Neil Calbrade

A large shearwater present in the Mediterranean Sea, the Atlantic Ocean, dispersing in the Indian Ocean too. Now largely recognized as two distinct species: Cory’s Shearwater C. borealis, from the East Atlantic Ocean, breeding from Berlengas (off Portugal), Canary Islands to Madeira and the Azores; and Scopoli’s Shearwater C. diomedea, breeding in the Mediterranean Sea, with a few pairs on the Atlantic coast of France.

Season of assessment

B

Population trendUnknown
Population size
(min-max, best estimate)		57000-94300,72800
Red List categoryLC
Franks, S., Fiedler, W., Arizaga, J., Jiguet, F., Nikolov, B., van der Jeugd, Ambrosini, R, Aizpurua, O., Bairlein, F., Clark, J., Fattorini, N, Hammond, M., Higgins, D, Levering, H., Skellorn, W., Spina, F, Thorup, K. Walker, J., Woodward, I. and Baillie, S.R. (1) (2022) Online Atlas of the movements of European bird populations. https://migrationatlas.org EURING/CMS (1) Principal investigator
Map

Overall Connectivity for Cory's Shearwater

The recovery records illustrate the Atlantic dispersion of Mediterranean diomedea, reaching the Gulf of Guinea and Angola. Most recoveries of diomedea are however obtained within the Mediterranean Sea. Recoveries also illustrate the dispersion of borealis to North American and Brazilian coasts, with even one recovery in South Africa. The recovery patterns are driven by the ringing efforts on some breeding colonies, and dead casualties of e.g. beach wrecks of mortality associated with fishing activities, so it might illustrate where birds die, along coasts, and not where they globally disperse. However, the obtained pattern is quite similar to what we would expect given the overall range of the two species. Tracking data of diomedea indicate that adults winter mainly off Senegal and the western Gulf of Guinea (Ristow et al. 2000). Tracked borealis invest similarly the Atlantic Ocean, from Wrest Africa to Brazil (Ramos et al. 2019).

Recoveries by Condition for Cory's Shearwater

Birds recovered between different breeding colonies are alive, but long-distant recoveries concern individuals found dead. Numerically, these dead recoveries represent almost nothing compared to the huge amount of live recoveries on breeding colonies.

Annual Movements for Cory's Shearwater

The recoveries of ringed shearwaters neat the Straits of Gibraltar are from October and November, so diomedea outing the Mediterranean basin probably do so at the end of the breeding season, with juveniles reaching the Atlantic. Observations in the Indian Ocean, and further North in the Red Sea, indicate that some birds perform a clockwise migration around Africa to re-enter the Mediterranean Sea by flying over land in the Middle East. Tracked diomedea from Greece (Ristow et al. 2000) left the Mediterranean by early December, to reach the eastern tropical Atlantic in January/February, the Mid-Atlantic Ridge (even in equatorial waters); they started their return migration in March/April.

Connectivity by Month by Region for Cory's Shearwater

Distant recoveries have been obtained at various months and seasons, so represent the non-breeding dispersion of immatures rather than yearly seasonal movements. For diomedea, within Mediterranean recoveries away from the breeding colonies are mainly from the autumn in the Gulf of Lion, off France, and the western Mediterranean (October-November). For borealis, recoveries off northern Brazil are from June-July, those from southern Brazil are from January to May.

Frédéric Jiguet

References

Statistics Map
N records N individuals N recoveries
Mapped data*
Total available data
*Mapped data include only distant (>= 50 km) recoveries
References Map
Ramos, R., Morera-Pujol, V., Cruz-Flores, M., López-Souto, S., Brothers, M., González-Solís, J.2019 . A geolocator-tagged fledgling provides first evidence on juvenile movements of Cory’s Shearwater Calonectris borealis. Bird Study 66 Link to Article (DOI: https://doi.org/10.1080/00063657.2019.1638341) : 283–288
Ristow, D., Berthold, P., Hashmi, D., Querner, U.2000 . Satellite Tracking of Cory's Shearwater Migration. The Condor 102 Link to Article (DOI: https://doi.org/10.1093/condor/102.3.696) : 696–699

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