Archived 2017 topics: Brown-necked Parrot (Poicephalus robustus) is being split into P. robustus and P. fuscicollis: list P. fuscicollis as Least Concern and P. robustus as Vulnerable?

Following a taxonomic reassessment, the Brown-necked Parrot, Poicephalus robustus, is to be split by BirdLife’s Taxonomic Working Group into Cape Parrot, P. robustus, and Brown-necked Parrot, P. fuscicollis. Brown-necked Parrot comprises two subspecies; P. f. fuscicollis, which is found patchily in West Africa, as well as around the lower River Congo and into northern Angola, and P. f. suahelicus which has a more easterly distribution from central Angola across to Tanzania and south to northern Botswana, Zimbabwe, Mozambique and the extreme north-east of South Africa (see Collar 2017). Any potential decline in this species is not thought to be at sufficient a rate to approach the threshold for listing under criterion A. The population has not been quantified but it has been described as ‘patchily common’, but may be ‘generally scarce’ (Collar 2017). Therefore, the Brown-necked Parrot is unlikely to approach the threshold for Vulnerable under any criterion and would warrant listing as Least Concern.

Cape Parrot, P. robustus, is endemic to South Africa, only found in the provinces of KwaZulu-Natal and Eastern Cape with a small outlying population in Limpopo (see Hockey et al. 2005, Collar 2017). The recent Eskom Red Data Book of Birds of South Africa, Lesotho and Swaziland assessed this species as Endangered (Downs 2015), however, assessing this species against IUCN criteria suggests that the species should not be given this as a global Red List status.

The population of P. robustus is assessed annually by the Cape Parrot Big Birding Day. The pilot for this was held in 1997, and has continued every year since then, with the census taking place on a Saturday afternoon/Sunday morning since 2000 (Downs et al. 2014). Population numbers prior to 2002 were below 500, but since then the numbers have been higher (average 1,366 ± 245 individuals between 2008 and 2012, with a high count of 1,786 individuals in 2009) (Downs et al. 2014). However, this is likely to be a consequence of an increase in the coverage of the survey, and in fact the population appears to have been stable over at least the 15 years of surveys incorporated in Downs et al. (2014). The 2016 survey supports this with a maximum number of 1,499 individuals reported (Downs and Singh 2016). In Downs (2015) the population size was listed as 1,100-1,500 mature individuals. However, it is believed that this may actually represent the total number of individuals rather than mature individuals as it was further stated that it was unknown what proportion of these individuals were adults (see Downs 2015). Treating the population estimate of Downs (2015) as an estimate of the total number of individuals would also fit with the estimates presented by Downs et al. (2014) and Downs and Singh (2016). This estimate could be altered to take into account the maximum record of 2009, so that the range is 1,100-1,786 individuals, which would roughly equate to 733-1,190 mature individuals.

As stated above, the population trend at least over the past 20 years appears to be stable, which makes it odd that the species is listed under criterion C1 in Downs (2015). To be listed under criterion C1 there has to be a high level of confidence in trend data, as the rate of decline must be observed, estimated or projected. Such a high level of confidence would require strong data to back up a listing. While Downs (2015) does present an ‘estimate’ of a potential future continuing decline this figure would far more likely be classed as a ‘suspected’ decline based on the Trend Justification; especially as the species has remained stable despite the current threats it is facing. Therefore, it would appear inappropriate to use this criterion to assess the species.

Given the current trend the species would not approach the threshold for Vulnerable under criteria A2+4 (decline over the past 3 generations, and a decline over 3 generations incorporating the past and the future), and the range of the species is too large for it to approach the threshold for Vulnerable under criterion B. Given that the current population trend is stable, it is also suggested that the species should not be listed as threatened under criterion C. The species could qualify as Vulnerable under criterion D1 though, as the potential population size range does go below 1,000 mature individuals, though it is at the borderline between Vulnerable and Near Threatened. There is also potential for listing under criterion A3 (decline over future 3 generations). Even though the species is currently stable despite the current threats of habitat loss and trade, there are some threats that are increasing in prevalence, such as disease, that could lead to future declines (see Downs 2015). Downs (2015) does state that the potential decline in the future may be at least 20% over 2 generations [though in the Trend Justification stating 20% over 3 generations], which would roughly equate to a decline of 28.4% over 3 generations (30 years). This would thus approach the threshold for Vulnerable under criterion A3cde, but given that Downs (2015) stated that it could be higher it may meet the threshold for Vulnerable (30% decline). However, there is still much uncertainty regarding this suspected future population decline, and so we request any further information regarding the potential for such a decline in the future noting especially that the population is currently considered stable despite potential threats. In the absence of this information it is proposed that the Cape Parrot be listed as Vulnerable under criterion D1.

 

References

Collar, N. 2017. Brown-necked Parrot (Poicephalus robustus). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/node/54604 on 16 May 2017).

Downs, C. T. 2015. Cape Parrot Poicephalus robustus. Pp. 143-145 in The 2015 Eskom Red Data Book of Birds of South Africa, Lesotho and Swaziland (Eds. Taylor, M. R.; Peacock, F.; Wanless, R. W.). BirdLife South Africa, Johannesburg, South Africa.

Downs, C. T.; Pfeiffer, M.; Hart, L. A. 2014. Fifteen years of annual Cape Parrot Poicephalus robustus censuses: current population trends and conservation contributions. Ostrich 85(3): 273-280.

Downs, C. T.; Singh, P. 2016. 19th Annual Parrot Count – Report on the 2016 Cape Parrot Big Birding Day. Hogsback Times (online: https://hogsbacktimes.files.wordpress.com/2016/08/cpbbd-report-72016.pdf).

Hockey, P. A. R.; Dean, W. R. J.; Ryan, P. G. (eds). 2005. Roberts – Birds of Southern Africa, VIIth ed. The Trustees of the John Voelcker Bird Book Fund, Cape Town.

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4 Responses to Archived 2017 topics: Brown-necked Parrot (Poicephalus robustus) is being split into P. robustus and P. fuscicollis: list P. fuscicollis as Least Concern and P. robustus as Vulnerable?

  1. This is a relevant paper:

    Coetzer WG, Downs CT, Perrin MR, Willows-Munro S (2015) Molecular systematics of the Cape Parrot (Poicephalus robustus): implications for taxonomy and conservation. PloS ONE 10:e0133376-e0133376

  2. Alan Lee says:

    Analysis of Cape Parrot reporting rates (a proxy for abundance) from the SABAP2 project, for the period 2007-2017 reveal a very consistent 25% plus minus c6% per year, with no evidence for change (increasing or decreasing) with time. While other projects point to range declines between SABAP1 and SABAP2, the Eastern Cape and core range of the Cape Parrot is a well known atlasing ‘hole’, so using range declines should be treated with caution to infer population change. Currently, year on year trends suggest little change, in alignment with Cape Parrot Big Birding Day data. The arguments of Westripp above make sense given the evidence. Trend data referred to here available on request.

  3. Philip Hall says:

    P.fuscicolliis has a very small population in central Nigeria south of the Jos Plateau and has not been recorded anywhere else in the country. It is likely to be seriously threatened in NIgeria because of agricultural expansion and hunting pressures but very difficult to have a complete understanding of its overall population status.

  4. Andy Symes (BirdLife) says:

    Preliminary proposals

    Based on available information, our preliminary proposal for the 2017 Red List would be to list:

    Cape Parrot as Vulnerable under criterion D1
    Brown-necked Parrot as Least Concern.

    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.

    Please note that we will then only post final recommended categorisations on forum discussions where these differ from the initial proposal.

    The 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.

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