Angola is not generally known as an important birding destination, but this could soon change. The country’s bird population has received a boost with the news that a previously unknown tract of Afromontane forest has been discovered in the southern African country.
Afromontane means “African mountain” and the term describes a type of eco-region, and the plants and animals associated with it, which is found in mountainous regions of Africa and the southern Arabian Peninsula. This type of environment can occur up to an elevation of 2 000m above sea level, or as low as 300m.
It is found mainly on the eastern side of the continent from the Red Sea right down to Knysna’s green abundance in South Africa. In Angola, the montane vegetation consists of grasslands and woodlands, rather than the tropical and subtropical vegetation found further north.
This lush forest environment is important because it’s the most threatened habitat type in the country, and it’s home to some rare bird species.
More forest than previously thought
The new discovery was made in the Namba mountains, by a team of scientists that included ornithologists Martin Mills and Martim Melo of Cape Town's Percy Fitzpatrick Institute of African Ornithology, as well as Portuguese journalist Alexandre Vaz.
The team published their findings in the online June issue of the peer-reviewed Bird Conservation International journal.
The report, written by Mills, Melo and Vaz and titled The Namba mountains: new hope for Afromontane forest birds in Angola, revealed that previously, about 200ha of this vulnerable forest was thought to exist in Angola, 85ha of it located on Mount Moco, the country’s highest peak at 2 620m.
The Namba mountains and nearby Mount Moco are situated in southern Cuanza Sul province, and lie within the Western Angola endemic bird area. This important bird habitat shelters a number of species which are confined to this region, such as the endemic genus Xenocopsychus, which has only one species, the Angola cave chat (X. ansorgei), listed as near threatened.
A group of organisations and individuals, including Mills and Melo, is already involved in a conservation project that involves the Kanjonde community living near Mount Moco.
The initiative aims to educate the community about minimising the impact on the ecosystem; promote sustainable tourism in the area with the community as the main beneficiary; supply the village with fuel-efficient stoves that will cut down on deforestation; and replenish the forest around the mountain by growing trees in a locally-run nursery.
The villagers in charge of the nursery are paid for their services, and in his latest report, filed in February 2012, Mills said that the project was thriving.
The team visited the Namba mountains in July 2010 to survey the bird life and to establish more accurately the extent of the existing forest. They were unable to physically explore the whole area because it was difficult to move around in the densely forested and often boulder-strewn terrain, but they still managed to record 89 bird species.
Fifty-six species were observed in or adjacent to the forest, and included a sizeable population of the endangered Swierstra's francolin (Pternistis swierstrai), an endemic species found near the forest edges.
All 20 species which are generally found in Angolan forests and which are an indicator of the conservation health of the area, such as the Bar-tailed trogon (Apaloderma vittatum), Orange ground thrush (Zoothera gurneyi) and Laura’s woodland warbler (Phylloscopus laurae), were sighted.
“Previously the only site in Angola at which all 20 forest-associated Afromontane taxa had been recorded was Moco,” wrote the team. “However, during brief surveys at the Nambas we found all 20 species, including several species that are now rare or extinct at Moco, many of them common.”
According to the team, it is likely that the Namba region can now claim to hold the largest populations of these 20 species.
Technology to the rescue
Thwarted in their efforts to map the area at ground level, the team turned to Google Earth on their return, using newly available imagery to survey the area from above.
“We used cloud-free, high-resolution images from 2003 available on Google Earth,” wrote the authors in Bird Conservation International. “We traced the perimeter of each forest patch larger than 2.5ha to create a .kml [Google Earth file] polygon file and calculate its perimeter length in kilometres, area in hectares and area/edge ratio.”
The percentage of closed-canopy forest cover, they wrote, within each patch was visually estimated to the nearest 5%, to calculate the amount of forest in each patch.
Out of this further survey, wrote the team, came the conclusion that “the densely vegetated habitat of the Nambas was found to consist of mature, closed-canopy Afromontane forest with the broad-leafed Yellowwood (Podocarpus latifolius) as the dominant tree” – this is also South Africa’s national tree.
Even more exciting was the realisation that this forest appeared to be in excellent condition and because of limited trail access, was largely unaffected by human intrusion. The team did note that some big trees had recently been felled.
Altogether, these new patches amounted to some 590ha of previously unknown Afromontane forest, which significantly boosts the chances of survival for rare bird species. This brings the national area of Afromontane to about 700ha, more than three times the previous estimate of 200ha.
The Nambas are therefore the most important site for Afromontane forest bird conservation in Angola, the team wrote, and all efforts should be made to recognise their conservation importance, especially since none of the tracts of Angolan Afromontane forest are formally protected.
The Namba Mountains also satisfy the requirements to be named an important bird area because of the presence of a globally threatened species as well as restricted-range species.
More surveys are now needed to accurately capture the population sizes, especially for Swierstra’s francolin, as well as the overall bird diversity.
A survey of human populations and activities in the area and surrounding is also urgently needed, as this would help in drawing up conservation recommendations for the establishment of a new protected area, and to identify the most pressing threats to the biodiversity of the area.