A review of the Santiago Purple Heron Ardea purpurea bournei, with a report of a new colony

Abstract

SummaryThe Santiago Purple Heron Ardea (purpurea) bournei is endemic to the island of Santiago, Cape Verde Islands. In contrast to nominate purpurea, it nests high in the crowns of large trees. During the 1950s and 1960s, the total population was probably c. 75 pairs, mainly at the now defunct heronry at São Domingos. After the disappearance of that colony during the early 1970s, the only known nesting site was at Boa Entrada, Santa Catarina region, comprising less than 10 pairs. In January 1991, a new colony was discovered at Banana, Ribeira Montanha, with c. 20 recently used nests of which 2–3 had large young in January–February. The current population is thought not to exceed c. 20 pairs. Breeding occurs from late August to March. Apart from two old records in April, there are no records from the non-breeding season. Probably the birds disperse into the mountainous interior of the island after breeding and feed on the dry hillsides. The causes of the decline are unclear, but scarcity of suitable nest-sites and deteriorating climatic conditions may be significant. Because of the extremely small population, the birds and their nesting sites must be protected by law and the local people informed about the birds and their need for protection; educational materials are being developed.