Results of an exploratory survey for future Black Tern studies in coastal wetlands

J. van der Winden
S.K. Nyame
Y. Ntiamoa-Baidu
C. Gordon
 

Summary

Most tern species that breed in Europe, winter along the (West) African coasts. Ghana and The Netherlands are well known for the large numbers of terns, especially Black Terns Chlidonias niger, present after the breeding period in coastal wetlands. The Black Tern is a shared resource for the Netherlands and Ghana: after the birds leave the Netherlands, they move down along the western coast of Africa, with several thousands occurring along the Ghanaian coast in September-October. The numbers of Black Terns spending the non-breeding season in West Africa are internationally important and collaborative efforts between West African and European countries would be crucial to ensure the survival of this species. In the Netherlands Black Terns are endangered as a breeding species due to habitat loss and deterioration of breeding sites. In West Africa Black Terns face probably a future overexploitation of marine fish stocks and increasing human impact on coastal wetlands. The dual international responsibility that Ghana and The Netherlands have for Black Terns, are the main reason for a start of a co-operative Black Tern study between Dutch and Ghanaian ornithologists.

It is therefore not surprising that the Centre for African Wetlands (CAW) selected the Black Tern as the subject for their pilot wetland research initiative. The pilot project seeks to demonstrate the opportunities and feasibility of collaborative field studies between West African and European wetland scientists that promote capacity building and knowledge/lessons sharing. One of the targets was to set up a short field study in autumn 2000 on tern ecology. The overall goal of the preliminary field study was to investigate the possibilities for ecological research on Black Terns and to review the long term waterbird monitoring carried out by the Ghana Wildlife Society (GWS). Part of the goal is to establish a Black Tern monitoring scheme within a regional and international co-operative framework. The ultimate goal would be to obtain complementary ecological information on Black Terns in relation to current threats on the wintering and breeding populations that would inform definition of appropriate management prescriptions. The Pilot Project was also aimed at demonstrating the ability of the Centre for African Wetlands to facilitate research in the sub-region by use of its network of partners. The Centre for African Wetlands invited Bureau Waardenburg to co-operate with the Ghana Wildlife Society (GWS) for this exploratory field study on tern ecology in October 2000.

The short term objectives of the October 2000 study were: organising an expert workshop, evaluating existing monitoring programmes and joint field research work on tern ecology.

Table 2.1 provides an overview of research targets and methods that can be used in future co-operative studies. In table 5.1 these methods are presented for the pilot study area at Densu Delta Ramsar site near Accra for October 2000. The study in October succeeded in achieving most of the goals that were formulated at the beginning of the project. The co-operation between all parties was very successful and the sharing of knowledge substantially contributed to the success of the short study. The Ghana Wildlife Society has great knowledge of all wetlands and their bird population in Ghana. The bird counts are executed in a structured way every month. Apart from this, the Society is involved in intensive studies and conservation programmes on tern trapping by local inhabitants in close collaboration with the Royal Society for the Protection of Birds (UK).

The October 2000 project provided useful information about tern numbers, the relative importance of feeding areas and the relation between local fishermen and terns. A first attempt was made to estimate the food intake of terns following fishermen, which showed a minor impact of terns feeding on the available stocks. This might give credence to or refute the claim by fishermen that terns are a threat to fish stocks. The study also showed that it is possible to catch terns in a short period in significant numbers so monitoring of condition and moult studies are possible.

Black Terns in the Densu Delta area fed mainly near shore around beach seine activities. However, very low percentages of fish were taken from fishermen. Black Terns in Ghana were in normal winter condition and it seemed that food availability was high. The study in October 2000 was very short and the sample size is clearly too small for definitive results and conclusions. However, these results provide some answers and contribute to the understanding of the basic question: what are terns doing in Ghana? In fact the terns profit from the rich marine food resources and it seems that food availability is high enough to support large numbers of terns. The close link with local fishermen emphasises the importance of maintaining fish stocks and preventing overexploitation.

The October study was supposed to be a feasibility study for future tern research. The study showed that this is clearly within the possibilities. Part of the studies that started in October 2000, were continued throughout the season (2000/2001) by the GWS team. An important goal of the pilot study was to explore future co-operative research possibilities. From the results of the Black Tern study in October 2000 the most important recommendations may be summarised as follows (see chapter 5):

• The tern work should be broadened into neighbouring countries.
• The data on monthly collected bird counts should be analysed and written up as
soon as possible.
• In the near future other researchers especially students, should be encouraged to
contribute to tern research studies additional to the GWS staff. Foreign researchers
can strengthen the knowledge on field methods and data analyses.
• Offshore studies have to be included in the future study programme.
• Counts of night roosts, feeding ecology and tern capture have the highest priority.
• It is proposed to strengthen research capacity in Ghana by organising a West African
tern workshop, training of Ghanaian counterparts in The Netherlands, and
expansion of tern studies to other nature and social topics in wetland studies.
 

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