Do neophobia and dietary wariness explain ecological flexibility?: An analysis with two seed-eating birds of contrasting habits

The neophobia threshold hypothesis (NTH) suggests that the acquisition and maintenance of a high behavioral and ecological flexibility in the evolutionary and adaptive history of a species is the consequence of lower levels of neophobia towards new micro-habitats and of dietary wariness of novel foods. To test this idea we assessed the degree of neophobia and dietary wariness in two seed-eating bird species with contrasting degrees of ecological flexibility that inhabit the central Monte desert (Argentina): a grass-seed specialist, the many-colored chaco-finch, and a generalist feeder, the rufous-collared sparrow. We expected that both species would exhibit neophobia and wariness whenfaced with new foraging opportunities but that the rufous-collared sparrow would be less neophobic and less wary than the specialized many-colored chaco-finch. Experimental indicators of neophobia and dietary wariness included willingness to eat near novel objects and willingness to eat novel seeds, respectively. Both species showed similar levels of reluctance to novelty, although the sparrow could be slightly more reluctant than the finch. Contrary to our predictions, the sparrow was neither less hesitant nor faster or greedier than the finch. This experimental evidence does not support a negative relationship between neophobia / wariness and ecological flexibility in these two seed eatingbirds and it coincides with the growing evidence that challenges the NTH. Some of our results provide support for the dangerous niche hypothesis, especially as the rufous-collared sparrow, that feeds on more diverse and potentially dangerous food, showed higher levels of neophobia in some cases. Although the idea of neophobia and wariness being plausible causes of ecological specialization sounds attractive, the current situation calls for further research so that the causes of ecological flexibility in granivorous birds can be better understood.Fil: Camín, Sergio Ramón. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; ArgentinaFil: Martin Albarracin, Valeria Leticia. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Jefferies, María Milagros. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Marone, Luis. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; Argentin