Crossley’s Ground-thrush (Zoothera crossleyi): downlist to Least Concern?

This discussion was first published as part of the 2013 Red List update, but remains open for comment to enable reassessment in 2014.

BirdLife species factsheet for Crossley’s Ground-thrush

Crossley’s Ground-thrush Zoothera crossleyi is found in south-eastern Nigeria (on the Obudu and Mambilla Plateaux and Gotel Mountains), Cameroon (from Mt Cameroon and the Rumpi Hills in the south-west to Mt Tchabal Mbabo on the Adamawa Plateau [Dowsett-Lemaire and Dowsett 1999]), southern Congo and north-east Democratic Republic of Congo (DRC) (Urban et al. 1997). It is listed as Near Threatened under criterion B1ab(i,ii,iii) because it was thought to have a moderately small range threatened by agricultural encroachment and logging, and was suspected to be in decline owing to on-going habitat destruction and fragmentation (del Hoyo et al. 2005).

However, recent mapping of the species’s range suggests that its Extent of Occurrence (EOO) is larger than previously thought at an estimated 79,000 km2. Thus, it does not appear to approach the IUCN thresholds for Vulnerable under the range size criteria and could warrant downlisting to Least Concern if it is not found to approach any other thresholds for classification as Vulnerable. The population size has not yet been quantified but the species is described as rare to locally fairly common (del Hoyo et al. 2005). Given its relatively large range size, it seems unlikely that this species would have a population size approaching 10,000 mature individuals and so would not qualify as threatened or Near Threatened on population size under the C criterion. If, however, the species has experienced declines over the past three generations or 10 years (whichever is longer), approaching 30%, it may warrant listing as Near Threatened based on population declines under the A criterion of the IUCN Red List.

Comments on the population trends of this species and its proposed downlisting to Least Concern are welcomed.

References:

del Hoyo, J., Elliott, A. and Christie, D. (2005) Handbook of the Birds of the World, vol. 10: Cuckoo-shrikes to Thrushes. Barcelona, Spain: Lynx Edicions.

Dowsett-Lemaire, F. and Dowsett, R. J. (1999) Survey of birds and amphibians on Mt Manenguba, Mt Nlonako, north Bakossi and around Kupe in 1988-99.

Urban, E. K., Fry, C. H. and Keith, S. (1997) The birds of Africa vol. V. London, UK: Academic Press.

Related posts:

  1. Archived 2012-2013 topics: Papyrus Gonolek (Laniarius mufumbiri): downlist to Least Concern?
  2. Archived 2010-2011 topics: São Tomé Thrush (Turdus olivaceofuscus): list as Near Threatened?
  3. Archived 2010-2011 topics: Rufous Fishing-owl (Scotopelia ussheri): downlist to Vulnerable?
  4. Archived 2011-2012 topics: Yellow-casqued Hornbill (Ceratogymna elata) and Brown-cheeked Hornbill (Bycanistes cylindricus): request for information
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3 Responses to Crossley’s Ground-thrush (Zoothera crossleyi): downlist to Least Concern?

  1. Andy Symes says:

    The following comments were received from Françoise Dowsett-Lemaire on 20 August 2013:

    Poliolais lopezi, Phyllastrephus poliocephalus, Andropadus montanus, Zoothera crossleyi: all are proposed for down-listing to “least concern”. This seems unwise as the montane and semi-montane forests of W. Cameroon are under increasing pressure of deforestation for gardens (e.g. Kupe), and especially in recent years for establishing vast Oil Palm plantations. This has encroached upon some of the Bakossi block of forest, for instance; I don’t have time to carry out a full enquiry into this, but BirdLife ought to.

  2. Andy Symes says:

    Preliminary proposals

    Based on available information and comments posted above, our preliminary proposal for the 2014 Red List would be to treat Crossley’s Ground-thrush Zoothera crossleyi as Near Threatened, approaching the threshold for Vulnerable under criterion A3c.

    There is now a period for further comments until the final deadline of 31 March, after which recommended categorisations will be put forward to IUCN.

    The final Red List categories will be published on the BirdLife and IUCN websites in mid-2014, following further checking of information relevant to the assessments by both BirdLife and IUCN.

  3. Andy Symes says:

    Recommended categorisation to be put forward to IUCN

    Following further review, there has been no change to our preliminary proposal for the 2014 Red List status of this species.

    The final categorisation will be published later in 2014, following further checking of information relevant to the assessment by BirdLife and IUCN.

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