•NIwo•

•XATERvOG•-•

WADERS OF THE GULF OF GABPS, , JANUARY TO MARCH 1984 bY Arerid J. van Dijk, Klaas van Dijk, Lieuwe J. Dijksen, Tom M. van Spanje and Eddy Wymenga

From 19 January to 19 March 1984 a Dutch expedition visited the Gul• o• Gab•s along the south coast o• Tunisia (Figure 1) to study the wintering populations o• Palearctic waders and water•owl in this intertidal area. This paper summarises the •indings o• the expedition.

In general the Mediterranean is considered to be almost tideless, but in the Gul• o• Gab•s a significant tidal range o• up to two metres exists, and there are extensive tidal mud•lats. According to Prater (197&)• the number wintering. waders in the Mediterranean is low, but Smart (1985) and Czajkowski (in Cramp and Simmons 1985) have mentioned the region o• the Gul• o• Gab•s as an important wintering area •or thousands o• waders. These •igures suggest much larger total numbers than given by Prater (197&) but up till now precise data have been lacking. On the initiative o• the International Water•owl Research Bureau (IWRB), a Dutch expedition - 'WIWO Tunisia Pro3ect 1984' - carried out investigations in the Gul• o• Gabks. The principal aims o• the expedition were: 1. a complete census o• the wintering population o• waders and water•owl in the intertidal areas in the Gul• o• Gab•s. 2. to catch and ring waders to collect information on biometrics and geographical mudflats origins. 5. to quanti•y the standing crop o• the macrobenthic invertebrates o• the Figure 1. The Gulf of Gab%s in Tunisia. Fine dotted intertidal mud•lats. areas are extensive mudflats. Special attention was paid also to the Greater Flamingo Phoenicopterus ruber.

The 'WIWO Tunisia Pro3ect 1984' was one o• the Our thanks •or their co-operation go to the •irst pro3ects o• the WIWO• the Dutch Tunisian authorities, ornithologists and local Foundation •or International Wader and people. The help and advice o• several Water•owl Research. This •oundation was ornithologists and authorities in the established as a result o• earlier Dutch wader Netherlands, Britain and France was also very expeditions to Mauritania and Morocco appreciated. (Altenburg et aZ. 1•82• Van Brederode et al. 1982, Kersten e• aZ. 1985). The 'WIWO Tunisia CENSUSES Pro3ect 1984' was •inanced by The World Wildlife Fund - The Netherlands• Netherlands In the period • - 22 February 1984 we carried Ministry o• Agriculture and Fisheries, The out one complete census o+ most o{ the Netherlands Foundation •or International Nature intertidal areas in the Sui+ o• Gab•s (Fiqure 1 Protection (Van Tienhoven Stichting), and Table 1). We counted a total o+ 242 000 Bei3erinck - Popping Fund o• the Royal •aders and most o+ them were concentrated in Netherlands Academy o• Sciences, Foundation the Kneiss area (161 000). Parts o+ the Kneiss Tour du Valat and the International Water•owl area we counted twice (in January and Research Bureau. o 18

February>: the numbers were similar. On several inland lakes as well as the Gulf of Gab•s Table 2. Countsof the GreaterFlamingo Phoenicopterus ruber Greater Flamin0os were counted (Table 2). The at several locations in Tunisia in 1984 February counts gave a total of 24 729 Flamingos. We could identify 41 individual Location Date Number Flamingos which had been ringed with plastic coloured leg rings in the Camargue (France), Lake 21 Jan 10530 and 1 bird with a neck-collar, originating either from Iran (Lake Rezaiyeh) or the USSR. A Lake Ichkeul 22 Jan 0 Stax - La 26-28 Jan 9739 local fisherman brought us a Flamingo tarsus with a Russian ring. Sidi Mansour 29 Jan 0 Gulf of Gabes 9-22 Feb 10086 Near we identified a colour-marked Sebkhet 16 Feb 44 coast near Monastir 16 Feb 3 Cormorant Phalacrocorax carbo ringed in 1983 in the Oostvaardersolassen in the Netherlands. Halle el Menzel 16 Feb 316 Lake Tunis 19 Feb 5700 CATCHING Sebkha Sedjoumi 19 Feb 8500 Sebkhet 22 Feb 80 We mist-netted 657 waders during two dark moon Lake Ichkeul 18 Mar 0 periods: between 50 January - 8 February 1984 •e trapped 188 waders in the intertidal area

Table 3. Numbersof waderscaptured during January - March 1984 in near Thynaand in the Kneiss area, Tunisia. Retrappedis ringed and recaptured at the sameplace.

salines at Thyna Kneiss area Total

newly retrapped total newly retrapped total ringed ringed

Oystercatcher Haematopusostralegus - - - 2 - 2 2 Avocet Recurvirostra avosetta 1 - 1 2 - 2 3 Stone Curlew Burhinus oedicnemus - - - 1 - 1 1 Ringed Plover Charadrius hiaticu•a 1 - 1 1 - 1 2 Kentish Plover Charadrius alexandrinus 9 1 10 42 3 45 55 Grey Plover Pluvialis squatarola 2 - 2 38 - 38 4Q Little Stint Calidris minuta 22 - 22 10 0 10 32 Curlew Sandpiper Calidris ferruginea 18 1 19 3 0 3 22 Dunlin Calidris alpina 118 5 123 292 5 297 420 Black-tailed Godwit Limosa Zimosa 1 - 1 Curlew Numenius arquata 2 - 2 5 - 5 7 Redshank Tringa totanus 7 - 7 63 i 64 71 Greenshank Tringa nebularia - - - 1 - 1 1

near the salines of Thvna (7 km south of Sfax), REFERENCES and between 25 February - 14 March 1984 we trapped 469 waders in the Kneiss area (Table Altenburg,W., Engelmoer,M., Mes,R. and 5). Notably, we did not catch any previously Piersma,T. 1982. Wintering waders on the rlqged wader. Resightings of marked birds, and Banc d'Arguin, Mauritania. Stichting Veth recaptures, seem to indicate that the wintering tot steun Waddenonderzock, Leiden. population of waders in the salines of lhyna Brederode,N. van, Kersten,M., Piersma,T. and was rather stable. Zegers,P. 1982. Netherlands wader expedition to Morocco 1982 - some AVAILABLE MACROBENTHIC STOCK preliminary results. Wader Study Group Bull. 56: 12-14. In general, the intertidal mudflats were muddy Cramp,S. and Simmons,K.E.L. (ads.) 1985. •he and covered with vegetation (e.g. Eel-grass Birds of the Western Palearctic, Volume 3. Z•)stera spp.). In the Kneiss area, 9 localities Oxford University Press. of these mudflats were sampled for macrobenthic Kersten,M., Piersma,T., Smit,C. and Zegers,P. biomass. First results show that Cerithium 1985. Wader migration along the Atlantic vulgatum was the most common mollusc, living on coast of Morocco, March 1981. RIN report the surface in densities up to 5000 per m=. 85/20, Texel. This species is not thought, however, to be an Prater,A.J. 1976. The distribution of coastal important prey species for waders since it has waders in Europe and North . In a very heavy shell. M.Smart (ed.), Proc. Int. Conf. on the Conservation of Wetlands and Waterfowl Total biomasses averaged about 20-25 g ash-free (Heiligenhafen 1974), Slimbridge. pp. dry weight per m=, half of it being Cerithium 255-271. vulgatum. Important prey species for waders were the bivalves Abra spp. and Cardium spp., Smart,M. 1985. Importance of the 8ulf of 8ab•s Nereis-like polychaetes and tube dwelling in southern Tunisia for passage and polychaetes. wintering waders. Wader Study Group Bull. 57:7. Full results of the expedition will published in an expedition reoort. WIWO - Tunisia Project 1984, Mounehoek 42, 9265 TL Gatlip, The Netherlands.