Habitat selection by terrestrial birds on Pemba Island (Tanzania), with particular reference to six endemic taxa

Abstract

An important proportion of the world's biodiversity is found on oceanic islands. Island endemics frequently have small populations and are known to be sensitive to habitat and community changes, making them prone to extinction. In this paper, we assess the habitat distribution of the terrestrial birds of Pemba, an oceanic island that has been classi®ed has an``Endemic Bird Area''. Most of Pemba has been profoundly altered by human activities and only small patches of natural vegetation remain. However, we found that the six endemic birds (four species and two sub-species) have colonised several of the man-made habitats, including clove plantations and farmland, and remain widespread. Species richness was not reduced in these heavily managed areas when compared to the remnants of tropical forest. Nonetheless, the main strongholds of some endemic species are in habitats which have substantially declined in recent years, and which are likely to be further reduced in area in the medium and long term. For these endemics, particularly the Pemba scops owl (Otus pembaensis), the conversion of areas that were formerly clove plantations to open farmland should be considered a serious threat. #

Habitat selection and population trends in terrestrial bird species of Robinson Crusoe Island: habitat generalists versus forest specialists

“…This ecological strategy had made them becoming similarly successful and widespread on the mainland (Johnson 1965(Johnson , 1967Vergara and Armesto 2009). Endemic birds might increase their population or distribution after anthropogenic habitat change (Catry et al 2000;Trainor 2007). However, this does not appear to be the Bird density (n/ha) case for Robinson Crusoe's endemics because they are forest specialists, showing a clear habitat preference for the relict forests, such as described for most paleo-tropic island birds (Riley 2003).…”

“…Habitat loss and degradation on oceanic islands are key processes leading to population decline of endemic birds and facilitating the spread of invasive bird species (Catry et al 2000;Byers 2002;Soh et al 2006). These detrimental effects lead to progressive replacement of endemics by exotic species resulting in increased biotic homogenization (Castro and Jaksic 2008).…”

The Generation of a Biodiversity Hotspot: Biogeography and Phylogeography of the Western Indian Ocean Islands

“…Pemba differs in being a little further away (about 55 km) and is separated from the continent by a very deep trench, such that it has been isolated at least for some million years (Kingdon 1989). Thus Pemba has several well-known endemics such as the Pemba flying fox (Robinson et al 2010), a Mops bat (Stanley 2008), Pemba scops-owl (Fuchs et al 2008), Pemba white-eye (Vaughan 1929), and four other bird species, or subspecies (Vaughan 1929;Catry et al 2000), a day gecko (Phelsuma parkeri) (Rodder, Hawlitschek, and Glaw 2010), a damselfly (Dijkstra, Clausnitzer, and Martens 2007), and several others. Coastal lizards have unique haplotypes on Pemba, differing from those found on the other islands, and those shared between, Unguja and the Tanzanian coast, which is consistent with relatively long island isolation (Rocha et al 2006).…”

Threatened birds of the Angolan Central Escarpment: distribution and response to habitat change at Kumbira Forest

“…Tree density per plot was calculated by counting all the trees with diameter at breast height (DBH) > 10 cm within a 20 m radius of each sample point. The distances from the observer to the nearest tree (dist1) and the nearest neighbour to this tree (dist2) were recorded to calculate a tree density index, using the formula 1/((dist1+dist2)/2) (Catry et al, 2000).…”