Namibia's Endemics

More than 630 bird species have been recorded in Namibia and many of these are superbly adapted to desert conditions. vacationtechnician.com

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World Watch Advisory 03/17/04 04:54 GMT
Authorities warn March 16 2004 that serious floods are likely in northern Namibia in the coming weeks. Namibian Department of Water Affairs officials March 16 warned that impending floods in the Caprivi Strip in northern Namibia are likely going to exceed those seen in 2003 - which was described as a major disaster. Anticipate significant disruptions including road closures in this region in the coming weeks.

Officials have been reporting rising river levels in the Zambezi and Kavango rivers since mid-January. The water level in the Zambezi River March 14 was measured to be at least 1.6 meters higher than last year's level taken at the same time. Authorities estimate that additional rains in southern Angola are likely to push the levels well beyond those experienced in 2003 when floods submerged large parts of the Caprivi Strip and caused serious population displacements. Fears are even expressed that Katima Mulilo - a major town in the Caprivi Strip - may be flooded. Lake Liambezi in southern Caprivi has already begun flooding. Significant flooding may impact the major east-west road running through the Strip connecting Namibia with Zambia and Zimbabwe.

Expect disruptions in road travel and public services, including power outages; allow additional time to reach destinations. Consider postponing road travel to and through affected areas. If travel is unavoidable, carry plenty of food and water, and a radio with spare batteries. A personal satellite locator is also recommended. Avoid driving through water on roadways, as it could cause the vehicle's engine to stall. Do not attempt to move a stalled vehicle; abandon it and immediately move to higher ground.

As always in Namibia, drink bottled water only and use bottled water when brushing your teeth. Flooded conditions may lead to health risks and diseases such as malaria. Monitor media reports for local impact and follow the guidance of local authorities.

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Namibia is a country dominated by deserts. By definition, deserts have low rainfall, low vegetation biomass and, as a result, low species diversity. Or do they?

Judging by Namibia's deserts the reverse is true - at least for endemic species. In reviews of hotspots of endemism in Africa in the early 1990s, the south-west African deserts emerged as particularly rich in reptiles, mammals and birds. This surprising diversity of species, both plant and animal, includes many which have evolved behavioral and physiological adaptations to enable them to thrive in the typically harsh, arid conditions. In addition to those species found in the true desert, distinct species assemblages are supported by Namibia's coast, permanent and ephemeral wetlands and pans, woodland savannas and mountain areas, further enhancing the country's biodiversity. The international importance of Namibia's fauna and flora has recently been formally recognized by the ratification of the Convention on Biodiversity, and the implementation of a National Biodiversity Programme by the Ministry of Environment and Tourism.

More than 630 bird species have been recorded in Namibia and many of these are superbly adapted to desert conditions. Fourteen species are essentially exclusive to Namibia and are classified as national endemics. Of these, four are found only in the strip of Namib Desert adjacent to the coast, while the remaining 10 'inland' endemics thrive in the rugged escarpment parallel to the coast, and the wooded savannas to the east. Although birds are among the best known of Namibia's taxa, largely as a result of the Atlas of Southern African Birds project, conservation initiatives have been hampered by the lack of detailed information on population sizes and distributions, particularly for priority groups such as national endemics and Red Data species.

We came to Namibia in 1993 at the invitation of Dr. Rob Simmons, the Ministry of Environment and Tourism's ornithologist, to jointly attempt a pilot study to estimate the population sizes and delimit the distributions of the 10 core Namibian endemics. In addition to basic population information we wanted to know how well, if at all, the present mosaic of parks and reserves in Namibia protects these species. One of the outcomes of this preliminary study was the first evidence that atlas reporting rates are related to actual bird abundance, that is, that low reporting rates indicate low abundance, and vice versa. The promising success of the methods used, and the vast areas and rugged terrain which these species call home, merited the later expansion of this research into a much more extensive study in 1996, funded by the National Biodiversity Programme.

So, which are these endemic species, and where are they found? They range from the truly desert-loving Rüppell's Korhaan, found on apparently lifeless gravel plains, to the Violet Woodhoopoe, a cavity-nesting species almost entirely restricted to mature riparian vegetation along major river courses and very similar to the Red-billed Woodhoopoe found elsewhere in sub-Saharan Africa. Several of the endemics are very cryptic and easily overlooked, including the enigmatic Hartlaub's Francolin which can occasionally be seen scurrying around koppies, but is more usually detected from the characteristic screeching duet of pairs in the early mornings or late afternoons. Herero Chat is one of Namibia's least-known birds but its lively song, distinctive face-mask and curiosity at intruders make it a welcome sight on the inhospitable hillsides of the escarpment. Similarly, the warbling melody of the Rockrunner often provides the first clue that this elusive bird is skulking among the rocks of a scree slope or koppie.

In contrast to these three species, the conspicuous bouncing flight and whistling call of the White-tailed Shrike make this species the most popular and well known of all the endemics. Equally visible, the distinctive Monteiro's Hornbill with its large bill and grey bib is often seen perched in pairs on tree tops performing a display of vigorous head-bobbing in time to its escalating 'tok tok tok' calls. Carp's Black Tit is usually heard before you can catch sight of it, chattering busily in small groups in well-vegetated areas.

All but a handful of Namibia's rivers are ephemeral - holding water for only a few days each year - yet they support crucial corridors of mature riparian vegetation in often very barren landscapes. These green strips of life are the preferred habitats of the remaining two endemics. Rüppell's Parrot is a very active and noisy bird, flying between favourite trees at high speed in a distinctive flash of vivid blue, yellow and grey-brown. The last of the 10 and perhaps the most raucous, Bare-cheeked Babbler is usually found in family groups foraging in dense foliage, viewing people or animals below with characteristic babbler curiosity.

It is fortunate, or more probably a quirk of evolutionary history, that all these birds are found together. This made our job easier, even though the terrain they frequent is at best hot and rugged; at worst dusty, inhospitable and inaccessible. The four other species considered endemic or near-endemic to Namibia are restricted to the extreme western desert and have significantly different habitat requirements and distributions, and were not included in this study. Three of these are larks: Dune Lark, found largely in the dunes of the Namib Desert; Gray's Lark, typically seen in small groups in the extreme desert; and Namibia's newest endemic, Barlow's Lark, first described in 1996, which has an estimated range of 18 000 square kilometers in the Karoo vegetation in the extreme south-west of the country. Good estimates of population size and range of Namibia's only truly coastal endemic, Damara Tern, have recently been determined by extensive studies coordinated by the Ornithology Programme.

Single-species studies of Namibian endemics have been a high priority, and research investigating aspects such as the feeding and breeding ecology of Rüppell's Parrot, Carp's Black Tit, Monteiro's Hornbill, Violet Woodhoopoe and Bare-cheeked Babbler is either currently underway or has been recently completed.

The 10 inland species were surveyed over seven months using line transect surveys - a method which involves recording the distances of birds from a walked transect line and then using an equation to calculate bird density. By sampling across the range of vegetation types, altitude and rainfall zones within Namibia, estimates were made of bird densities in every area. These densities were then manipulated using sophisticated GIS computer-mapping techniques to produce predictive maps across the country and total population estimates for each of the 10 species.

Overall, most of the species appear to occur in sustainable numbers at a national level, with the most abundant species, the White-tailed Shrike, numbering well over a million birds. Herero Chat, previously thought to be one of Namibia's most rare species, was found to be surprisingly common in its preferred habitats. In prime areas it occurs at localized densities of more than five pairs per square kilometre, making it difficult to miss if you walk for just a few hundred metres whistling or playing tapes of its song (or that of the Rockrunner to which it responds equally well). The Rockrunner itself is also less rare and more widespread than generally assumed: it occurs in many more habitats than scree slopes and koppies - although finding it requires a good idea of what to listen for!

Conversely, the least abundant species, Violet Woodhoopoe, is predicted to number only a few thousand birds, prompting serious concern for its future viability, particularly in view of its recently proven hybridization with Red-billed Wood-hoopoe. A more sinister threat to one of these species, Rüppell's Parrot, is the illegal export of wild birds for the cage-bird trade, suggesting that a careful eye should be kept on the wild population, and greater efforts made to monitor and control unlicensed trapping and trade.

Many of the species showed surprisingly similar distribution patterns with high concentrations of birds in the north-west of the country, extending eastwards to a greater or lesser degree. In order to get an overall picture highlighting the priority areas ('hotspots') for these arid-adapted species, a further analysis was undertaken. An index of diversity was calculated, ranking areas from those with relatively high numbers of all 10 species to those supporting low numbers of only a few species. All the hotspots of endemism identified fall within one vegetation type - the Namibian escarpment - which runs roughly north-west to south-east and is typified by hilly, rocky landscapes incised by ephemeral river courses en route to the Atlantic coast. Prime areas are apparent to the west and south-west of Etosha (between Sesfontein and Khorixas), and within the remote Kaokoveld area in the north-west of the country.

As a direct result of the high densities of endemic birds identified by this study and the fact that it is one of the few places where all 10 species are found, a section of this Kaokoveld hotspot has recently been designated one of Namibia's 21 most Important Bird Areas. This area, covering more than 2 200 square kilometres, encompasses Hobatere Lodge and is located just west of the western edge of Etosha National Park.

Whereas in many countries there is clear spatial separation between hotspots of endemic birds, mammals and reptiles, Namibian endemics are unusual in showing a great deal of overlap. A large majority of the endemic reptiles, insects, mammals, birds and many plants are arid-zone specialists occurring within the same discrete arid zone. In evolutionary terms, this presumably reflects the effects of past processes driving speciation and adaptation to this unique landscape. In practical terms, it means that those sections of the escarpment identified as the centre of endemism for birds are also particularly important for endemic flora and fauna of many other taxa.

Our most important finding, and of crucial concern given the steadily increasing human pressure on the environment, is the fact that virtually none of these optimal areas falls within any protected area or national park. We hope that, ultimately, the proclamation of further conservation areas linking Etosha National Park with the Skeleton Coast Park will result from this and related research on endemism in Namibia. Because we can now pinpoint the 'best' areas (those areas with the highest species richness and viable populations) for the conservation of endemic birds and because Namibia's other endemic taxa overlap extensively with birds, we can begin to identify precise localities where core protected areas could be positioned to maximize the species' conservation.

NamibiaReading

Namibia’s Himba People
The Kaokoveld Wilderness
Namibia's Endemics
Etosha National Park
Big Sky... Big Earth
Skeleton Coast
Birding: Impalila Island and the Eastern Caprivi

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