Biodiversity and Conservation in São Tomé and Príncipe
In this next series of blogs we move on from our regional focus to highlight the projects we support to protect some of the world’s most endangered species. This blog describes the extraordinary and endangered avifauna on the African archipelago of São Tomé and Príncipe, and the work carried out by BirdLife International and its partners to engage local people and raise awareness of the value of the islands’ biodiversity, with the long-term objective of empowering local people to become conservation leaders. Synchronicity Earth recognises that as well as being an ethical imperative, the engagement and empowerment of local communities is fundamental to successful species conservation.
São Tomé grosbeak by Clare Shenstone
On first inspection, the São Tomé Grosbeak (Neospiza concolor) might appear drab, maybe even unremarkable. But first impressions can be deceiving. It is in fact one of the most endangered bird species on the planet, and was not sighted for over 100 years between 1890 and 1991, when it was rediscovered in the forests bordering Rio Xufexufe in the south-west of São Tomé (1). Sightings of this finch since its rediscovery have been intermittent – the species was only photographed for the first time in 2006 and to date has still only been seen by a handful of non-Santomeans. The IUCN Red List of Threatened Species® estimates a tiny extant population of less than 50 individuals (2).
As well as its rarity, the taxonomy of this species is also fascinating and distinct. The São Tomé Grosbeak may be almost unique amongst bird species in that genetic studies suggests it evolved in sympatry with the Príncipe Seedeater, another endemic species (3). Sympatric speciation occurs where two separate species evolve from a common ancestor in the absence of geographic isolation. This could happen if, for example, environmental conditions heavily favoured large individuals and small individuals, but not medium-sized ones, thus driving the evolution of two differently-sized species. The São Tomé Grosbeak is in fact the world’s largest canary with a ‘bullish’ head and powerful bill which rivals that of a Hawfinch – it dwarfs the Príncipe Seedeater and is almost twice its size (4), however questions still remain over what exactly drove the separation of these two species (3).
In fact if there is something unremarkable about the São Tomé Grosbeak it is that it inhabits an archipelago awash with other astonishing flora and fauna. São Tomé and Príncipe are located approximately 250km off the coast of Gabon, and as such have experienced somewhat of a ‘goldilocks effect’, in that they are close enough to the rich tropical forests of West Africa to allow some populations to reach the islands, but distant enough so that once they do these populations become isolated and follow a distinct evolutionary trajectory (5).
Including the São Tomé Grosbeak there are a total of 28 endemic bird species on the islands, meaning a greater number of endemic species than the Galapagos Islands in an area approximately an eighth of the size (6). Amongst these species are the world’s largest Sunbird (Dreptes thomensis), Weaver (Ploecus grandis) and Oriole (Oriolus crassirostris), and its smallest Ibis (Bostrychia bocagei), a species which is also critically endangered and restricted to the primary forests of Obo Natural Park (5). This tendency towards extremes is symptomatic of island biogeography – which encourages small species to become larger to occupy new ecological niches in the absence of competitors and large species to become smaller to survive in a more restricted area (5).
As well as endemic avifauna, the islands also harbour 1,230 described plant species, approximately 15% of which are endemic, as well as 19 endemic butterflies (7). The islands even hold 7 endemic amphibians (7), something which remains somewhat of a mystery considering amphibians known intolerance of salt water and the fact that as volcanic islands São Tomé and Príncipe were never connected to mainland Africa. There are also undoubtedly more discoveries to be made, with the invertebrate and marine biodiversity of the archipelago particularly understudied, with each new expedition to the islands uncovering species new to science (see 8).
The value of the biodiversity present on these islands has been recognised through a number of designations: Príncipe is recognised as a UNESCO Biosphere Reserve; both islands host KBAs and IBAs where primary habitats remain; the Tinhosas Islands to the southwest of Príncipe, which are host to more than 280,000 breeding seabirds, are recognised as a Ramsar site, and the presence and critically endangered nature of the São Tomé Grosbeak, the São Tomé Fiscal, and the Dwarf Olive Ibis triggered the recognition of Obo Natural Park as an Alliance for Zero Extinction site (9). These designations all point to the importance of conserving this archipelago’s remarkable biodiversity, however, historical habitat loss, in parallel with other threats, has driven many of the islands’ species towards extinction. Habitat destruction was rife during the Portuguese colonial era, with the island first a centre for sugarcane production, and latterly coffee and cacao (10). Whilst this led to widespread forest clearance, the primary, secondary and even shade forests on the island continue to provide key habitats, but face new threats in the form of illegal logging, agro-industrial concessions and residential and commercial developments (9).
However, one particular threat which continues to hamper efforts to conserve biodiversity is a lack of local conservation capacity and community engagement. This is something which Synchronicity Earth has partnered with BirdLife International to address, recognising that conservation begins with local people.
BirdLife has had a presence on São Tomé since 2006, with the conservation of the three critically endangered endemic bird species a key focus, culminating in the production of a species action plan (11) produced in collaboration with the Santomean Government and local NGOs. One key pillar of BirdLife’s work has focused on developing the capacity of civil society and raising awareness amongst the local population of the unique and threatened status of São Tomé’s biodiversity. Studies such as that conducted by Verissimo et al., (2012) have shown the low level of environmental education in São Tomé, particularly amongst rural populations. To try to instil an awareness and sense of pride