Spatiotemporal variation of a Pinus seed rain available for an endemic finch in an insular environment |
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Authors: | Eduardo Garcia-del-Rey Nikos Nanos Unai López-de-Heredia Pascual Gil Muñoz Rüdiger Otto José María Fernández-Palacios Luis Gil |
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Affiliation: | 1.Departamento de Ecología, Facultad de Biología,Universidad de La Laguna,La Laguna, Tenerife,Spain;2.School of Forest Engineering,Technical University of Madrid,Madrid,Spain;3.Sección de Montes, Medio Ambiente, Cabildo Insular de Tenerife,Santa Cruz de Tenerife,Spain |
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Abstract: | A major goal of avian ecological research is to determine how distribution and abundance of preferred resources available influence population dynamics and contribute to understand life-history characteristics. Food is widely considered the ultimate factor influencing these traits. We studied, with seed traps, the spatiotemporal variability of Pinus canariensis seed rain during 2007–2008, as a means to explain why a post-dispersal seed predator of conservation concern, the endemic blue chaffinch Fringilla teydea, can adjust its annual life cycle with this variation in an insular environment. Generalized linear mixed models and geostatistical tools were used. Results highlight that temperature and relative humidity are important predictors of seed release rates. Additionally, a high temporal variation was detected in seed abundance (i.e., peaks of massive seed release during the summer months, intermediate values in the autumn, and minimum release rates in winter and spring). Finally, within-stand spatial variation in seed flux was surprisingly large with the most productive microsites receiving three to four times more seeds than the least productive ones. Pine seeds showed a high protein value and a low germination rate. Based on these findings, we suggest that the fortunes of the blue chaffinch should be intimately related to spatiotemporal annual P. canariensis seed crops, temperature acting as a proximate cue, and food availability as the ultimate factor. For the endangered blue chaffinch population on Gran Canaria, we recommend, until more data are available, improving the seed supply during the winter season, either artificially (feeders) or naturally (planting Myrica faya shrubs). |
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