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).