Calonectris edwardsii 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Procellariiformes Procellariidae

Scientific Name: Calonectris edwardsii (Oustalet, 1883)
Common Name(s):
English Cape Verde Shearwater
Taxonomic Source(s): del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 1: Non-passerines. Lynx Edicions BirdLife International, Barcelona, Spain and Cambridge, UK.
Taxonomic Notes: Calonectris diomedea and C. borealis (del Hoyo and Collar 2014) were previously lumped as C. diomedea following Sibley and Monroe (1990, 1993), which was also formerly lumped with C. edwardsii following Hazevoet (1995), contra Brooke (2004).

Assessment Information [top]

Red List Category & Criteria: Near Threatened ver 3.1
Year Published: 2017
Date Assessed: 2016-10-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Bolton, M., Donald, P., Geraldes, P., González-Solís, J., Hazevoet, C., Militão, T., Paiva, V. & Zango, L.
Facilitator/Compiler(s): Anderson, O., Benstead, P., Ekstrom, J., Moreno, R., Taylor, J.
This species is listed as Near Threatened owing to its moderately small population and range size. The effect of invasive species and artisanal and industrial fisheries on the population is not known, and the species may warrant uplisting to a higher threat category when more data on its population size and trends are acquired.

Previously published Red List assessments:

Geographic Range [top]

Range Description:Calonectris edwardsii is now considered a full species, having been split from Cory's Shearwater C. diomedea two decades ago (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 (in front of Dakar, Senegal), foraging over the shelf and shelf break of the African continent (Paiva et al. 2015). When rearing their chick, birds mostly foraged within their colony surroundings, exploiting shallower areas within the Cape Verde Islands, with very few trips towards the African coast (Paiva et al. 2015). They winter between the Brazil and Falklands current, in front of the coast of southern Brazil and Uruguay (González-Solís et al. 2009).
Countries occurrence:
Brazil; Cape Verde; Mauritania; Morocco; Senegal; Uruguay
Spain (Canary Is.); United States
Additional data:
Continuing decline in area of occupancy (AOO):Unknown
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:24300000
Continuing decline in extent of occurrence (EOO):UnknownExtreme fluctuations in extent of occurrence (EOO):No
Number of Locations:7Continuing decline in number of locations:Unknown
Extreme fluctuations in the number of locations:No
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population: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). 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 that took place on the main breeding colonies until 2009.

Current Population Trend:Decreasing
Additional data:
Number of mature individuals:13800Continuing decline of mature individuals:Unknown
Extreme fluctuations:NoPopulation severely fragmented:No
No. of subpopulations:1Continuing decline in subpopulations:Unknown
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:Yes
No. of individuals in largest subpopulation:100

Habitat and Ecology [top]

Habitat and 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).

Systems:Terrestrial; Marine
Continuing decline in area, extent and/or quality of habitat:No
Generation Length (years):19.3
Movement patterns:Full Migrant
Congregatory:Congregatory (and dispersive)

Threats [top]

Major Threat(s):

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 species may also suffer predation from introduced species, such as cats (Nunes and Hazevoet 2001) and from by-catch in artisanal fisheries close to Cape Verde and industrial fishing close or on to the African shelf. Recent records (2014 to 2016 Biosfera unpubl. data) of chicks being eaten by invasive alien ant species on Raso indicate that this could be a possible threat to the species breeding success. 

Conservation Actions [top]

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 (Nunes and Hazevoet 2001) to control human activities and enforce existing legislation. 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.

Amended [top]

Amended reason: Added countries of occurrence.

Citation: BirdLife International. 2017. Calonectris edwardsii (amended version of 2017 assessment). The IUCN Red List of Threatened Species 2017: e.T22729421A119408872. . Downloaded on 22 July 2018.
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