Food delivery rates increased with forest canopy cover and nestling growth improved with arachnids in the Masked Gnatcatcher Polioptila dumicola.

摘要: Food resources are linked to habitat characteristics and one of the most important forces which constrain avian life histories. Availability food affects body condition strongly determines breeding performance. For many small passerines in Northern Hemisphere, lepidopteran larvae (caterpillars) arachnids crucial dietary components during rearing stage, but scarce information is available for Neotropical regions. In this study, we evaluated relationship between delivery rates nestlings caterpillars tree-canopy cover proportion exotic trees nesting insectivorous Masked Gnatcatcher Polioptila dumicola. addition, as high-quality prey-items nestlings, also whether differences these two were associated with nestlings' growth rates. We videotaped 23 nests native forests central-east Argentina 2015–2018 seasons. Both deliveries positively at nest surroundings. Percentage surroundings was low (mean 8.18%), not frequency delivery. The delivered asymptotic values mass nestling tarsus maximum rate. Our results confirm that influenced by surroundings, suggesting less tree-covered patches may contribute a general decrease amount food. conclude diet habitats different degree tree explaining variance performance species. Due alarming alteration recent decades, highlight importance preserving forest portions high tree-cover ensure better austral Gnatcatcher's populations.