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This regional population of Pink-backed Pelican Pelecanus rufescens numbers less than 1 000 mature individuals, thus satisfying criterion D2 as regionally Vulnerable.
The Pink-backed Pelican has a wide Afrotropical range and also extends to Arabia (Brown et al. 1982), the Seychelles (Stoddart 1977) and Madagascar (Langrand 1990). Two core populations exist in southern Africa: the wetlands of Caprivi, Namibia over to the Okavango-Chobe system in Botswana; and secondly, the coastal plain of southern Mozambique and northern KwaZulu-Natal, south to Durban (Williams and Borello 1997). Historically a colony existed at the mouth of the Hluhluwe River, Lake St Lucia but moved to nearby Nsumo Pan in Mkuze Game Reserve. The species has also bred at Richards Bay (1975-76) and Pongolapoort Dam, Pongola (1975, 1986) (Berruti 1980, Tarboton et al. 1987). Recently, a small colony has been established at Durban Botanical Gardens (Bowker et al. 2010). Birds undertake seasonal movements with CWAC counts indicating that Nsumo and Nyamithi pans are preferred in summer while Lake St Lucia is utilised in winter (Bowker et al. 2010). In addition, regional movements have been recorded with birds from KwaZulu-Natal moving north into Mozambique (Brooke 1981). Although Parker (1999) described the species as an uncommon visitor to southern Mozambique, up to 400 birds have been recorded at different sites in that country. Records from Northern Cape, North West and Gauteng provinces are attributed to birds originating from colonies in the Caprivi/Okavango area (Williams and Borello 1997).
The global population is estimated at 50 000-100 000 birds (Dodman and Diagana 2006). A number of regional estimates have been provided although there are several problems related to obtaining accurate population estimates: the species is long-lived, undertakes seasonal as well as regional movements, and breeds asynchronously (Burke and Brown 1970) with the breeding season lasting more than six months. Williams and Borello (1997) provide an estimate of 250 pairs while Taylor (2000) placed the regional population at 240-300 birds. Estimates of total numbers during summer counts varied from 34 birds (1999) to 250 (2003) with an average of 122 ± 69 (n=14); winter totals ranged from 46 (2003) to 168 (1998) with an average of 82 ± 40 (n=14) (Bowker et al. 2010). More recent counts conducted in October 2004, January 2005 and July 2005 in KwaZulu-Natal produced totals of 46, 628 and 159 (average 278) birds respectively (Bowker et al. 2010), demonstrating the occurrence of extreme fluctuations that take place. Monthly aerial counts for Lake St Lucia, Nsumo and Muzi pans ranged from zero to a maximum of 622 birds (Bowker et al. 2010). In 2010, a colony was reported from at Nyamithi Pan, Ndumo Game Reserve, with no apparent reductions in the size of the nearby Nsumo colony pointing to an apparent increase in the regional population. Based upon this, a regional population of 600-900 mature individuals is estimated (Bowker et al. 2010). However, taking into account that this species is extremely mobile and that numbers fluctuate greatly, the confidence in this regional population estimate is medium.
The global population is perceived to be stable in the absence of any observed declines or substantial threats (BirdLife International 2014). The regional population is likewise considered to be stable, or increasing. Confidence in this trend estimate is medium.
Three sites are of extreme importance to the regional Pink-backed Pelican population, namely Nsumo and Nyamithi pans for breeding purposes in summer, as well as Lake St Lucia for foraging in winter (Bowker et al. 2010). Major threats to the species would be linked to any form of disturbance at these sites. Changes to the natural flooding regimes of pans in the Pongola River Floodplain and the loss of other habitat continually threatens the survival of the species in the region. Colonial nest sites are usually established in tall trees at large waterbodies, in areas that are free from human disturbance. The present sites are in protected areas. However, the birds change sites as the trees in which the nests are built become unsuitable after a few years (Bowker and Downs 2008). Elephants Loxodonta africana also impact on these trees, and the demand for many large and suitable trees around these waterbodies is a potentially limiting factor. As in other piscivores, pelicans are prone to accumulation of toxins in their body tissues, which may impact upon reproductive success.
This species has been the subject of research for the past eight years, and monitoring of breeding colonies continues.
Monitoring of the breeding colony should continue to ascertain trends in population numbers. The small number of breeding sites make the species susceptible to natural catastrophes and breeding failure. Pink-backed Pelicans have attempted to breed in heronries outside of their normal range, and the possibility of enticing the establishment of such additional breeding sites, through planting or modifying of suitable nesting trees, or provisioning of artificial nesting platforms should be investigated (Taylor 2000). Potential sites for such initiatives may include Kruger National Park, Vaal Dam and Barberspan Bird Sanctuary. Otherwise, conservation efforts should focus on maintaining healthy aquatic ecosystems and minimising disturbance at breeding colonies.
* Research into the requirements for breeding and feeding should be conducted to evaluate the feasibility of establishing additional breeding colonies.
* Assessing the nature and scale of elephant impacts on nesting trees is required before remedial or management actions can be recommended.
* The effects of organochlorine and heavy metal toxins on breeding success and fitness should be investigated.