EN
Bank Cormorant Phalacrocorax neglectus



Justification

Justification of Red List Category

This species is listed as Endangered since a very rapid decline in its small population has been observed on the breeding grounds as a result of human disturbance, displacement by seals, and food shortages. 

Population justification
The total breeding population was estimated at 2,500 pairs (5,000 mature individuals) in 2015. This roughly equates to 7,500 individuals in total.

Trend justification
The overall rate of decline between 1990 and 2006 was 4.3% per year (Kemper et al. 2007), equivalent to a decrease of 62.8% over three generations (22.5 years).

Distribution and population

Phalacrocorax neglectus is known to breed at 45 localities between Hollambird Island, Namibia, and Quoin Rock, South Africa. Birds in breeding plumage have been sighted as far north as Swakopmund but breeding in this area is yet to be confirmed (M. Boorman pers. comm. to R. B. Sherley in litt. 2016). Approximately 80-90% of the breeding population is located on Mercury (2,019 pairs) and Ichaboe Islands (196 pairs), Namibia (Kemper et al. 2007, Ludynia et al. 2010, Ministry of Fisheries and Marine Resources [MFMR] unpubl. data). The non-breeding range extends from just south of Hoanibmond (Hoanib River Mouth) south to Die Walle. Several island populations in the west and north Cape Province have declined in recent years and seven former breeding localities have been vacated (Harrison et al. 1997). The total number of breeding pairs fell from 7,600 in 1978-1980 to 5,750 by 1990 and to 2,800 by 2006 (Kemper et al. 2007). Between 1993 and 1998, the Namibian breeding population is estimated to have declined by 68%, mainly due to a population collapse on Ichaboe Island after 1994-1995, mainly thought to result from food shortage, but other factors, e.g. predation and displacement by seals may also be a factor (Ludynia et al. 2010). Numbers on Ichaboe have since continued to decline, and although numbers have increased on Mercury Island and are currently stable (Ludynia et al. 2010); the total Namibian population in 2006 was 39% less than in 1993 (Kemper et al. 2007).

  

Ecology

Behaviour  Adults are highly sedentary, and although individuals have been known to move up to 150 km, a mark-recapture survey recovered a large majority of adults within 10 km of the point of banding (Cooper 1981). Juveniles tend to disperse over larger distances, with adults and immatures tending to occur and forage in different areas (Kemper et al. 2007). They are gregarious at colonies, although forage singly or in loose groups of up to 15 birds (del Hoyo et al. 1992, Johnsgard 1993). Breeding activity occurs year round but is concentrated between May and October in the southern and central part of its range, and between November and April in the northern extension of its range (Crawford et al. 1999, MFMR unpubl. data).  Habitat  The distribution of this species broadly reflects that of kelp Ecklonia maxima beds and they are rarely found more than 10 km from shore (Cooper 1981). They do not use estuaries or inland waters (Johnsgard 1993).  Breeding  They breed on sea-cliffs and rocky offshore islands (Nelson 2005), sometimes making use of walls or artificial platforms in close proximity to the sea (Cooper 1981, Sherley et al. 2012). Their large size makes it difficult to take off, and this may influence and limit their choice of habitat (Nelson 2005).  Diet  The species has a varied diet including fish, crustaceans and cephalopods (Williams and Burger 1978, Cooper 1985, Ludynia et al. 2010). Through much of their range they prefer to forage on the sea floor - especially among kelp beds at depths of 5 -15m - and prey mainly on klipfish (Clinidae) and blennies (Blenniidae) associated with the benthic habitat (Williams and Burger 1978). In the northern part of the range, where the largest populations occur, they forage away from the kelp beds and the majority of their diet consists of Bearded Goby Sufflogobius bibarbatus typically foraged around 30-40 m depth (Williams and Burger 1978, Cooper 1981, Ludynia et al. 2010). In the South African part of the range, commercially fished Cape Rock Lobster Jasus lalandi forms an important component of their diet (Cooper 1985, Sherley et al. 2016).  Breeding site  Nests are built on exposed rocks, walls or artificial platforms in close proximity to the sea (Cooper 1981). The nest is very large (up to 6 kg) (Nelson 2005) and is constructed mainly from seaweed species with some sticks and feathers incorporated (Nelson 2005). A clutch consists of one to three eggs, rarely four (R. Jones pers. comm. to R.B. Sherley et al. in litt. 2016), with a mean of two (Cooper 1987), but nests are often lost to rough seas (Sherley et al. 2012). The young leave the nest before they are able to fly properly, and so are particularly vulnerable to predation and disturbance at this stage. Age at first breeding is two to three years and average longevity of breeders is estimated at six years (Crawford et al. 1999, 2001).

Threats

Changes in food availability as a result of commercial fishing is a major threat facing this species. Decreased abundance of Bearded Goby Taenioides jacksoni off the coast of Namibia in 1994 led to population crashes at two major colonies (Mercury and Ichaboe Islands) and extreme food scarcity continues to drive declines (du Toit et al. 2002). Distributional shifts of Cape Rock Lobster Jasus lalandii as a result of lobster fishing caused decreases of larger Bank Cormorant colonies in northern South Africa and increases in the south (Crawford et al. 2008) and continued fishing of this major food source may be contributing to ongoing declines on a national level (Sherley et al. 2016). A further impact of the lobster fishery is incidental bycatch of birds in lobster traps (Cooper 1985).

The species suffers from habitat competition (Crawford et al. 1999) and predation (du Toit et al. 2002) by Cape Fur Seals Arctocephalus pusillus pusillus. In the past, seals at Mercury Island displaced 14% of the global population of Bank Cormorants. The island is now home to 33% of the global population, after seals have been eliminated (du Toit et al. 2002). Kelp Gulls Larus dominicanus and Great White Pelicans Pelecanus onocrotalus also depredate cormorant nests (Kemper et al. 2007). The observation of pelicans in locations where they were previously unrecorded suggest that predation pressures may be intensifying (de Ponte Machado 2007).

Elevated temperatures and increased frequency and amplitude of storms due to climate change, would have a strong impact on future breeding success of Bank Cormorants. Recent nest failures at Robben Island were related to wave heights and air temperature, with reduced chick survival in years when major storm events coincided with the breeding season (Sherley et al. 2012). 73% of the species is classified at risk of exposure to coastal flooding (Crawford 2015).

The species is sensitive to human disturbance when breeding and will abandon nests if approached, leaving the contents vulnerable to predation (Cooper 1987). Between 1978 and 1997, human disturbance resulted in the loss of four colonies, and reductions in the populations at six others (du Toit et al. 2002). Guano mining has contributed to disturbance and habitat loss in the past (Ichaboe Island, 2000) and mining activities are likely to resume in the future (du Toit et al. 2002). Activities related to tourism (sea-kayaking, scuba-diving), organised sport (surf-ski races) and research activities (pellet collection, breeding surveys) pose a threat to the species in parts of its range (du Toit et al. 2002). Commercial development in coastal areas may cause habitat loss through harbour developments, causeways and dredging (du Toit et al. 2002). Although artificial structures, e.g. harbour walls, may provide additional nesting sites, these may represent lower-quality breeding habitat (du Toit et al. 2002, Sherley et al. 2012).

Past oil spills (e.g. Apollo Sea, 1994 and Treasure, 2000) severely affected the species. The Treasure oil spill significantly decimated the population (Crawford et al. 2000, du Toit et al. 2002), but numbers subsequently recovered (Sherley et al. 2012). The impacts of previous spills may still be causing reduced reproductive success in affected individuals, and ongoing chronic pollution is known to be impacting other species in the region (African Penguin Spheniscus demersus) (Crawford et al. 2000).

Avian Cholera has severely affected other cormorant species and the disease is present on islands with breeding colonies of Bank Cormorants. Yet, only a few deaths related to outbreaks have been recorded and the episodes seem to be predominantly single-species mortality events impacting Cape Cormorants Phalacrocorax capensis (Waller and Underhill 2007).

Conservation actions

Conservation Actions Underway
In South Africa, it is protected by law and the terrestrial areas of the major islands where it breeds are national parks, nature reserves or otherwise protected. However, some of the smaller breeding rocks are not protected. Only 11 of the 45 (24%) extant breeding colonies have nature reserve status (Du Toit et al. 2002). The colonies around Saldanha Bay, at Robben Island and at Stony Point are surrounded by at-sea areas of spatial protection, but all are smaller than the foraging range believed to be used by breeding adults (Ludynia et al. 2010, Sherley et al. 2016). In Namibia, all breeding localities and key foraging ranges of breeding birds are included in the Namibian Islands Marine Protected Area (Currie et al. 2009, Ludynia et al. 2012).

Conservation Actions Proposed
Develop and implement management plans to protect breeding islands and cover the effects of human disturbance (Cooper 1981, Du Toit et al. 2002). Protect sites accessible to humans from the mainland at low tide. Census the population regularly so that trends can be assessed. Use colour-banding and biologging to better understand the species movements (Du Toit et al. 2002, Ludynia et al. 2010). Develop and implement a sustainable fisheries plan for the Benguela Upwelling Region to avoid over-depletion of fish and lobster stocks (Du Toit et al. 2002), including a potential ban on lobster fisheries within key areas to reduce the risk of entanglement of benthic diving birds in the traps and competition for decreasing lobster resources (Ludynia et al. 2010, Sherley et al. 2016). Take measures against the illegal cleaning of oil tanks at sea, which causes significant oil spills. Develop a contingency plan for major oil spills off the coast of south-western Africa (Du Toit et al. 2002). Improve the legal protection of Namibian offshore breeding sites (Du Toit et al. 2002). Increase public awareness of the conservation problems facing this species (Du Toit et al. 2002). The species can breed successfully on man-made structures (Sherley et al. 2012) and provision of additional, protected breeding habitat may be necessary in the future.

Identification

76 cm.  Large, matt black-and-brown cormorant lacking bright gular patch.  Adult in nuptials shows varying amounts of white philo-plumes on head and rump.  These quickly vanish after courtship and egg-laying. Bronzed-greenish upperparts with dark edging to mantle and wing-coverts.  Slight erectile crest appears as small bump on forehead.  Juvenile and immature lack bronzing.  Similar spp.  Differs from Cape Cormorant P. capensis by lack of orange gular patch, stouter bill, thicker and less snake-like neck, and broader, deeper head, also brown rather than blue iris.  Voice  Loud wheeee, accompanied by loud foot-slapping on rocks, as male lands in colony.

Acknowledgements

Text account compilers
Robertson, P., Symes, A., Taylor, J., Ekstrom, J., Fjagesund, T., Anderson, O., Ashpole, J, Martin, R., Miller, E., Moreno, R., Pilgrim, J.

Contributors
Simmons, R.E., Ludynia, K., Sherley, R., Kemper, J., Morris, T.L.


Recommended citation
BirdLife International (2019) Species factsheet: Phalacrocorax neglectus. Downloaded from http://www.birdlife.org on 21/09/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 21/09/2019.