Balearic Shearwaters are one of the rarest birds in Europe and are one of the two bird species listed as Critically Endangered.
Balearic Shearwaters are rare medium-sized seabirds. They have dark grey upperparts, grey-brown underparts and some birds have buff-white parts on their throats, breasts and bellies. There are ash-grey and white tones under the wings, with dark diagonal bars that vary from bird to bird. The bill is dark, legs and feet are a pinkish colour with dark, scattered markings. Their worn-like plumage is similar to the closely related Manx Shearwater; however, Balearic Shearwaters are larger in size.
Both sexes look similar, with the only difference being that males are generally larger. Juveniles are mostly the same but can be told apart from adults between July and September - from the fresh dark colour of their plumage.
Balearic Shearwater in flight
Balearic Shearwaters are silent birds most of the time, becoming vocal usually only when in colonies. Their call is comprised of two notes with the first being noisy and the second being "clear". It's possible to tell the difference between sexes relatively easily by the call, as females tend to have a harsher sounding call similar to a cackle.
Balearic Shearwater call
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Balearic Shearwater floating on the sea
Balearic Shearwaters feed on smaller fish, such as sardines, sprats, anchovies and squid. Whilst fishing, they will dive down to depths of up to 20 metres and for a duration of up to a minute.
As the name suggests, Balearic Shearwaters are best seen in the Balearic Islands - notably Mallorca - and the south coast of France during their breeding season. Post-breeding, they migrate north to the Bay of Biscay with some birds making it to southern England and sometimes even as far north as Scotland.
Cornwall, Devon, Dorset and West Wales are all usually good places to catch these rare birds between late June and September. After September, birds will start their return to breeding colonies.
Balearic Shearwater taking off
Balearic Shearwaters are mainly spotted off the coast, usually in southern parts of the UK. However, they can still be seen in the North Sea off the east coast of England. Both sexes are alike and juvenile birds have fresher looking plumage, with older birds showing traces of moulting.
Breeding usually starts when they are 3 years old and takes place mainly in the Balearic Islands, in colonies. The nests are made of scattered plant material and located in rock crevices or set back on ledges in caves. Females lay just one egg which requires incubating for around 50 days. After laying, the female will go in search of food which could take her away from the nest for up to two days, so initially, the male will usually undertake the first incubation.
Balearic Shearwater in flight
The average lifespan for a Balearic Shearwater is thought to be around 12 years, with some birds living over 20 years, although little is still known about this.