Rationale
(Changed due to Revised criteria)
The regional population of the near-endemic Bank Cormorant Phalacrocorax neglectus satisfies the population size decrease criterion A2 for Endangered (an observed, estimated, inferred, or suspected decrease in population size of =50% over the past three generations, where the reduction or its causes may not have ceased or may not be understood or may not be reversible). In addition, it is suspected that this decline will continue into the future satisfying criteria A3 and A4.
Distribution
The species is near-endemic to the region, being restricted to the cold waters of the Benguela Current off the West Coast of South Africa and Namibia. It breeds at 45 different locations from Hoanib River mouth, Namibia, to Quoin Rock, South Africa (Crawford and Cooper 2005). Colonies of Bank Cormorants are present at five Important Bird Areas (IBAs) in the region, namely Dassen Island, Dyer Island Nature Reserve, Overstrand, Robben Island National Heritage Monument, and West Coast National Park and Saldanha Bay Islands.
Population
The global population was estimated to be c. 5 600 mature individuals (BirdLife International 2014) while Crawford et al. (2012) estimated the regional population at c. 470 pairs (1 410-1 880 individuals). Confidence in the regional population estimate is high.
Population trend
In 1978, the regional population was 1 506 pairs, equating to 4 518-6 024 mature individuals (Cooper 1981), decreasing by 68.8% to 470 pairs (or 1 410-1 880 mature individuals) in 2011. Counts were incomplete in 1989, but between 1990 and 2011 (22 years, i.e. 3 generations before 2011), the population decreased by 56.9% at the eight main breeding islands. To account for short-term, natural, inter-annual variation in numbers, counts for 1991 were calculated as the average over a 3-year period (1990-1992: 551 pairs) and bird counts for 2011 were also calculated as the average over a 3-year period (2009-2011: 244 pairs; Crawford et al. 2012). Confidence in the regional population trend is high.
Threats
The species is vulnerable to oiling, as it depends on the inshore zone and forests of kelp beds to forage, and these are often directly affected by oil spills. In addition to oiling, it is sensitive to human disturbance and will abandon its nest when approached, leaving the contents to be depredated by Kelp Gulls Larus dominicanus (Cooper 1987). Bank Cormorants could be limited by the availability of nesting habitat and may be out-competed by Cape Fur Seals Arctocephalus pusillus who use the same type of habitat for hauling out or breeding (Crawford et al. 1999).
A link between numbers of breeding pairs at any colony and local estimates of available West Coast Rock Lobster suggests that local reductions in lobster density (either due to human fisheries or environmental forcing, or both) could be driving the decline in the Bank Cormorant population (Crawford et al. 2008a). However, this does not fully explain the decrease, because numbers have continued to decline at colonies inside no-take reserves where lobster is plentiful. In South Africa, Bank Cormorants are winter breeders. Due to their habit of breeding close to shorelines, their breeding success can be negatively affected by large winter storms, which can wipe out nests (Sherley et al. 2012). An increase in frequency and amplitude of these events due to climate change, would have a strong impact on future breeding success of Bank Cormorants. Similarly, Bank Cormorant chicks are suspected to be highly sensitive to heat waves (higher mortality) and such events may be set to increase, owing to climate change (Sherley et al. 2012). An increase in rainfall would also increase chick mortality through flooding of nests or hypothermia.
Conservation
Underway
The species is protected in terms of the Sea Birds and Seals Protection Act No. 46 of 1973. Current conservation actions involve only full protection of breeding colonies of Bank Cormorants, i.e. mainly islands, which fall under the jurisdiction of South African National Parks, CapeNature, and Robben Island Nature Reserve, as well as the mainland colony at Betty's Bay which is managed jointly by CapeNature and Overstrand Municipality. The capacity to hand-rear Bank Cormorants from eggs is being developed by Southern African Foundation for the Conservation of Coastal Birds, in case the population needs to be bolstered in future.
Proposed
A Population and Habitat Viability Assessment (PHVA) is recommended, as is a Biodiversity Management Plan, culminating in a National Species Recovery Plan. In the eventuality that rock lobster is shown to be a primary driver of population dynamics, full protection of rock lobsters should be considered around every island or mainland colony where Bank Cormorants breed. Efforts should be made to census the entire South African population annually so that trends can be assessed more accurately. Increased public awareness of the conservation problems facing this species is needed, particularly in terms of its sensitivity to human disturbance and reliance on rock lobsters for food. Efforts to reduce illegal cleaning of oil tanks at sea and to ensure complete salvage of oil from ships wrecked around breeding colonies would benefit this species (BirdLife International 2014). Bank Cormorants can breed successfully on man-made structures (Sherley et al. 2012) and providing additional, protected, artificial breeding opportunities may be necessary in the future. The ease of human access to nests at Robben Island is a concern and such disturbance almost certainly causes breeding failures. Immediate action to prevent what is technically illegal access should be taken by the Robben Island Museum authorities.
Research
Research is under way at Percy FitzPatrick Institute of African Ornithology and the Animal Demography Unit. This involves mainly the testing of the food-shortage and heat-stress hypotheses for the decline of Bank Cormorant numbers. Abundance of West Coast Rock Lobster Jasus lalandii, a prey animal identified as an important component of Bank Cormorant diet, is suspected to drive part of the population dynamics in South Africa. A modelling approach (using bird counts on the one hand and biomass estimates of rock lobster on the other; both provided by Ocean and Coasts, Department of Environmental Affairs) will test this hypothesis. The hypothesis that global climate change and heat-stress are aggravating factors in the decline is also being tested through a series of field experiments using cameras and temperature loggers deployed in the field.
Bank Cormorants are also the focus of ongoing research into regime shifts in the inshore environment being conducted by the Marine Research Institute at University of Cape Town.
* Future research should focus on using a modelling approach that will test a suite of environmental variables (air temperature, sea-surface temperature, rainfall, wind), as well as biological variables, like seal abundance (a potential competitor) or abundance of other benthic organisms (plant or animal).
* Gaining further information on basic demographic parameters, particularly adult and juvenile survival, and how these respond to environmental variability should also be given priority.
