Wintering waterbird assemblages in the central part of the Gulf of Gabès in southern Tunisia

Hamza, F., Hammouda, A. & Selmi, S. (2016). Wintering waterbird assemblages in the central part of the Gulf of Gabès in southern Tunisia. Ostrich 87:  217–223. doi: 10.2989/00306525.2016.1207721
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Abstract

Although the Gulf of Gabès is recognised as an Important Bird Area, several aspects of the ecology of waterbirds inhabiting this area still need to be investigated. We observed how waterbird foraging guilds varied among habitats. In total, 49 species belonging to 16 families were recorded. Winter visitors accounted for 73% of counts. The avifauna was dominated by shorebirds (52% of records), followed by large wading birds (25%), open-water birds (18%) and waterfowl (5%). However, the structure of local waterbird communities and their composition in terms of foraging guilds varied according to habitat type. The bird communities of sandy beaches were dominated by open-water birds, whereas large mudflats were dominated by shorebirds, and wadi estuaries showed a more even representation of foraging guilds. Locally rare species had narrow distributions, whereas locally abundant species were found widely within the gulf. For four species the 1% population level criterion of the Ramsar Convention was exceeded. Overall, our results show that the Gulf of Gabès hosts important numbers of waterbirds with different ecological requirements, which confirms the importance of this gulf as a wintering area for Palearctic waterbirds.

Rassemblements hivernaux chez les oiseaux aquatiques de la zone centrale du Golfe de Gabes en Tunisie méridionale

Bien que le Golfe de Gabes soit reconnu comme une zone importante pour la conservation des oiseaux, de nombreux aspects de l’écologie des oiseaux d’eau qui y vivent restent peu connus. Ainsi, l’objectif de ce travail était de décrire la diversité de l’avifaune hivernante dans ce golfe et d’étudier la variation de sa composition, en termes de guildes alimentaires, entre les différents types d’habitat qu’abrite cette région. Au total, 49 espèces appartenant à 16 familles ont été recensées. Les hivernants représentent 73% des effectifs enregistrés. Cette avifaune est dominée par les limicoles (52% des effectifs enregistrés) suivis par les grands échassiers (25%), les laridés (18%) et les canards (5%). Cependant, la structure des communautés locales et leurs compositions en termes de guildes varient en fonction de d’habitat. C’est ainsi que les avifaunes des plages sableuses sont dominées par les laridés, celles des vasières par les limicoles, alors que les estuaires des oueds abritent une avifaune plus équilibrée. Les espèces localement rares ont une répartition restreinte, tandis que les espèces localement abondantes ont une large distribution dans le golfe. D’autre part, pour quatre des espèces recensées, le critère de 1% de la Convention de Ramsar est atteint. Globalement, nos résultats montrent que le Golfe de Gabes abrite un effectif important d’oiseaux d’eau ayant des affinités écologiques variées, ce qui confirme l’importance de ce golfe pour l’avifaune Paléarctique.

Eurasian Spoonbill, Spatule blanche (Platalea leucorodia) ringed in The Netherlands and observed here in gulf of Gabès, Tunisia.

Eurasian Spoonbill, Spatule blanche (Platalea leucorodia). This bird was ringed in summer 2015 in The Netherlands. During the autumn migration, this spoonbill was observed in the gulf of Gabès, Tunisia. Usually, spoonbills from the Netherlands use the East Atlantic flyway and it is uncommon to observe them in Tunisia. This recovery of Dutch spoonbill is the 4th in Tunisia and the first for the gulf of Gabès (Foued HAMZA)

 

Co-occurrence and commensal feeding between Little Egrets (Egretta garzetta) and Eurasian Spoonbills (Platalea leucorodia)

Hamza, F., & Selmi, S. (2016). Co-occurrence and commensal feeding between Little Egrets Egretta garzetta and Eurasian Spoonbills Platalea leucorodia. Bird Study 63: 509–515. doi: 10.1080/00063657.2016.1238035
PDF in RresearchGate

Abstract:

Capsule: The spatial distribution and feeding efficiency of Little Egrets Egretta garzetta wintering in the gulf of Gabès, Tunisia, are affected by a commensal association with the Eurasian Spoonbills Platalea leucorodia.

Aims: To investigate the role of the interspecific interaction between Little Egrets and Eurasian Spoonbills in shaping the spatial distribution and feeding efficiency of Little Egrets.

Methods: Using count and behavioural data, we examined the co-occurrence of these species in flocks, and compared the foraging efficiency of Little Egrets feeding with Eurasian Spoonbills with that of solitary Little Egrets.

Results: We found that the presence of Eurasian Spoonbills doubled the chance of Little Egrets being present. Within mixed flocks, the number of Little Egrets increased with the number of Spoonbills. Moreover, Little Egrets foraging in association with Eurasian Spoonbills took fewer steps, had higher pecking rates and higher prey intake rates than solitary Little Egrets.

Conclusion: Little Egrets appear to obtain foraging efficiency benefits by following Eurasian Spoonbills. This interaction seems to play a role in determining the spatial distribution of Little Egrets.

 

Eurasian Spoonbills (Platalea leucorodia), Gulf of Gabès, Tunisia (Csaba Pigniczki )

Eurasian Spoonbills (Platalea leucorodia), Gulf of Gabès, Tunisia (Csaba Pigniczki )

Predictors of the abundance of shorebirds and wading birds wintering in the Gulf of Gabès, Tunisia

Hamza, F. & Selmi, S. (2015). Habitat features and human presence as predictors of the abundance of shorebirds and wading birds wintering in the Gulf of Gabès, Tunisia. Marine Ecology Progress Series 540: 251–258.  doi: 10.3354/meps11500

Abstract:

Understanding ecological factors and processes affecting waterbird abundance is a major question in ecology and important for conservation purposes. In the Mediterranean, studies dealing with the determinants of waterbird abundance and distribution have mainly been concerned with European coastal habitats, whereas less attention has been paid to coastal areas in North Africa. In this work, we used count data to investigate the relevance of habitat features and human presence as predictors of the abundance of shorebirds and wading birds wintering in the Gulf of Gabès, a particularly important wintering quarter for many Palearctic waterbirds in Tunisia. We found that the strength and direction of the relationships between bird abundance and both habitat and human parameters varied among species, depending on their ecological requirements. Most species occurred more abundantly in large mudflats compared to narrow sandy beaches, while one species showed an opposite trend. We also found that the studied sites were frequently visited by local people, mainly for clam harvesting, thus sharing the intertidal habitats with birds. However, the abundance of most species did not decrease with increasing human presence, suggesting that traditional clam-harvesting activity did not seem to disturb birds. Nonetheless, we believe that further investigations of the interactions between birds and clam-harvesters are needed to better understand the role of traditional clam-harvesting activity in shaping the abundance and diversity of waterbirds wintering in the Gulf of Gabès.

Related papers (PDFs):

  • Sanderling (Calidris alba) colour-ringed in Iceland, and observed wintering in the Gulf of Gabès, Tunisia (Foued Hamza / Birding in Tunisia).
    Sanderling (Calidris alba) colour-ringed in Iceland, and observed wintering in the Gulf of Gabès, Tunisia (Foued Hamza / Birding in Tunisia).

Species richness patterns of waterbirds wintering in the gulf of Gabès in relation to habitat and anthropogenic features

Hamza, F., Hammouda, A. & Selmi, S. (2015). Species richness patterns of waterbirds wintering in the gulf of Gabès in relation to habitat and anthropogenic features. Estuarine, Coastal and Shelf Science 165: 254-260.
doi: 10.1016/j.ecss.2015.05.025
PDF in ResearchGate.net

Abstract:

Identifying factors affecting waterbird diversity is a major topic in avian ecology, as well as for conservation purposes. In this work, we investigated the relevance of habitat features and human presence in predicting the diversity of waterbirds wintering in the gulf of Gabès, an important but poorly known wintering area of palearctic waterbirds. This includes two major sources of bias in macroecological studies, namely species imperfect detection and spatial non-independence among sampled communities. Our results showed that species richness overall varied among sites according to habitat quality and tidal area use by humans. In particular, large intertidal areas, characterized by high numbers of tidal channels, elevated amounts of mud and organic materials in the sediment and important coverage of seagrass, hosted a greater diversity of waterbirds with different ecological requirements than did the small and relatively homogeneous sandy beaches. Moreover, we found that intertidal area use by humans for clam harvesting was associated with high diversity of waterbirds, particularly shorebirds, suggesting positive effects of clam harvesting on shorebirds. Further investigations of habitat selection processes and foraging behaviors are however needed to more profoundly understand the role of traditional human activities in the intertidal areas of the gulf of Gabès in shaping wintering waterbird communities.

Calidris alba (Sanderling - Bécasseau sanderling): ringed in Iceland in 2011, and wintering in the Gulf of Gabès, Tunisia

Sanderling (Calidris alba). This bird was ringed in Iceland in 2011, and wintering in the gulf of Gabès, Tunisia, January 2013. (Foued Hamza / Birding in Tunisia).

Oiseaux d’eau hivernant dans la zone centrale du golfe de Gabès dans le sud-est tunisien

Hamza, F., Hammouda, A., Chokri, M.A. & Selmi, S. 2014. Oiseaux d’eau hivernant dans la zone centrale du golfe de Gabès dans le sud-est tunisien. In: Feltrup-Azafzaf, C., Dain, M., Brochet, A.L., Defos du Rau, P., Mondain-Monval, J.Y. & Azafzaf, H. (eds.). Bulletin of the network “Mediterranean Waterbirds”, No. 2. AAO, ONCFS, Tour du Valat. pp: 1-10.
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Résumé :

Le golfe de Gabès, dans le sud-est Tunisien, est réputé pour être l’une des zones d’hivernage les plus importantes pour les oiseaux d’eau en Méditerranée. Dans le but d’obtenir une meilleure connaissance de cette avifaune, nous avons effectué, au cours de l’hiver 2012 – 2013, des recensements au niveau de 50 stations réparties entre la baie des îles Kneiss au nord et l’entrée de la lagune de Boughrara au sud. Au total, nous avons dénombré 45 431 oiseaux appartenant à 50 espèces, 16 familles et 10 ordres. Les Charadriiformes et les Ansériformes sont les groupes les plus riches en espèces.  Parmi les 50 espèces recensées, 11 sont sédentaires, 4 sont hivernantes  irrégulières et 35 sont hivernantes régulières. Le Bécasseau variable (Calidris alpina), le Flamant rose (Phoenicopterus roseus), le Gravelot à collier interrompu (Charadrius alexandrinus), le Chevalier gambette (Tringa totanus), le Goéland railleur (Chroicocephalus genei), le Courlis cendré (Numenius arquata), l’Huîtrier pie (Haematopus ostralegus) et le Pluvier argenté (Pluvialis squatarola) sont les espèces les plus abondantes.

Wintering waterbirds in the central area of the Gulf of Gabes in south-eastern Tunisia.

Abstract:

The Gulf of Gabes, in southeastern Tunisia, is reputed to be one of the main wintering areas for water birds in the Mediterranean. To have a better knowledge of this avifauna, we conducted a census in 50 stations from the Bay of Kneiss Islands in the North to the entrance of the lagoon of Boughrara in the South, during the winter of 2012 – 2013. Overall, we counted 45, 431 birds belonging to 50 species, 16 families and 10 orders. The Anseriformes and Charadriiformes groups are rich in different species. Among the 50 species   listed, 11 are sedentary, 4 are irregularly wintering and 35 are regularly   wintering. The Dunlin (Calidris alpina), the Flamingo (Phoenicopterus roseus), the Kentish Plover (Charadrius alexandrinus), the Redshank (Tringa tetanus), the Slender-billed Gull (Chroicocephalus genei), the Eurasian Curlew (Numenius arquata), the Eurasian Oystercatcher (Haematopus ostralegus) and the Black-bellied Plover (Pluvialis squatarola) are the most abundant species.

Related papers:

Hamza F., Hammouda A., Chokri M.A., Béchet A. & Selmi S., 2014. Distribution et abondance du Flamant rose Phoenicopterus roseus hivernant dans la zone centrale du golfe de Gabès (Tunisie). Alauda 82 (2): 135-142.

Platalea leucorodia - Eurasian Spoonbill - Spatule blanche: ringed in 2009 as chick in Hungary, overwintering in the gulf of Gabès, Tunisia.

Platalea leucorodia (Eurasian Spoonbill – Spatule blanche): ringed in 2009 as chick in Hungary, and overwintering in the gulf of Gabès, Tunisia, February 2014. (photo: Foued Hamza / Birding in Tunisia).

Calidris alba (Sanderling - Bécasseau sanderling): ringed in Iceland in 2011, and wintering in the Gulf of Gabès, Tunisia

Calidris alba (Sanderling – Bécasseau sanderling): ringed in Iceland in 2011, and wintering in the Gulf of Gabès, Tunisia, January 2013. (photo: Foued Hamza / Birding in Tunisia).

Distribution et abondance du Flamant rose Phoenicopterus roseus hivernant dans la zone centrale du golfe de Gabès (Tunisie)

Hamza F., Hammouda A., Chokri M.A., Béchet A. & Selmi S., 2014. Distribution et abondance du Flamant rose Phoenicopterus roseus hivernant dans la zone centrale du golfe de Gabès (Tunisie). Alauda 82 (2): 135-142.
PDF in ResearchGate.net

Distribution and abundance of Greater Flamingos wintering in the central part of the gulf of Gabès, Tunisia.

Abstract:

The Gulf of Gabès, in south-eastern Tunisia, is one of the most important Mediterranean wintering areas for the Greater Flamingo Phoenicopterus roseus. However, information on the ecological factors shaping the abundance and distribution of this species in this wintering area are lacking. During the winter of 2010-2011, we conducted repeated counts of flamingos in fifteen sites in the central part of the Gulf of Gabès. The collected data were used to investigate the abundance and distribution of flamingos in this particular wintering area. We found that the total number of flamingos inhabiting the studied area ranged from 262 to 1781, and the proportion of occupied sites varied between 27 and 80%. We also found that the abundance and distribution of flamingos showed a peak between mid-November and mid-January. After this period, the flamingos became gradually rare, as a result of adults’ migration to northern breeding areas. In addition, our results showed that flamingos more frequently and more abundantly occurred in large mudflats (bays and estuaries) than in sandy beaches with small intertidal zones. The formers are likely to present more attractive feeding habitats because of their higher prey availability and accessibility. However, human presence (fishermen and shellfishers) did not appear to affect flamingos’ abundance and distribution. Fishermen and shellfishers did not seem to constitute a threat or a major disturbing factor for flamingos.

Flamant roses - Phoenicopterus roseus - Greater Flamingos

Flamant roses – Phoenicopterus roseus – Greater Flamingos (Photo: Foued Hamza)