In temperate and tropical regions agricultural conversion of natural habitat typically has negative impacts upon the diversity and functional complexity of bird communities. In arid environments however, the irrigation associated with agricultural can lead to an increase in local abundances of plant and insect resources, so has the potential to benefit bird communities. South Sinai is a key migratory corridor for many birds making the annual journey from wintering sites in Africa to breeding sites in Europe. We assess the importance of traditional Bedouin agricultural gardens for both resident and migratory species by comparing the density and functional composition of birds within the irrigated gardens to those in the unmanaged desert habitat. Estimated bird densities were significantly higher within the gardens than the unmanaged habitat, with a higher estimated species richness within the gardens. Functional composition of bird communities differed between the two habitats, with gardens supporting a higher proportion of insectivorous and migratory birds in addition to the resident desert species that were associated with the unmanaged habitat.Migratory species were almost entirely absent from the unmanaged habitat, suggesting that this region may not be used as a migratory stop-off if not for the presence of traditional agricultural gardens.Keywords: birds; desert; functional richness; migration; oases
IntroductionThe impact of anthropogenic land-use on bird communities has received limited attention in arid regions. In temperate and tropical regions, land-use change such as agricultural conversion of natural habitat typically lead to the disruption of bird assemblages and a loss of functional diversity (Tscharntke et al., 2008;Flynn et al., 2009), but initial research suggests that the irrigation associated with agricultural systems and gardens in arid regions can actively increase the functional diversity of plants (Norfolk et al., 2013) and increase the abundance of pollinators (Gotlieb et al., 2011) and birds (Selmi & Boulinier, 2003;Khoury & Al-Shamlih, 2006). Human population growth and land-use change in arid environments are likely to have direct impact upon local bird communities, but may also have implications for the estimated 4 billion birds that make the bi-annual migration across the Saharan-Arabia desert belt, passing between wintering sites in Africa and summering sites in Europe (Frumkin et al., 1995). In order conserve the migratory routes of these species it is important to understand how birds and humans are interacting in the en route arid environments.Crossing the inhospitable expanse of the Sahara desert can pose a major ecological challenge for birds, one which imposes an exceptional energy demand (Zduniak et al., 2013).Strategies for desert crossing differ between bird groups, with raptors tending to use soaring flight and small passerines flapping flight which allows them to fly through the night and avoid high temperatures (Bruderer, 1994;Chernetsov, 2006). Many passerines m...