Yelkouan and Scopoli's Shearwaters belong to the order tubenoses (order Procellariiformes), therefore, are related to one of the largest birds on the Planet - albatroses. Although smaller, they are quite similar in their body shape, flight and life pattern. For a comparison, a wingspan of the largest albatros species is between 2.5 and 3 meters, Yelkouan Shearwater 76 and 89 cm and Scopoli's Shearwater impressive 1.17 and 1.35 meters! They are the only tubenose species nesting in Croatia.
Procelariiformes in Croatian language got their name from tubular structures inside their beaks. Through these tubes, they extract concentrated salty solution which helps them to drink seawater and to be independent of freshwater sources. Procelariiformes (in Latin and English) got their name form Latin word procella – storm.
Procelariiformes are very old group of birds that became a separate group around 60 million years ago. Today, this order includes around 125 bird species, and most of them live in southern hemisphere. Closest relative to these birds are penguins!
Scopoli's Shearwater and Yelkouan Shearwater spend most of their life at the open sea, while only during breeding season they land on islands. They usually come to breading areas during night, which is probably the behaviour developed to avoid predators such as gulls.
Scopoli's Shearwater and Yelkouan Shearwater, as most of the Procelariiformes, historically make colonies on the isolated places, without presence of the mammals, therefore unfortunately, don’t have any defence mechanism developed for protection of nests from mammals that spread there afterwards, like rats, mongoose etc...
... It means that their eggs and chicks are practically helpless before mammals, who in some cases eat the whole colony.
Scopoli's Shearwater and Yelkouan Shearwater reproduce slowly because they lay only one egg per year, and invest lots of care and time for chick’s development. In case they lose the egg or chick, they will not breed another egg that year as some other bird species do.
It takes them a couple of years to gain full sexual maturity (Yelkouan Shearwater more than 3 years, Scopoli's Shearwater more than 5 years), but they also live long, for more than 25 years.
Scopoli's Shearwater (Calonectris diomedea) is thought to be part of the myth about famous hero Diomedes, in which one of the dominant theme was the metamorphosis of his friends after his death...
... The myth is very interesting because it involves navigation routes in the Adriatic, and during recent archaeological excavations on Palagruža Island pottery that suggests Diomedes cult was discovered there...
... The findings also suggest that Palagruža Island is potentially the famous Diomedes’s Island to which the story of his death is related. Apart from geographic position of the island, certain details about birds from that area are in favour of the thesis that the famous hero’s bird is really Scopoli's Shearwater – for their low flight over the sea, for their crying sounds and their close flight to people as well.
Scopoli's Shearwater and Yelkouan Shearwater have very specific calls which they use to communicate with their partners and offspring when they return to their colonies. Because of those creepy sounds during night, fishermen and sailors thought that some islands, like Palagruža Island, were haunted.
Up until recently, Yelkouan Shearwater was considered to be a subspecies of Manx Shearwater (Puffinus puffinus). There is a legend about the Manx Shearwater originating from Njal Saga from Iceland, about events in 11th century...
... it is about the Viking conquest of Dublin, when during three consecutive nights birds in flocks were terrifying Vikings with their calls and were attacking them so they had to defend themselves with swords and shields...
... The Vikings thought the birds were “the Sea Ravens”, but according to their description and locations of breeding colonies, it was clear the birds were actually the Manx Shearwaters. In the end, the Vikings saw this as a bad sign, and they suffered the defeat in their conquest.
