Habitat characteristics and seed crops used by Blue Chaffinches Fringilla teydea in winter: implications for conservation management

Abstract

Tree cover and seeds on the ground influence the occurrence of Blue Chaffinches during the non-breeding period. To study the feeding habitat selection of the common Tenerife Blue Chaffinch race during the nonbreeding period as a desperate measure to conserve the endangered Gran Canaria race, whose critical area was burnt in the summer of 2007. Basic statistics were used to test for differences between occupied sites (n = 35) and available representative sites (n = 35). Univariate classification tree models were applied to explore the relationship between a single response variable (presence–absence) and multiple explanatory variables and the relative importance of these. Pine seed availability was quantified on the trees (n = 70) and on the ground (n = 140; 1 × 1 m plots). We found a non-random feeding habitat selection by Blue Chaffinches on Tenerife. During the non-breeding period Blue Chaffinches selected those areas for feeding on pine seeds where the tree cover was higher than 38% (mature areas with tall and thick trees with good crops). When the tree cover was lower than 38%, the mean number of seeds on the ground influenced the presence of this finch (> 0.05 seeds per m2). This study highlights that Blue Chaffinches primarily select sheltered sites for feeding during the non-breeding period. The selection of less sheltered sites seems to be mediated by pine seed availability. Therefore, in this endemic forest system, perceived predation risk, food abundance and availability, and overall availability of safe foraging options are all possibly determining the winter feeding habitat selection. We recommend selective cuts in high-density pine stands to recreate those conditions that allow the pine trees to set seed and management aimed at creating a structure of dispersed small-area compartments with mature trees that provide food and shelter. The installation of artificial feeders seems to be a post-fire priority action for the conservation of the Gran Canaria race.