Research Highlights (2014, 2013)

Luis M. CARRASCAL, MNCN-CSIC

 

 

Topic: small man-made pinewood islands only capture widespread and habitat generalist avian species with increasing population trends, not contributing to enhance truly woodland species.
           * We evaluate the effect of three categories of factors as predictors of the interspecific variation in bird habitat occupancy of fragmented afforestations funded by the Common Agrarian Policy within a landscape dominated by Mediterranean agricultural habitats.
           * Many species with marked habitat preferences for woodland habitats were very scarce or were never recorded in this novel habitat. Interspecific variability in occurrence was mainly explained by regional distribution patterns: occurrence was significantly and positively associated with the proportion of occupied 10x10 UTM km squares around the study area, regional habitat breadth, and population trend of species in the period 1998-2011. Read more.

 

 

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Topic: thermoregulation benefits of foraging patch selection are discernible in small endotherms.
           * In winter, foraging activity is intended to optimize food search while minimizing both thermoregulation costs and predation risk.
           * Our results support the influence of both thermoregulation benefits and predation costs on feeding patch choice. The influence of distance to refuge (negative relationship) was nearly three times higher than that of temperature (positive relationship) in determining total foraging time spent at a patch. Light intensity had a negligible and no significant effect.
           * This pattern was generalizable among species and individuals within species, and highlights the preponderance of latent predation risk over thermoregulation benefits on foraging decisions of birds wintering in temperate Mediterranean forests Read more [… y más]

 

 

Topic: species richness can decrease with altitude, but not with habitat diversity.
            * We provide an alternative explanation for the suggestion made by Allouche et al. (2012) that species richness decreases at high levels of habitat diversity because the area available per habitat decreases.
            * Reanalyzing their data for Catalonian birds, the unimodal relationship between altitudinal range and richness merely reflects the well-known hump-shaped relationship between species richness and altitude. Bird-species richness shows a hump-shaped relationship with mean elevation, a negative linear relationship with altitudinal range, and a positive, monotonic relationship with habitat diversity, as predicted from classical ecological theory. Read more.