Nest-site selection of Western Reef Heron ('Egretta gularis') in relation to mangrove ('Avicennia marina') structure in the Persian Gulf: Implication for management

Abstract

Mangroves are predominantly intertidal habitats that occur worldwide in the (sub) tropics along sheltered and shallow water coastlines. Evidence suggests that mangroves are of critical importance for some mangrove-dependent waterbirds as nesting areas, however, a lack of research is a major impediment to an evaluation of their mangrove dependency and the role of mangrove structure for nesting. We modeled the nest-site selection of Western Reef Heron ('Egretta gularis') as a function of grey mangrove ('Avicennia marina') structure in Hara Biosphere Reserve, Persian Gulf. To infer nest-site preferences, we used logistic regression and AIC model selection to compare nest habitats. We also modeled the mangrove structure as predictive factors for the number of nests in each tree. The nest-site selection of Western Reef Heron was a function of mangrove height and the diameter of the canopy. The crown depth and diameter of mangrove trunks received less support as predictive factors for being selected as nesting trees. Similarly, the most important factor determining the abundance of Western Reef Heron nests in mangroves was the diameter of the mangroves' canopy, followed by the height of mangroves. The diameter of mangroves trunks and crown depth received less support as effective factors for the availability of suitable nesting areas. The resource selection probability function from these models can be applied to assess the suitably of forest stands as Western Reef Heron nesting habitat in Hara Biosphere Reserve, Persian Gulf.