Reactions of Some Panamanian Birds to Human Intrusion at the Nest

Abstract

Observations on food type, nest type, clutch size and the response of adults and young to a human intruder at their nests were recorded for 17 spp. [Pipra mentalis, Myiozetetes cayanensis, Myiozetetes similis, Muscivora tyrannus, Tyrannus melancholicus, Elaenia chiriquensis, Myiodynastes maculatus, Tachycineta albilinea, Turdus grayi, Vireo olivaceus, Euphonia laniirostris, Tangara inornata, Thraupis palmarum, T. episcopus, Sporophila americana, S. nigricollis, Arremonops conirostris] of passerine birds found in open and edge habitats in the Panama Canal Zone. Statistical analysis revealed significant positive correlations between defecation by the young when handled and proportion of fruit in the diet, clutch size and strength of nest defense by the adult, and concealment of nests and weakness of nest defense. These correlations are interpreted as resulting from the following causal relationships: food type-defecation response, nest type-adult response, and, possibly, clutch size-adult response.