Archived 2018 topic: 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 its status was pended, but to enable potential reassessment of the species as part of the 2018 Red List update this post was kept open. A decision has now been made and this topic is now closed.

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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8 Responses to Archived 2018 topic: 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. Lourens Leeuwner says:

    Based on the data we have within the Endangered Wildlife Trust (Wildlife and Energy Programme), I believe the downlisting of the Blue crane should be reconsidered for the following reasons:
    1.Power line collisions involving cranes are very irregular and trends cannot be predicted.
    2.There is an inherent risk in downgrading the cranes status because a key threat in their distribution is not decreasing.
    3.As populations increase, it is likely that collisions will also increase as birds move into areas where no mitigation measures have been implemented on power lines
    4.The statistics we have only reflect those incidents which are reported to us. It is very likely that in reality, the total number of cranes killed is significantly higher although we have records of over 1300 incidents (since 1996). Further concern: areas in their distribution where lands are open and lines aren’t often patrolled. We have no way of knowing what the mortality rates are here.
    Looking closer at the Karoo data from a long term study conducted by the EWT around the efficiency of anti collision mitigation: This shows how severe the impact is: 413 cranes in 9 years and this is only on the three transmission lines forming part of the survey. Cosider lines in WC, KZN and NC which we do not survey? This illustrates in the Karoo that crane mortalities are potentially under reported.

  4. James Westrip (BirdLife) says:

    The following full comment has kindly been provided by Mick D’Alton:

    I largely agree with the statements of Kerryn Morrison above although I am not able to comment on the presumption that the total population is increasing, without more proof. The Western Cape is considered to host approximately 50% of the total population and therefore any decline here will have the largest effect on the total population. Little is also known about inter regional movement and supplementation of local populations from other areas.

    In the Western Cape the preferred crops and agricultural practices are constantly changing and since 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 and an example of this is that summer rainfall can stimulate green growth and possible spraying of both herbicide and insecticide which will seriously affect the food source for developing crane chicks. In contrast this extremely dry year has seen a reduction in breeding and fledging of chicks, also for many reasons related to the dry conditions, such as 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 (Journal of the South African Crane Working Group of the EWT Indwa No 1 October 2003) and still occurs annually. These birds, thought to possibly be cohorts of 2 years old, are extremely vulnerable to predation at this time. They choose areas close to large standing water bodies surrounded by good cover to provide suitable roosting and escape methods which usually entails entering the water and walking and swimming to suitable depths. These birds would suffer large losses if such areas were not available to them at this time of year. It would appear that this year could be one such year as all the normally used vleis are dry.
    Although this has only been recorded in the Western Cape it seems likely that this synchronised moult phenomenon should have occurred wherever cranes did. It is therefore possible that the draining of wetlands throughout the country could have had a major impact on the Blue Crane population.

    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.

  5. James Westrip (BirdLife) says:

    The following full comment has kindly been provided by Jessica Shaw:

    I agree with my colleagues on the range and seriousness of threats facing Blue Cranes, and suggest there are not enough recent population data available to justify changing the status of Blue Crane currently.
    Of the three populations, there seems to have been an increase in numbers in the Western Cape and no marked change in the Karoo. While on the face of things, the largest population in the Western Cape is doing well, it is in a very precarious position because of its reliance on the current agricultural system. Declines here would have a major effect on the overall status of the population. There is some evidence of limited recovery in small areas of the eastern population (KZN), but from very low numbers and range relative to the historic baseline (Hofmeyr 2012, Shaw 2015). Unfortunately we don’t have recent Blue Crane population estimates, and with trend data from different sources (SABAP, CAR, limited aerial surveys) changes in the population are not altogether clear, limiting interpretation. It’s quite difficult I think to give a simple answer to what the overall population trajectory might be with different pictures in different areas, and really difficult to project forwards without knowing how the different threats might impact the species in the future.
    Power lines are a major and increasing threat throughout the range of Blue Cranes, with the vast majority of lines unmitigated. The figure of 12% Overberg annual power line mortality comes from surveys on transmission and distribution lines in 2008/9. The average collision rate in this study was 0.10 cranes/km/yr (95% CI 0.04-0.20) unadjusted for survey biases (e.g. removal by scavengers), or 0.31 cranes/km/yr (95% CI 0.13–0.59) adjusted for survey biases (Shaw et al 2010). A subsequent study in 2009-2011 at a transmission line site in the central Karoo gave higher unadjusted collision rates of 0.41 (95% CI 0.21-0.77) cranes/km/yr (Shaw 2013). These results highlight the magnitude of anthropogenic mortality suffered by this species. Given that these birds are long-lived, it is highly likely that they would be unable to sustain such significant mortality rates if conditions become less favourable as a result of the various developmental, environmental or climate change threats that my colleagues have mentioned.
    Additonal refs:
    Hofmeyr, S. 2012. Impacts of environmental change on large terrestrial birds species in South Africa: insights from citizen science data. PhD thesis, University of Cape Town.
    Shaw, J.M. Jenkins, A.R., Smallie, J.J. & Ryan, P.G. 2010. Modelling power-line collision risk for the Blue Crane Anthropoides paradiseus in South Africa. Ibis 152:590-599.
    Shaw, J.M. 2013. Power line collisions in the Karoo: conserving Ludwig’s Bustard. PhD thesis, University of Cape Town.

  6. Ann & Mike Scott, Namibia Crane Working Group says:

    Blue Crane numbers in Namibia have declined as follows: 107 (1970s), 138 (1976), 80 (1988) 60 (1994); and maximum 54 (2006), 30 (2007), 29 (2008), 35 (2009), 31 (2010), 35 (2011) (Namibia Crane Working Group in litt.; Simmons 2015). More recent counts (2012-2016) reached a maximum of 23 only, with an isolated count of 32 in 2017 (Namibia Crane Working Group in litt.).
    The reasons for the above decline are still not confirmed. Potential threats to the Namibian population include expanding human populations and the encroachment of local people with cattle into the grasslands north of Etosha National Park (areas used by the cranes during the dry season); the role played by cranes in the local tradition, including medicinal value; natural predation; and the effects of long-term changes in rainfall patterns coupled with borehole drilling on the springs around the Etosha Pan, which are used for breeding sites by the cranes during the wet months. The above threats, together with inbreeding effects if genetic heterogeneity has been lost, could push such a small population to extinction within a few generations (Simmons 2015).
    From the perspective of the Namibian population, we therefore recommend that the proposed down listing of the species be reconsidered.
    Reference: Simmons RE. 2015. Blue Crane, In: Simmons RE, Brown CJ, Kemper J. Birds to watch in Namibia: red, rare and endemic species. Pp. 60-63. Ministry of Environment and Tourism and Namibia Nature Foundation, Windhoek.
    http://www.the-eis.com/atlas/sites/default/files/Blue_Crane.pdf

  7. Tanya Smith says:

    I would like to support the comments posted by my colleagues and fellow experts in crane biology in Southern Africa, in particular those posted by Jessica Shaw with regards to population trends of all three ‘sub-populations’. A major contributing factor to the proposed downlisting of Blue Cranes is the evidence of an increasing population within the Western Cape, home to an estimated 50% of the global population. Although this is not disputed, we need to acknowledge recent MSc research studies. Including understanding survival, landscape movement, home range and farmer tolerances to Blue Cranes.
    Some key findings from the recent research conclude that Blue Crane adult survival in the Western Cape is significantly lower than the estimated adult survival of Blue Cranes in the Karoo, with an estimated survival of 0.72 for adults. Juvenile survival and immature survival were calculated at 0.6 and 0.87 respectively, higher than survival estimates for the same age classes of Blue Cranes in the Karoo (0.53 and 0.73, respectively). This is expected as the Western Cape breeding productivity for Blue Cranes should be higher due to increased food and water availability and lower predator abundance. However, the low adult survival estimates in the Western Cape (0.72 compared to 0.96 in the Karoo) is a major concern and one that needs to be considered in the global down listing of the species. Ring loss may be a contributing factor to the low adult survival estimate in the Western Cape, however it’s important to note that the same colour ringing technique and materials are used in the Western Cape, Karoo and the Eastern Grasslands, yet adult survival estimates from the Karoo are as expected for healthy populations of long lived species like the Blue Crane (0.96). Blue Cranes move locally and regionally with average distance movements from an individually defined centroid of less than 15 km and regional fidelity being very high as less than 4% of marked and tracked birds being seen outside of their natal region. The localised movements and limited seasonal influence on movement of Blue Cranes in the Western Cape has significant bearing on the conservation and management of the species in the region. This and the fact that the birds are dependent on a ‘man-made’ agricultural landscape makes the population vulnerable to local threats both the current footprint and the well documented future expansion of these threats (powerlines and wind farms). Compounded by climate change effects we are currently witnessing in the Western Cape and we fear that the Western Cape may be an ecological trap for the species. Therefore, we are currently undertaking a PhD study over the next three years in partnership with the Fitzpatrick Institute for African Ornithology to understand the future of our Blue Crane population.

    The threat of accidental poisoning is still very real in the Western Cape, with 16 confirmed deaths in three events over the past year in the Western Cape – although the cause of deaths was not conclusive, post mortems revealed exposure to organo-phosphates. In terms of conflict with farmers and resulting in poisoning of cranes as a result of crop damage there is a significant difference in tolerance between farmers of the Swartland and the Overberg, with more than 60% of interviewed Swartland farmers perceiving Blue Cranes as the most damaging of birds on their farms. Thus making them vulnerable to conflict and resulting actions taken by farmers, such as poisoning.
    In addition, it is important to consider that other than the Western Cape sub-population, Blue Crane numbers in the Karoo (more than 30% of our global population) are stable at best as suggested by the available population trend data such as SABAP2 and CAR (Coordinated Avifaunal Roadcount) data, whilst the Eastern Grasslands – although showing increases in KwaZulu-Natal thanks to annual aerial surveys conducted – is home to a very small proportion of the population thus the increases demonstrated have a minor effect of the overall global population.
    We must therefore consider carefully the very real and current threats in the Western Cape that will (and do) have an impact on Blue Cranes based on past and current research. The long-lived nature of Blue Cranes can delay the visible effect of these threats on the population and it is therefore premature to down list this species given the real threats have been demonstrated to impact on this species and the fact.

    References:
    Julia L van Velden, Res Altwegg, Kevin Shaw & Peter G Ryan (2016): Movement patterns and survival estimates of Blue Cranes in the Western Cape, Ostrich, DOI: 10.2989/00306525.2016.1224782

    Julia L van Velden, Tanya Smith & Peter G Ryan (2016). Cranes and Crops: Investigating Farmer Tolerances toward Crop Damage by Threatened Blue Cranes (Anthropoides paradiseus) in the Western Cape, South Africa, Environmental Management, DOI: 10.1007/s00267-016-0768-1

    Sydney Davis (2018, in press). Blue Crane Movement and Landscape Use in the Western Cape, MSc Thesis.

  8. James Westrip (BirdLife) says:

    Preliminary proposals

    Based on available information, our preliminary proposal for the 2018 Red List would be to list Blue Crane as Vulnerable under criterion A3cde.

    There is now a period for further comments until the final deadline in mid-July, after which the recommended categorisations will be put forward to IUCN.

    Please note that we will then only post final recommended categorisations on forum discussions where these differ from the initial proposal.
    The final 2018 Red List categories will be published on the BirdLife and IUCN websites in November, following further checking of information relevant to the assessments by both BirdLife and IUCN.

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