early December, following further checking of information relevant to the assessments by both BirdLife and IUCN.

  3. Mick D'Alton says:

    I largely agree with the statements of Kerryn Morrison, but there is no proof of total population increasing. The Western Cape has approximately 50% of the total population and is therefore a priority.Little is also known about inter regional movement and supplementation of local populations from other areas.
    In the Western Cape crops and agricultural practices are constantly changing and the birds utilise the agricultural lands. These changes in practices could have severe impacts on breeding and foraging opportunities. Climate change is exacerbating this problem requiring untimely chemical interventions which could seriously affect the food source for developing crane chicks. This extremely dry year has seen a reduction in breeding and fledging of chicks due to lack of accessible water for drinking and roosting in and a lack of suitable forage.
    Synchronised flightless moulting of large numbers of Blue Cranes has been recorded on the Agulhas Plain (Indwa No 1 October 2003) and still occurs annually. These birds are extremely vulnerable to predation at this time. They need large water bodies to provide suitable roosting and escape methods and this year all the normally used vleis are dry.
    I believe that the evidence is not sufficient to warrant a downlisting and would advocate the precautionary principle until more and better population data is sourced.

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