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Publication number 73. Stichting WIWO

Title: Waterbird count of Zanzibar and Pemba Islands
Author(s): Rienk Geene (ed)
Publication date: 2001


Between 8 and 28 January 1998, a waterbird census of Zanzibar and Pemba Islands was carried out within the framework of the 1998 Tanzania Waterbird Count. The fieldwork was done by a team of WIWO, cooperating with the Commission for Natural Resources and the Department of Environment on Zanzibar Island and Pemba. The project resulted not only in good results of the bird count itself, but also proved the productiviness of the established international cooperation. It is hoped that the kind of cooperation that could be established will be repeated in the near future. Suggestions for projects on waterbirds in the future could be: setting up a regular monitoring scheme for the most important areas, carrying out a more complete survey on Pemba and trying to estimate fluctuations in the numbers during the period half December to half April by aerial surveys.

The main result of the waterbird census of Zanzibar and Pemba Islands was the number counted of Dromas ardeola (Crab Plover): a total of 6,017 was found, 4,258 on Zanzibar Island and 1,759 on Pemba. The total number present must have been much higher, because only less than half of Pemba was visited. The total number of Dromas ardeola on Pemba was estimated to be 4,250. Therefore, the total estimate for Zanzibar and Pemba Islands in the winter of 1997/1998 is 8,000-9,000.
The species is the second most numerous wader on the islands. Dromas ardeola was the most evenly spread species over all habitats (sandy beaches, coralflats and mudflats). This gregarious species is relatively easy to count, as it roosts on sandy beaches and not in mangrove trees like many other waders on the islands. Therefore, the estimate for this species is thought to be fairly complete. Dromas ardeola is a wader species with a relatively small population, most recently estimated at 43,000 birds (Rose & Scott 1997). The estimate for Zanzibar and Pemba Islands therefore, means that the islands hold 20% of this species.

The most numerous species on the Islands was Calidris ferruginea (Curlew Sandpiper) with a total of 10,640. The third numerous species was Numenius phaeopus (Whimbrel) of which 5,116 were found. Also the number of 3,276 Xenus cinereus (Terek Sandpiper) is significant.

A remarkable finding was the complete absence of Philomachus pugnax (Ruff), and the near absence of other freshwater wader species. In spite of special efforts made, nearly no waders were found in freshwater areas on inland sites.

On Zanzibar Island three areas held the largest numbers of waterbirds: Chwaka-bay with 11,505 waterbirds, Menai-bay with 6,410 waterbirds and the area in the north-west of Zanzibar Island between Nungwi and Bumbwini (including Tumbatu Island) with 5,981 waterbirds.

In a number of occasions the numbers counted meet the Ramsar criteria listed by Rose & Scott (1997). All three areas mentioned above meet the Ramsar criteria for: Dromas ardeola, Xenus cinereus and Pluvialis sqatarola (Grey Plover). counting site 25 (Northeastern beach) meets the Ramsar criteria for Sterna saundersi (Saunder's Tern): the number of 1,200 found there is three times the 1% level of 400.

On Pemba Island between one third and half of the coast was covered. The south of the Island was much better covered than the north. This is clearly reflected in the numbers presented in this report. It is argued that it is justifiable to estimate that at least twice the numbers counted on Pemba are presen in reality. Kiweni Islan meets the Ramsar criteria for Dromas ardeola and Pluvialis Sqatarola, while also the area just west of Kiweni meets the Ramsar criteria for Dromas ardeola.

The report contains:
  • Introduction and aims
  • Study area and methods
  • Site descriptions
  • Results
  • Annotated list of observed waterdbird species
  • Observations of other bird species