The exotically named Baia dos Tigres (Bay of Tigers) is one of the most remote and inaccessible places in southern Africa. Positioned at the northern end of the Namib Desert, on the Angolan coast, this is a land of sand dunes, wind, rocky plains and ghostly islands.
Getting a chance to travel there and continue my tern research was a dream come true. As a member of a larger biodiversity initiative between South Africa and Angola, I had set myself the challenge of solving a mystery and, in doing so, I fulfilled a lifelong ambition to visit the Angolan desert.
The Bay of Tigers lies about 50 kilometres north of the mouth of the Cunene River (which forms the Angola/Namibia border), along the unknown desert shores of Angola. Twenty-seven years of civil war have made access into the country difficult, with atrocious roads and several landmine-riddled, no-go areas in the southeastern and northern regions; fortunately, the south-western corner and Angola’s largest national park, Iona, are free of mines.
It was with a heightened sense of adventure that, in January 2009, I found myself alone and driving my trusty 23-year-old Toyota Hilux carefully from the team’s base in Lubango toTombua and thence down the coast. As in any coastal desert, it was an awesome experience being flanked by dunes and treacherous seas, or sometimes by occasional bays and sand flats. A mishap here would require nothing less than a two-day slog through sand and wind to the nearest help, and even then there would be no certainty of success. Doing it alone added a distinct edge to the excitement; all my biodiversity colleagues had decided that the inland riches were more attractive than the cold, unforgiving coast and they had departed to Bicuari National Park and other hot, sticky locations inland. How misguided they were!
… we can tentatively estimate the breeding population of Damara Terns in Angola to be just under 200 pairs
My mission was to try to discover if the globally Near-Threatened Damara Tern Sterna balaenarum occurred in the region in any numbers and, more specifically, to find any evidence of it breeding. This diminutive, coastal-breeding seabird has its stronghold in Namibia, where it has been well studied by the Braby family for almost 20 years. Their research has revealed that although global populations are higher than previously thought (a single flock of 7 000 birds caused earlier estimates to be raised), off-road disturbances severely compromise the species’ nesting success. Mining for diamonds in Namibia’s south-western Diamond Area also jeopardises the Damara Tern’s survival by adding sediment to the sea, thus reducing access to fish prey just offshore.
A declining population of about 125 pairs of Damara Terns is known from South Africa, but the only figures from Angola derive from a survey done a decade ago by Dr Alison Sakko. She found 280 Damara Terns along the coast, primarily in the vicinity of the Bay of Tigers, but saw no evidence of them breeding.
I did a three-day survey in search of the birds by driving the length of the 200-kilometre coast, from Tombua in the north to the mouth of the Cunene, but I concentrated my efforts on the series of bays that lie opposite Ilha dos Tigres (the Island of Tigers).
Looking across the 15 kilometres of water to the fishing village of Ponta da Armacao, I was surprised to distinguish a town hall, a huge water tower and even a church, all relics of a settlement built by the Portuguese in the 1950s. Looking across at night, I was equally taken aback to see no lights at all, and I concluded that this eerie place had been deserted by humans and appropriated by birds and seals. A legacy of the time when it was inhabited by people is obvious from satellite images of the area: a long, snaking water-pipe that once supplied the island with fresh water from the Cunene River. In about 1973 the sea broke through the spit of land linking the island to the mainland and took the pipe with it. Remnants of the structure act as a stark reminder of the heavy hand of man, even in this wild and remote landscape.
Climbing to the top of the dunes to view the island and the bay, I discerned three large black masses along the island’s shoreline and deduced that these were large flocks of Cape Cormorants, a species that I had frequently seen fishing just offshore or flying in long skeins over the water.
On one occasion I looked out to sea and noticed a huge, dark shape moving slowly over the surface, about two kilometres offshore. A closer view revealed it to be a massive flock of cormorants, numbering many thousands of individuals and presumably tracking a school of fish.
Flocks of shorebirds were relatively scarce at the start of my journey from Tombua, even though I had been told that Damara Terns might occur at this old fishing town. I was lucky enough to get an escort to guide me along the sometimes heart-poundingly long wall where the dunes meet the sea; the only way to cross without mishap is at low tide. Once in the Baia dos Tigres area, the narrow beach widened and the first flocks of birds I saw were African Black Oystercatchers. An unexpected and rare species in this country and seldom recorded before 1999, these oystercatchers now appear to be as common along this stretch of Angola as they are on central Namibian beaches.
Even more surprising was the presence of a species new to the Angolan list: a migrant Eurasian Oystercatcher calling amongst its African counterparts. I saw another one the next day, which may well have represented a second bird. Eurasian Oystercatchers are seen occasionally in Namibia, but seldom more than two at a time. Further surprises were in store while I was looking for Damara Terns in the large, amorphous flocks of roosting terns. The aggregations comprised mainly Sandwich Terns, with a few Royals, a species that is seldom seen in southern Africa but frequent in Angola, and Caspians. Careful scrutiny of these flocks revealed the unmistakable Swift Tern with its yellow bill; I counted 16 birds (including one freshly dead individual). Although this species is common to the south, in Namibia and South Africa, I later discovered that it had been recorded only once previously in Angola and it was thus a very rare species this far north.
Among the five species of terns I saw, the Damara Terns were noticeably the smallest and they tended to gather on their own. The first major flocks occurred on the sand-and-shell spits that are found at several places down the coast. I searched them carefully for young birds and watched for adults carrying prey, which would indicate that they might be feeding young.
A few young birds were present but there was no movement inland, so all indications were that this was a post-breeding flock. I moved down the coast and located a second, smaller flock where the water-pipe once headed out to the island, but there was still little evidence of breeding.
I continued my journey south along the coast amid the increasing quantities of driftwood carried down the mighty Cunene River and deposited on the shore for tens of kilometres. Late one afternoon, about 35 kilometres north of the Cunene River mouth, I heard the clearly identifiable ‘tchisseek’ of calling Damara Terns. On closer inspection I could see immediately that the birds were carrying fish, executing their exaggerated display flights – and heading inland. Excited, I camped there that night, and at first light followed the already active birds inland. By walking quietly across the gravel plains, I hoped to put up any incubating birds, which would come to mob an intruder.
I was soon in luck as a small white blob with a black head came powering towards me, intent on seeing off this unusual-looking interloper. I backed off and sat patiently, waiting for the bird to return to its nest and watching for its characteristic waddling gait across the gravel, which is a dead giveaway as it covers the last few metres to the nest. I did not have long to wait and had soon located the first known Damara Tern nest in Angola. Within about four hours, I had found another five nests, four with new eggs and one with a chick. Elated, I could now justify the long time spent away from home and the deviation to the desert coast.
The flock that first alerted me to the possible presence of nests had by this stage increased to about 280 birds, all of which appeared to be courting, calling and cavorting as if this were their last chance at genetic immortality. If all those pairs attempted to breed and we add that number to the youngsters I had previously counted, we can tentatively estimate the breeding population of Damara Terns in Angola to be just under 200 pairs and the total population to be approximately 570 individuals.
The long trip home revealed living and dying green turtles (one seemingly beheaded by a shark) near the Cunene mouth, assorted larks and the countless Welwitschia plants that dominate the open grassy plains in arid Angola. It had been a memorable first trip to that country, one made even more so by the successful pursuit of those small white terns in the endless desert.
Acknowledgements
Professor Brian Huntley and Gigi Laidler organised visas and provided funds to make this trip possible. While in Angola I was assisted by, among others, General Traguedo, Mike Mills, Rico Sakko and Frances Crawford. I am eternally grateful to all concerned.
This article was taken out of the December 2009 / January 2010 edition of Africa Birds & Birding. Text and photographs by Rob Simmons.
