NT
Black-vented Shearwater Puffinus opisthomelas



Taxonomy

Taxonomic source(s)
Brooke, M. de L. 2004. Albatrosses and Petrels Across the World. Oxford University Press, Oxford.
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.

IUCN Red List criteria met and history
Red List criteria met
Critically Endangered Endangered Vulnerable
- - -

Red List history
Year Category Criteria
2022 Near Threatened A2cde; B2b(ii,iii)
2016 Near Threatened A2ce; B2ab(i,ii,iii,v)
2012 Near Threatened A2ce;B2ab(i,ii,iii,v)
2010 Near Threatened A2c,e; B2a+b(i,ii,iii,v)
2008 Near Threatened A2c,e; B2a+b(i,ii,iii,v)
2005 Near Threatened
2004 Near Threatened
2000 Vulnerable
1996 Vulnerable
1994 Vulnerable
1988 Near Threatened
Species attributes

Migratory status full migrant Forest dependency does not normally occur in forest
Land-mass type shelf island
Average mass 408 g
Range

Estimate Data quality
Extent of Occurrence (breeding/resident) 38,400 km2 medium
Extent of Occurrence (non-breeding) 2,500,000 km2 medium
Area of Occupancy (breeding/resident) 504 km2 medium
Severely fragmented? no -
Population
Estimate Data quality Derivation Year of estimate
Population size 200000-299999 mature individuals medium estimated 2016
Population trend stable poor suspected -
Rate of change over the past 10 years/3 generations (longer of the two periods) 24% - - -
Generation length 13.5 years - - -
Number of subpopulations 6 - - -
Percentage of mature individuals in largest subpopulation 95-99% - - -

Population justification: The vast majority of the population (>95%) breeds on Natividad (Keitt 1998). On the San Benito islands, there used to be at least several thousand pairs (B. Tershy and B. Keitt in litt. 1999), but only 250-500 pairs were estimated in 1991 (Everett and Anderson 1991), and during the 2017-2019 breeding season, 121 breeding pairs were estimated (Sánchez et al. 2021a). On Guadalupe, the population was estimated at 2,500 pairs in 1991 (Everett and Anderson 1991), although may now be extirpated here (Sánchez et al. 2021a). In 1927, nesting was reported in Isla Rasa, Gulf of California, but the species is believed to be extirpated from that island by introduced rodents (Velarde et al. 2015). Nesting has been reported again since 2010; however, the size of the nesting population has not been determined (Velarde et al. 2015).
The total population estimated in 1998-1999 was around 80,000 pairs, and therefore 160,000 mature individuals. However, it is likely that the methods used in 1998-99 overestimated the population size, as counts of nests in selected areas were extrapolated to the whole surface of the island used by birds, without considering that there were large areas without any burrows.
In 2016, aerial photography and GIS were used to count the total number of occupied and unoccupied burrows in Natividad Island during the breeding season (Albores-Barajas et al. 2016). The total number of burrows counted, including occupied and abandoned burrows, was 56,400, but with a relatively low occupancy (between 75% and 50% depending on the area). The counts gave a figure of 37,900 (± 8500 SE) breeding pairs, equating to about 75,800 mature individuals. This figure was based on the initial occupancy of burrows in February 2016. Of these initially occupied burrows, 4,500 (about 12%) were later abandoned (Albores-Barajas et al. 2016). During the 2017-2019 breeding season, through further surveys on nest or burrow densities, 118,920 breeding pairs were counted on Natividad (Sánchez et al. 2021a), roughly equating to 238,000 mature individuals. Given the small populations present on other islands off Mexico's Pacific coast, the population is therefore placed in the band 200,000-299,999 mature individuals.


Trend justification: The species declined dramatically in the past owing to predation, in particular by introduced cats. On the principal breeding island, Natividad, there was a 15% decrease in habitat and a 13-20% loss in burrows between 1970 and the mid-1990s, with an estimated population decline of 4% per annum (Keitt 1998). However, eradication of cats from Natividad in 2002-2003 suggests that immediate threats to the species have now been significantly reduced and recruitment to the population may have increased. Nevertheless, the current trend has not been quantified. Although the counts from 2016 are much lower than in 1998-1999, data from 1998-1999 apparently overestimated the population; thus, the data do not seem to be comparable. However, as the eradication of cats from Natividad achieved a 90% reduction in mortality and a rapid recolonisation of cat-free areas (Keitt and Tershy 2003, Keitt et al. 2006), it is tentatively suspected that the population is currently stable or increasing slowly. Nevertheless, due to the species' longevity, the rapid declines of 4% per year in the large majority of the breeding population up until 2002 equate to a reduction of c.24% over the past three generations (40.5 years). Notably, bycatch in fisheries, habitat loss to infrastructure developments and habitat degradation through anthropogenic disturbance and introduced mammals and birds remain ongoing threats, and while their impacts on the population size have not been quantified it is possible that the population is still declining locally.


Country/territory distribution
Country/Territory Presence Origin Resident Breeding visitor Non-breeding visitor Passage migrant
Canada extant vagrant yes
Mexico extant native yes yes
USA extant native yes

Important Bird and Biodiversity Areas (IBA)
Country/Territory IBA Name
Mexico Isla Asunción
Mexico Isla San Roque
Mexico Archipiélago Loreto
Mexico Archipiélago Bahía de los Angeles
Mexico Islas Coronado
Mexico Ensenada de la Paz
Mexico Bahía Magdalena-Almejas
Mexico Isla Natividad
Mexico Isla Cedros
Mexico Islas San Benito
Mexico Área de San Quintín
Mexico Bahía Todos Santos
Mexico Isla San Pedro Mártir
Mexico Bahía e Islas de San Jorge

Habitats & altitude
Habitat (level 1) Habitat (level 2) Importance Occurrence
Caves and Subterranean Habitats (non-aquatic) Caves suitable breeding
Marine Neritic Macroalgal/Kelp suitable non-breeding
Marine Neritic Macroalgal/Kelp suitable breeding
Marine Neritic Pelagic major non-breeding
Marine Neritic Pelagic major breeding
Marine Neritic Seagrass (Submerged) suitable non-breeding
Marine Neritic Seagrass (Submerged) suitable breeding
Marine Neritic Subtidal Loose Rock/pebble/gravel suitable non-breeding
Marine Neritic Subtidal Loose Rock/pebble/gravel suitable breeding
Marine Neritic Subtidal Rock and Rocky Reefs suitable non-breeding
Marine Neritic Subtidal Rock and Rocky Reefs suitable breeding
Marine Neritic Subtidal Sandy suitable non-breeding
Marine Neritic Subtidal Sandy suitable breeding
Marine Neritic Subtidal Sandy-Mud suitable non-breeding
Marine Neritic Subtidal Sandy-Mud suitable breeding
Marine Oceanic Epipelagic (0-200m) major non-breeding
Marine Oceanic Epipelagic (0-200m) major breeding
Marine Oceanic Mesopelagic (200-1000m) major non-breeding
Marine Oceanic Mesopelagic (200-1000m) major breeding
Shrubland Subtropical/Tropical Moist major breeding
Altitude 0 - 100 m Occasional altitudinal limits  

Threats & impact
Threat (level 1) Threat (level 2) Impact and Stresses
Biological resource use Fishing & harvesting aquatic resources - Unintentional effects: (subsistence/small scale) [harvest] Timing Scope Severity Impact
Ongoing Whole (>90%) Slow, Significant Declines Medium Impact: 7
Stresses
Species mortality
Human intrusions & disturbance Recreational activities Timing Scope Severity Impact
Ongoing Minority (<50%) Negligible declines Low Impact: 4
Stresses
Species disturbance, Ecosystem degradation
Human intrusions & disturbance Work & other activities Timing Scope Severity Impact
Ongoing Minority (<50%) Negligible declines Low Impact: 4
Stresses
Species disturbance
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Canis familiaris Timing Scope Severity Impact
Ongoing Minority (<50%) Negligible declines Low Impact: 4
Stresses
Species mortality
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Capra hircus Timing Scope Severity Impact
Past, Unlikely to Return Whole (>90%) Slow, Significant Declines Past Impact
Stresses
Ecosystem degradation
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Equus asinus Timing Scope Severity Impact
Past, Unlikely to Return Whole (>90%) Slow, Significant Declines Past Impact
Stresses
Ecosystem degradation
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Felis catus Timing Scope Severity Impact
Past, Unlikely to Return Majority (50-90%) Rapid Declines Past Impact
Stresses
Species mortality
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Oryctolagus cuniculus Timing Scope Severity Impact
Past, Unlikely to Return Whole (>90%) Slow, Significant Declines Past Impact
Stresses
Ecosystem degradation
Invasive and other problematic species, genes & diseases Invasive non-native/alien species/diseases - Ovis aries Timing Scope Severity Impact
Past, Unlikely to Return Whole (>90%) Slow, Significant Declines Past Impact
Stresses
Ecosystem degradation
Invasive and other problematic species, genes & diseases Problematic native species/diseases - Corvus corax Timing Scope Severity Impact
Ongoing Majority (50-90%) Negligible declines Low Impact: 5
Stresses
Species mortality
Invasive and other problematic species, genes & diseases Problematic native species/diseases - Larus occidentalis Timing Scope Severity Impact
Ongoing Majority (50-90%) Negligible declines Low Impact: 5
Stresses
Species mortality
Pollution Excess energy - Light pollution Timing Scope Severity Impact
Ongoing Minority (<50%) Negligible declines Low Impact: 4
Stresses
Species mortality
Residential & commercial development Commercial & industrial areas Timing Scope Severity Impact
Past, Unlikely to Return Majority (50-90%) Rapid Declines Past Impact
Stresses
Species mortality
Residential & commercial development Housing & urban areas Timing Scope Severity Impact
Ongoing Majority (50-90%) Slow, Significant Declines Medium Impact: 6
Stresses
Ecosystem degradation, Ecosystem conversion
Transportation & service corridors Roads & railroads Timing Scope Severity Impact
Past, Likely to Return Minority (<50%) Slow, Significant Declines Past Impact
Stresses
Ecosystem degradation, Ecosystem conversion

Recommended citation
BirdLife International (2024) Species factsheet: Puffinus opisthomelas. Downloaded from https://datazone.birdlife.org/species/factsheet/black-vented-shearwater-puffinus-opisthomelas on 21/02/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from https://datazone.birdlife.org on 21/02/2024.