Archived 2010-2011 topics: Rufous Fishing-owl (Scotopelia ussheri): downlist to Vulnerable?

Link to BirdLife species factsheet for Rufous Fishing-owl

Rufous Fishing-owl Scotopelia ussheri, an Upper Guinea endemic, is currently listed as Endangered because its population is presumed to be very small (i.e. <2,500 mature individuals) and fragmented into smaller subpopulations, which are seriously threatened by forest loss.

The species is reportedly susceptible to disturbance associated with deforestation and probably the poisoning of streams and rivers, and it may be declining rapidly. Dowsett-Lemaire and Dowsett (2009) report that information to date suggests that this owl is more widespread than previously thought, and this is also true of its status elsewhere, as in Gola Forest in Sierra Leone (pers. obs., Dowsett-Lemaire & Dowsett 2008). It survives in degraded situations provided they are swampy and there is enough cover and is listed from at least twelve locations (Dowsett-Lemaire and Dowsett 2009) and anecdotally by hunters and fishermen when they check their fish traps on small to medium-sized streams or swamps.

While no population estimate exists based upon the collation of available records, the weight of evidence here casts doubt on whether the global population is really likely to number fewer than 2,500 mature individuals. If the population is assumed to be larger than this the species may warrant downlisting to Vulnerable under criterion C2a with a population of not more than 10,000 mature individuals that is continuing to decline. It is important to understand the species’s population structure and whether there is any interbreeding between sub-populations. It is also important to assess the rate of forest clearance and the affect this has had on the species. If population declines inferred from habitat degradation have exceeded 30% over the past three generations (18.4 years based on a generation time of 6.1 years; BirdLife International unpublished data) the species also meets the threshold for listing as Vulnerable under criterion A.

When it was last assessed in 2008 BirdLife International provided a cautionary note that it is very likely the species’s future survival will depend on populations in protected areas, which presently receive inadequate management and protection. Therefore, additional comments on predicted future habitat loss and the nature of existing protection are welcomed.

Dowsett-Lemaire, F. and Dowsett, R. J. (2009) Comments on selected forest reserves in SW Ghana: wildlife and conservation status. A report prepared for the Forestry Commission, Accra, Ghana. Misc Report 64.

(This discussion was first started as part of the 2010 Red List update)

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2 Responses to Archived 2010-2011 topics: Rufous Fishing-owl (Scotopelia ussheri): downlist to Vulnerable?

  1. Andy Symes says:

    Comments received as part of 2010 update:

    Hugo Rainey (December 2009):
    Dowsett-Lemaire and Dowsett (2009) suggest that the Rufous Fishing Owl may be under-reported and can use quite degaded habitat. Previously it has been suggested that it is under-reported as it occurs in more intact habitats which are less often visited as they are can be difficult to access. If this species does indeed use quite degraded habitat and is quite widespread, why have there been so few records of this or any fishing owl in Upper Guinea forests? The loud call can be confused with Pel’s Fishing Owl Scotopelia peli, but even this is not commonly reported in the region. Is the situation in some relatively well-managed forest areas in Sierra Leone and SW Ghana may be somewhat different from those in Cote d’Ivoire and elsewhere? The extent of probable preferred habitat (mangroves, swamp forest, riverine forest, etc.) in the region is quite limited and continues to decline as it is still very threatened by many factors. For example Marahoue NP where I recorded this bird eight years ago has now been cleared of semi-deciduous forest.

    We know virtually nothing about the population structure, density, territory size, etc., of this species. Estimates of the population size are therefore not based on evidence. Rate of change of the population could possibly be estimated from rate of forest cover change. The FAO data suggests a rate of forest loss in Upper Guinea of around 11% from 1990-2005 (which in my opinion appears to be a low rate of loss). This rate is not likely to be reversible. This would be too low a rate of decline (as a result of loss of habitat) for it to be categorised as Vulnerable. The original threat listing status was carried out when the rate of loss of the Upper Guinea forests was much higher during the 1980s. Therefore the threat status may need to be re-evaluated using other criteria. Should it be changed to Data Deficient which is not a helpful category or should it be maintained as Endangered (as ‘A taxon may be moved from a category of higher threat to a category of lower threat if none of the criteria of the higher category has been met for five years or more.’) pending better information about threats and its population?

    Francoise Dowsett-Lemaire (March 2010):
    Having been in the field for several weeks, this is the first chance I have to see your message and text on Rufous Fishing Owl. I see no objection in changing the status of this bird. Further surveys at the end of the year have suggested it is also present in extensive swamp forest in the Amansuri wetlands (this is based on testimony by fishermen and local guides) situated to the south of Ankasa, near the coast. I have obtained further evidence of its presence in Subri Forest Reserve, as it was seen there by Robert Ntakor, excellent ornithologist, in the south-east of the reserve, on a river.

    In the little write-up you have produced, you forgot to include Dowsett-Lemaire & Dowsett 2008 in the references: this is a paper we published in the Bull. ABC on Gola birds.

  2. Hugo Rainey says:

    In addition to my previous comments, it would be interesting to hear from other scientists and birders in the Upper Guinea region who have worked in swamp forest, in streams and rivers and other areas with forest close to streams. If they have worked in such habitats it would be interesting to hear whether or not they have recorded this species – both positive and negative reports are valuable here.

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