P.R. Lowe, 1921
Puffinus puffinus mauretanicus
The Balearic shearwater (Puffinus mauretanicus) is a medium-sized shearwater in the seabird family Procellariidae. It was long regarded a subspecies of the Manx shearwater (see there for more on the Puffinus puffinus superspecies); following an initial split it was held to be a subspecies of the "Mediterranean shearwater" (Sibley & Monroe 1990) for nearly ten more years, until it was resolved to be a distinct species, separate from the yelkouan shearwater (Wink et al. 1993, Heidrich et al. 1998, Sangster et al. 2002). It is the last taxon of the puffinus complex that was recognized as a separate entity.
It appears to belong to a group of Mediterranean and adjacent Atlantic species which includes the yelkouan shearwater (Austin 1996) and one to three prehistorically extinct taxa, Hole's and possibly also Olson's shearwater and an undescribed form of unclear distinctness from Menorca (Alcover 2001). Hole's shearwater may be the closest known relative of P. mauretanicus. The two living Mediterranean lineages had probably separated before the end of the Pliocene (c. 2 mya), as indicated by molecular differences and the Ibizan fossil Puffinus nestori from the Late Pliocene or Early Pleistocene, which may have been the direct ancestor of the present species (Heidrich et al. 1998).
This bird is approximately 33 cm long, with an 85–90 cm wingspan. It has the typically "shearing" flight of the genus, dipping from side to side on stiff wings with few wingbeats, the wingtips almost touching the water. This bird looks like a flying cross, with its wing held at right angles to the body, and it changes from dark brown to dirty white as the dark upperparts and paler undersides are alternately exposed as it travels low over the sea.
Apart from the less contrasted plumage, this species is very similar to the Atlantic Manx shearwater and the yelkouan shearwater found elsewhere in the Mediterranean. There exists at least one mixed breeding colony of Balearic and yelkouan shearwaters, on Minorca, and the species' winter ranges overlap in the Central Mediterranean; for scientific purposes at least, a combination of morphological characteristics and DNA sequence data is suggested to identify the species (Genovart et al. 2005).
It is under severe threat from the development of holiday resorts near its breeding sites, and also from animals such as cats and rats. The discovery of yelkouan shearwaters in the Minorcan colony suggests that hybridization may also pose a problem (Genovart et al. 2005); the Balearic shearwater is considered critically endangered with extinction by the IUCN. Recent models estimate a mean decrease of 7.4% per year and a mean extinction time of 40.4 years. This equates to an ongoing decline of more than 80% over the next three generations (54 years).
This is a gregarious species, which can been seen in large numbers from boats or headlands, especially on in autumn.
It is silent at sea, but at night the breeding colonies are alive with raucous cackling calls, higher pitched than the Manx shearwater's.
- BirdLife International (2013). "Puffinus mauretanicus". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
- Sibley, Charles Gald & Monroe, Burt L. Jr. (1990): Distribution and taxonomy of the birds of the world. Yale University Press, New Haven, CT. ISBN 0-300-04969-2
- Wink, Michael; Heidrich, Petra & Ristow, D. (1993): Genetic evidence for speciation of the Manx shearwater (Puffinus puffinus) and the Mediterranean Shearwater (P. yelkouan). Die Vogelwelt 114(6): 226-232. [Article in English with German abstract] PDF fulltext
- Heidrich, Petra; Amengual, José F. & Wink, Michael (1998): Phylogenetic relationships in Mediterranean and North Atlantic shearwaters (Aves: Procellariidae) based on nucleotide sequences of mtDNA. Biochemical Systematics and Ecology 26(2): 145–170. doi:10.1016/S0305-1978(97)00085-9 PDF fulltext
- Sangster, George; Knox, Alan G.; Helbig, Andreas J. & Parkin, David T. (2002): Taxonomic recommendations for European birds. Ibis 144(1): 153–159. doi:10.1046/j.0019-1019.2001.00026.x PDF fulltext
- Austin, Jeremy J. (1996): Molecular Phylogenetics of Puffinus Shearwaters: Preliminary Evidence from Mitochondrial Cytochrome b Gene Sequences. Molecular Phylogenetics and Evolution 6(1): 77–88. doi:10.1006/mpev.1996.0060 (HTML abstract)
- Alcover, Josep Antoni (2001): Nous avenços en el coneixement dels ocells fòssils de les Balears. Anuari Ornitològic de les Balears 16: 3-13. [Article in Catalan, English abstract] PDF fulltext
- Genovart, Meritxell; Juste, Javier & Oro, Daniel (2005): Two sibling species sympatrically breeding: a new conservation concern for the critically endangered Balearic shearwater. Conservation Genetics 6(4): 601–606. doi:10.1007/s10592-005-9010-z (HTML abstract)
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