| Summary: | Land-based counts at Cabo Carvoeiro (Peniche, Portugal), made between 15 August and 15 November 2015 (effort 90 d, 517 h), tallied302 469 birds, most of which (99.98%) were southbound. Although 65 species were observed, four species contributed to 91% of the total:207 608 Northern Gannet Morus bassanus, 32281 Cory’s Shearwater Calonectris borealis, 16086 Manx Shearwater Puffinus puffinus,and 15 222 Balearic Shearwater Puffinus mauretanicus. Passage as a whole increased throughout the period, mainly due to a gradualintensification of Northern Gannet migration. More than 67 000 southbound procellariforms of 12 species were recorded, as were 6183Stercorariidae of four species. Daily passage rates of species recorded on more than 68 d were positively correlated in 22 of 36 cases.For Northern Gannet and Mediterranean Gull Ichthyaetus melanocephalus, the proportion of adult birds increased steadily, outnumberingyounger birds. Extrapolation based on counted versus uncounted daylight hours suggests that at least 415000 Northern Gannets, 65000Cory’s Shearwaters, and 30000 Balearic Shearwaters passed south at Cabo Carvoeiro in autumn 2015. Clearly, a very large share of theglobal population of the endangered Balearic Shearwater can be monitored at Cabo Carvoeiro. Based on generally unidirectional passagepatterns, high species diversity, as well as high season totals and daily passage rates of several species, Cabo Carvoeiro is one of the mostpromising mainland sites in the eastern North Atlantic to monitor a wide range of seabirds.
|
|---|