THE BIRDS OF THE CAPE VERDE ISLANDS

SUMMARY. Three islands were visited at the start of the rains of 1951. Details of an undescribed collection made by the ‘Blossom’ expedition of 1923–24 are included in this account. The north‐eastern islands are flat and arid, those of the south and west mountainous with more rainfall on the windward slopes. The main habitats include salt‐pans and lagoons, desert, scrub, fields, coffee plantations, tropical irrigation, ravines and towns. There are large sea‐bird colonies exploiting an area of upwelling, rich in food, off the African coast. Thirty land‐birds and ten sea‐birds include relict temperate Palaearctic species established during the Pleistocene and more recent tropical species. The local populations are small, dark, tame and unusually abundant. They differ from those of Europe in feeding habits, habitat preferences, breeding‐seasons, small clutch‐sizes, high nest‐sites, the pitch of voice and appearance. Similar variations occur in Portugal and other Atlantic Islands, and in different islands of the group. In some species changes of form, habitat preference, or feeding‐habits can be correlated with changes in the local environment or the incidence of inter‐specilie competition for food. The warblers of the islands may nest high in trees as a result of a change in the incidence of predation. The rains occur in August, September and October. All the small birds, including Palaearctic species which normally nest in the northern spring, breed at this time. They normally fail to breed in the absence of rain; one Palaearctic species has nested in the spring when the normal rains failed. The scavengers nest after the rains; the water‐birds in the dry season; the desert species and inshore sea‐birds have prolonged breeding seasons with seasonal changes in clutch‐size. The pelagic sea‐birds breed early in the year when there is an increase in the food‐supply off the African coast. The petrels may avoid competition for food by breeding at different seasons. The clutch‐sizes of the islands are unusually small. This may be a consequence of a shortage of food. An annotated systematic list of the birds reported from the group is included.