Threats and conservation Over the past five centuries, the combined effects of drought, poor agricultural techniques, the introduction of large numbers of alien herbaceous plant and tree species, the devastating effects of an abundance of goats, and high human population pressure have led to an almost complete destruction of the original vegetation on many of the islands of the Cape Verdes, most arable land now being cleared and planted with maize and beans. Dry woodland and scrub occupy large areas of the arid plains, which have been afforested in the last few decades, but the avifauna of these areas is generally poor. Two of the endemic bird species are considered threatened: Alauda razae on account of its very small population (c.250 birds in 1992) and range, and Acrocephalus brevipennis because of its small and declining population (500 pairs) and range (extinct on two islands probably through drought and associated habitat loss). As a ground-nester, A. razae is extremely vulnerable to the accidental introduction of rats, cats and dogs by fisherman visiting the islet to collect seabirds' eggs and young; a lone dog was seen on Raso in 1994 (C. J. Hazevoet in litt. 1995). Several of the subspecies (see 'Restricted-range species', above) are uncommon, including Ardea (purpurea) bournei (c.25 pairs on Santiago), Milvus (milvus) fasciicauda and Buteo (buteo) bannermani (both rare on Santiago and Santo Antão), and Falco (peregrinus) madens (small numbers on all islands, perhaps fewer than 20 pairs). Pterodroma feae (see 'Restricted-range species') has a population estimated at 500-1,000 pairs and is classified as Vulnerable. It is likely that this species once bred in burrows, but has retreated to mountain ledges after the destruction of the indigenous shrubland. All seabirds have been exploited for centuries on the Cape Verdes and have also suffered from predation by introduced mammals (e.g. cats, rats, green monkeys Cercopithecus aethiops), and as a result there has been a dramatic decline in their populations over the last 100 years. Calonectris (diomedea) edwardsii has suffered in particular, with at least 5,000-6,000 fledglings being collected each year and the likelihood of a disastrous decline within the next few decades (C. J. Hazevoet in litt. 1995). In 1988 a 'National Parks and Protected Areas Programme' (NPPAP) was initiated, including strategies for the conservation of all flora and fauna, and, as a consequence of this, several important seabird islets were declared as nature reserves in 1990, including Raso, Branco, Ilhéus do Rombo, Ilhéu de Curral Velho and Ilhéu de Baluarte (Hazevoet 1994, C. J. Hazevoet in litt. 1995). |
