Data Zone
Justification of Red List category
This species has a very large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km² combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population size may be small, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). The population trend appears to be stable, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). For these reasons the species is evaluated as Least Concern.
Population justification
The most recent population estimate, based on survey counts, is 944 pairs in Namibia and 1,218 pairs in South Africa (A. Makhado in litt. 2021). This equates to a total of 2,162 pairs, or 4,324 mature individuals.
Trend justification
The population is known to fluctuate (Crawford et al. 2012), however the long term trend over three generations is considered to be stable (Crawford et al. 2012; Wetlands International 2021; A. Makhado in litt. 2021).
Microcarbo coronatus is restricted to the southwest coast of southern Africa, where it has bred between Walvis Bay in Namibia and Tsitsikamma National Park in South Africa. In South Africa, numbers in the Northern Cape decreased between 1977–1981 and 2008–2012 and small numbers initiated breeding at colonies to the east of Cape Agulhas at the turn of the century (all breeding had previously been west of Cape Agulhas), but most of the population continues to breed to the west of Cape Agulhas (Whittington 2004, Crawford et al. 2012). The construction of the Bird Rock guano platform in Walvis Bay, Namibia, resulted in a northward range extension of 415 km (Crawford et al. 1994). Breeding in the Tsitsikamma Coastal National Park, extended the species’s breeding range to the east by 355 km (Whittington 2004).
Behaviour This species is largely sedentary, with some movement occurring to the north and east of its breeding range (Crawford et al. 1982). Egg-laying occurs all year round, but with a seasonal peak in late spring and summer - over 60% of nesting activity occurring between November and January (Crawford et al. 1982). At Malgas Island, South Africa, most breeding takes place between September and April (Crawford et al. 1999), while in northern South Africa and southern Namibia, breeding peaks from October to February (Crawford et al. 1999). The seasonal pattern in central Namibia requires investigation (Crawford et al. 1999). The species usually breeds in small groups of 4-50 pairs (del Hoyo et al. 1992, Johnsgard 1993), although colonies supporting up to 280 nests have been recorded (Johnsgard 1993). It usually forages solitarily (Harrison et al. 1997). Habitat The species occurs during both the breeding and the non-breeding season along the coastal cliffs of the mainland and offshore islands in the cold waters of the Benguela Current (del Hoyo et al. 1992). It has never been recorded more than 10 km offshore (del Hoyo et al. 1992), or more than 100 m inland (Johnsgard 1993). It forages in shallow coastal waters and estuaries (Harrison et al. 1997), often in kelp beds (del Hoyo et al. 1992) and among breaking waves or in tidal pools during periods of high tide (Johnsgard 1993). It does not forage off sandy shores (Johnsgard 1993). The Crowned Cormorant is a shallow, benthic forager, diving to a mean depth of 2 m, with a maximum of 18 m (T. Cook unpubl. data). Diet Diet consists largely (97%) (Williams and Cooper 1983) of benthic fish, particularly klipfish (Clinidae) and pipefish (Syngnathidae) of up to 160 mm in length (Williams and Cooper 1983). Shrimps and isopods also form a small part of the diet (Brown et al. 1982). Gobiidae were important in the diet at three colonies located in a lagoon (Crawford et al. 2012). Breeding site This species commonly breeds in mixed seabird colonies. Nest sites include sheltered areas on rocks, cliffs, bushes, small trees, and kelp wracks, as well as man-made structures including jetties, old buildings, the supports of guano platforms, wrecked ships and sometimes moored ships (Nelson 2005). The nest is constructed mostly from kelp and sticks, lined with finer material, and they are often used for several years in succession (Brown et al. 1982). A clutch usually consists of two or three eggs (but occasionally of up to five) (Williams and Cooper 1983), typically producing two chicks, normally from the first two eggs laid (Williams and Cooper 1983). After leaving the nest, chicks form crèches near the colony.
Human disturbance may pose a significant threat to the species (Orta et al. 2020). In a meta-analysis, Carney and Sydeman (1999) showed that most seabird species are negatively affected by human disturbance. Chicks may be crushed as adults are flushed from the nest, and temporary or permanent abandonment of nests leaves nestlings vulnerable to predation. Harrison et al. (1997) found this species to be particularly susceptible to human disturbance.
Invasive Cape Fur Seal Arctocephalus pusillus and Great White Pelican Pelecanus onocrotalus pose substantial threats to the species. Predation by Cape Fur Seals, particularly on fledglings, has escalated due to increases in seal in the Benguela ecosystem following the protection of the seal (David et al. 2003). Out of 13 carcasses found on Dyer Island, 69% displayed wounds identified as inflicted by Cape Fur Seals (Johnson et al. 2006). Pelican predation on seabirds has intensified in recent years (de Ponte Machado 2007, Mwema et al. 2010). During the 2005/06 and 2006/07 breeding seasons, Great White Pelicans depredated all the Crowned Cormorant nests in the lighthouse colony on Dassen Island (one of South Africa’s largest colonies), accountable for more than 200 nests each year and 13% of the national population in 2006/07 (de Ponte Machado 2007, Mwema et al. 2010). In the same year (2006), breeding success was reduced from the normal 1.3 to 0.08 fledglings per nest (Mwema et al. 2010). These observations demonstrate that the species is highly vulnerable to pelican predation.
Mortality due to entanglement in fishing-gear and other man-made materials is another concern (T. Dodman in litt. 2000, J. Kemper pers. obs.). Cormorants are notorious for picking up floating debris to use as nesting material, exposing both adults and chicks to the risk of entanglement and death from starvation. Mortality associated with this type of pollution appears to be low, but few systematic studies have been conducted. All indications are that the amount of debris and number of incidences have increased substantially (Tasker et al. 2000) and hence may constitute a threat of increasing severity in the future.
The 2000 Treasure oil spill caused some mortality of the species, (Crawford et al. 2000).
Conservation Actions Underway
Colonies at Mercury, Ichaboe, Lüderitz Bay and Possession Islands are part of the Namibian Islands’ Marine Protected Area, while those at Sperrgebiet, Bird Island (Lambert’s Bay), West Coast National Park/Saldanha Bay Islands, Dassen Island and Robben Island are fully protected (Barnes 1998). Management practices at breeding islands currently minimise disturbance. Selective culling of Cape fur seals that are observed killing seabirds has occurred since 1993. This has an immediate but short-term effect on seabird mortality rates (David et al. 2003).
Conservation Actions Proposed
A special effort should be made to monitor the population through regular and simultaneous range-wide surveys. Ensure full protection of all breeding colonies (del Hoyo et al. 1992) and ensure that adequate breeding habitat (interestingly, trees are favoured by Crowned Cormorants) is available. Reduce the prevalence of discarded fishing-line and other plastics that pose an entanglement threat. Enforce measures to prevent and mitigate oil-spills. Protect hard-bottom, inshore waters, particularly kelp beds.
Text account compilers
Clark, J.
Contributors
Anderson, O., Ashpole, J, Cook, T., Crawford, R.J.M., Dodman, T., Fjagesund, T., Kemper, J., Makhado, A., Martin, R., Miller, E., Moreno, R., O'Brien, A., Pilgrim, J., Robertson, P., Ryan, P.G. & Taylor, J.
Recommended citation
BirdLife International (2024) Species factsheet: Crowned Cormorant Microcarbo coronatus. Downloaded from
https://datazone.birdlife.org/species/factsheet/crowned-cormorant-microcarbo-coronatus on 23/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 23/12/2024.