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Nest-site selection and breeding success of the Grey Hypocolius ( Hypocolius ampelinus) were surveyed in relation to plant structure in 2010 and 2011 in southwestern Iran. Microhabitat parameters such as Ziziphus nummularia as the main shrubs used for nesting, were measured in 20 × 20 m plots around the nest and compared with random plots. There were no best clear model for predicting the nest-site selection, however, plant variables especially the canopy cover and diameter of the Z. nummularia, were the most important determinant for nest-site selection ( wi = 0.5). Grey Hypocolius preferred areas with a higher density of Z. nummularia than other available habitats (28.21 vs 1.2 of cover). There was no strong predictor for breeding success, the best models incorporated either Z. nummularia density or diameter (with model weights of 0.25 and 0.17, respectively). Nests of Grey Hypocolius had a higher chance of success at higher densities of Z. nummularia in nesting plots. We found that a higher density of Z. nummularia improved both the probability of nest-site selection and the breeding success of Grey Hypocolius. Shrubs with greater diameters were more likely to be selected for nesting, but had lower breeding success. To identify the key reasons of nests being successful, more habitat parameters should be monitored. The majority of failure in breeding occurred during the incubation stage (52%).

Understanding the factors that influence avian reproductive output is critical for bird conservation as they reveal key considerations that directly impact a species’ long term survival and should be integrated into management plans. To better this understanding for the little bittern Ixobrychus minutus, we investigated how their breeding success relates to breeding time, nest size, water depth, and egg size in a man-made wetland (Ab-bandan) during the 2008 breeding season in Mazandaran Province, northern Iran. For each nest, the dates of the first egg laying, the first hatching, and the first fledging were recorded as well as clutch sizes. Nest size parameters (height, depth, and diameter), water depth under the nest, and egg characteristics (shape index and weight) were measured. The first egg was laid on March 21 and the last chick left the nest on June 24. From 140 eggs in 25 nests, 127 eggs hatched (91%) and 121 fledglings left their nests (87%). Generalized linear modeling revealed that nest diameter positively affected breeding success ( p = 0.001) meaning larger nests were more likely to produce fledglings. Further studies will be necessary to elucidate the underlying mechanisms.

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