NT
Cape Verde Shearwater Calonectris edwardsii



Justification

Justification of Red List Category
This species is listed as Near Threatened owing to its moderately small population and range size. The effect of invasive species as well as of small-scale and industrial fisheries on the population is not known. The species may warrant uplisting to a higher threat category when more data on its population size and trends are acquired.

Population justification
A full island survey during the 2015 breeding season resulted in 6,312 breeding pairs counted on Raso and a further 3,500 birds on Branco (Biosfera unpubl. data). This is equivalent to c.24,000 individuals in total.

Trend justification
The population is suspected to have declined over the past 67.5 years (three generations) owing to uncontrolled levels of harvest, which took place on the main breeding colonies until 2009.

Distribution and population

Calonectris edwardsii has been split from Cory's Shearwater C. diomedea (Bretagnolle and Lequette 1990, Hazevoet 1995, Porter et al. 1997). It is considered locally common in Cape Verde (Hazevoet 1995), with large numbers frequently seen off the island of Raso (P. Donald in litt. 2003, C. Hazevoet in litt. 2003). The largest colonies are on Raso, Branco and Brava. Breeding is sparse on Santiago, São Nicolau and Santo Antão (C. Hazevoet in litt. 2003). The total population has been estimated to number c. 10,000 pairs since 1988-1993 (Hazevoet 1995, Nunes and Hazevoet 2001). Raso and Branco together hold the majority of the population, with 5,000-7,500 pairs estimated in 1988-1993 (Hazevoet 1995). A full island survey during the 2015 breeding season resulted in 6,312 breeding pairs counted on Raso and further 3,500 birds on Branco (Biosfera unpubl. data).
During incubation, birds mostly target a discrete region off West Africa (off Dakar, Senegal), foraging over the shelf and shelf break of the African continent (Paiva et al. 2015). When rearing chicks, birds mostly forage within the surroundings of the colony, exploiting shallower areas within the Cape Verde Islands, with very few trips towards the African coast (Paiva et al. 2015). Individuals winter between the Brazil and Falklands Current, off the coast of southern Brazil and Uruguay (González-Solís et al. 2009).

Ecology

Arriving at colonies in late February to March after an absence of some three months, the birds nest in hollows in cliffs and offshore rocks, and under large boulders (Murphy 1924, Hazevoet 1995). Its diet is composed mostly by Clupeidae (Sardinella maderensis), squid (Loligo sp.) and Carangidae (Selar crumenophthalmus) (Rodrigues 2014).

Threats

The species has been harvested for a long time, mostly on Raso and Branco, probably for several centuries (Murphy 1924, P. Donald in litt. 2003, C. Hazevoet in litt. 2003). Eighty years ago, ornithologists recorded 'boat-loads' of this species being taken by fishermen for consumption (Murphy 1924). In 2001, at least 500 chicks were taken on Raso in a single day (P. Donald in litt. 2003) and the remains of several thousand shearwaters have been found on Branco, which were probably accumulated over many years (C. Hazevoet in litt. 2003). The people behind Biosfera I (Environmental Association based in Cape Verde) have recently been quite successful in preventing the traditional October raids of nestlings of Cape Verde Shearwater on Raso by fishermen from Santo Antão (Hazevoet 2003). The species is also at risk from predation by invasive feral cats Felis catus (Nunes and Hazevoet 2001), bycatch in artisanal fisheries off the coast of Cape Verde as well as in industrial fleets operating on the African shelf.

Conservation actions

Conservation Actions Underway
The species is protected by law and unauthorised entrance to both Raso and Branco is officially illegal, but there is no real control (C. Hazevoet in litt. 2003). In 1991, the government declared Santa Luzia, Branco, Raso, Cima, Curral Velho and Baluarte as natural reserves (Nunes and Hazevoet 2001). However, the regulation of human activities has not been published and no wardening has been put in place (Nunes and Hazevoet 2001).

Conservation Actions Proposed
Re-assess the population size to acquire an up-to-date estimate. Monitor the harvest of the species. Employ wardens in protected areas to control human activities and enforce existing legislation (Nunes and Hazevoet 2001). Carry out an education programme to discourage the consumption of shearwaters (C. Hazevoet in litt. 2003). Promote and encourage the use of other sources of protein.

Acknowledgements

Text account compilers
Taylor, J., Benstead, P., Fjagesund, T., Anderson, O., Hermes, C., Martin, R., Moreno, R., Ekstrom, J., Stuart, A.

Contributors
Zango, L., Bolton, M., Militão, T., González-Solís, J., Paiva, V., Donald, P., Hazevoet, C., Geraldes, P.


Recommended citation
BirdLife International (2021) Species factsheet: Calonectris edwardsii. Downloaded from http://www.birdlife.org on 03/12/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 03/12/2021.