Seabirds off Senegal, West Africa: 1

by Tony Marr, Dick Newell and Richard Porter, from Bulletin of the African Bird Club, volume 5.1, March 1998.

Despite its location on the extreme western coast of Africa, Senegal has attracted attention from only a few intrepid seabird observers. This is surprising given the unique location of the capital, Dakar, on a low-lying peninsula, the tip of which projects 50 km out to sea from the main north-south line of the coast, offering exceptional opportunities for observations, especially in autumn. The results of our seawatching efforts, presented here, are relatively modest, yet significant. The potential is enormous, and one of the purposes of this paper is to stimulate more interest and observation. Dakar may prove to be one of the best seawatching locations on the eastern Atlantic seaboard. Prolonged observations from Cap Vert, at the western tip of the peninsula, could provide much valuable new information on the status and distribution of many seabirds where much remains to be learnt about their migration patterns.

Early observations
With the assistance of Dr W.R.P. Bourne, we have been able to trace a few accounts of observations prior to our first visit in April 1992. The earliest is an account of 25 hours seawatching in April 1968 by Gaston (5), who recorded small numbers of unidentified shearwaters Calonectris spp. or Puffinus spp., skuas Stercorarius spp. (mostly Arctic S. parasiticus) and terns Sterna spp. (including some Roseate S. dougallii, 53 Royal S. maxima and 2,042 Black Tern Chlidonias niger).

In February and March 1976, Brown (4) made observations on seabird distribution off Senegal in the course of a hydrographic survey between there and the Cape Verde Islands, the nearest of which lies 460 km west of Senegal. The dominant species he observed offshore over the continental shelf included Pomarine Skua, Stercorarius pomarinus, Great Skua, Catharacta skua, and Royal Tern, with Grey Phalarope, Phalaropus fulicarius, Leach's Storm-petrel, Oceanodroma leucorhoa, and Madeiran Storm-petrel, O. castro. Brown provides a useful list of 16 references from other observers who, as he puts it, 'have passed through the area, usually briefly' and which appear mostly to be of observations from boats. He also states that there have been brief notices in the journal Sea Swallow.

Cape Verde Shearwater, Senegal (B.A.E. Marr)

In 1990, French observers seawatched from Cap Vert for 40 hours between 28 August-9 December and in 1991 for 145 hours between 30 July-5 September (2). These appear to have been the first concerted autumn seawatches, and the results were a revelation.

The 1990 records included the first Bulwer's Petrel, Bulweria bulwerii, for Senegal (seven on one day) and the first records from land of Little Shearwater, Puffinus assimilis, (three on one day); the first and second records of Mediterranean Shearwater, Puffinus (puffinus) mauretanicus; 1,582 Sooty Shearwater, Puffinus griseus, which had previously been known as 'rather rare' off Senegal; 452 Grey Phalarope, 'the first time that such a passage has been noted in Senegal'; 104 Long-tailed Skua, Stercorarius longicaudus, which had been recorded only three or four times previously; 734 Sabine's Gull, Larus sabini, where 'previously only seen in very small numbers', in May; 100s of other Stercorarius skuas; 1,000s of terns of various Sterna species and 1,300 Black Tern; regular small flocks of Cory's Shearwater, Calonectris diomedea; and one Great Skua.

The 1991 French team recorded totals of ten Mediterranean Shearwater, 756 Grey Phalarope, 24 Long-tailed Skua, four Great Skua, 3,500 Royal Tern, 17 Lesser Crested Tern, Sterna bengalensis, 15,300 Arctic Tern, Sterna paradisaea, and 15,800 Black Tern.

Between 9-23 October 1994, G. Allport seawatched on five occasions on three days off Point des Almadies (1) d. In light north-westerly winds, he counted 1,000s of Sooty Shearwater, Pomarine Skua and terns passing; 100s of Cory's Shearwater and Arctic Skua; and smaller numbers of Grey Phalarope, Long-tailed Skua and Sabine's Gull. He also recorded one Bulwer's Petrel, four Manx Shearwater Puffinus puffinus and one Little Shearwater, five Gannet Sula bassana, three Great Skua and one Sooty Tern Sterna fuscata.

The authors' observations
We have made one spring and four autumn visits to Senegal between April 1992 and November 1997, combining seawatching from Cap Vert with pelagic trips in a game-fishing boat chartered from the Centre de Peche Sportive in Dakar. These visits stemmed from a one-day flying visit from The Gambia which DN, Frank Hamilton and Robin Jolliffe made on 23 November 1988 with Air Afrique, who run this game-fishing operation out of Dakar. The birds seen during a pelagic trip of just a few hours included 64 Cory's Shearwater, 21 Great Shearwater, Puffinus gravis, 15 Pomarine Skua, one Long-tailed Skua and two Sabine's Gull, and were sufficient to convince them of the potential. In subsequent visits, we have also seawatched from Pointes des Almadies in spring, and from Isle Ngor in autumn.

Our pelagic trips have principally concentrated on an area south of Pointes des Almadies in spring and another north-west of Isle Ngor in autumn. During autumn visits, we encountered fishing trawlers on most trips with impressive concentrations of birds around them. All our pelagic observations were conducted within 25 km of land.

[The full article appearing in the Bulletin contains a series of tables of observations. Table 1 shows the coverage and observers during our five visits; Table 2 the totals for the spring visit in April 1992; Table 3 the totals from land during the autumn visits; and Table 4 the totals at sea during the autumn visits.]

Wilson's Petrels, Senegal (B.A.E. Marr)

Spring results
The April observations were notable for a northward passage of Wilson's Storm-petrel, Oceanites oceanicus, European Storm-petrel, Hydrobates pelagicus, one Madeiran Storm-petrel, 100s of Stercorarius skuas and Sabine's Gull, and 1,000s of terns, including 96 Roseate and over 10,000 Black Tern. A full account can be found in Marr & Porter (7).

Autumn results
Autumn visits were made in October 1995, October 1996 and two in October and November 1997, and revealed a heavy southward passage of seabirds close inshore at Isle Ngor, principally comprising Sooty Shearwater, Pomarine Skua, Sabine's Gull and Black Tern, with well over 1,000 in a day on some occasions for each of these species. Additional species recorded included Wilson's and Leach's Storm-petrels, Bulwer's Petrel, Little and Great Shearwaters, Brown Booby, Sula leucogaster, Audouin's Gull, Larus audouinii, and many 1,000s of Sterna terns of nine species. Perhaps the most interesting observations were of Cape Verde Shearwater and Catharacta skuas considered to be South Polar Skua, the presence of which had previously gone undetected. Both were recorded in significant numbers.