Dietary Overlap and Foraging Competition Between Mourning Doves and Eurasian Collared-Doves

Abstract

The recent Eurasian collared-dove (Streptopelia decaocto, hereafter collared-dove) invasion of North America has raised concerns regarding its effects on native species, particularly mourning doves (Zenaida macroura). Our goal was to assess the potential for, and possible consequences of, foraging competition between mourning doves and collared-doves. We compared diet selection and measured degree of dietary overlap between the 2 dove species in a captive cafeteria experiment, and we measured aggression and competitive ability of these species in 3 captive competition experiments. We evaluated the effects of body size, temperature, and food distribution on aggression and competitive ability of both species, and we measured intraspecific aggression levels and competitive ability within each species. We found a high degree of dietary overlap between species; food preferences were similar between species, and Pianka's index of foraging-niche overlap was 0.95. Neither aggression nor competitive ability varied between species, however. Distribution of food in cafeteria experiments did not affect seed-preference results. Ambient temperature and body size of competitors had little effects on aggression or competitive ability of either species. Distribution of food in the environment affected aggression between species, however; aggression was greater in single (0.50 ± 0.10 interactions/min) than in multiple-patch (0.12 ± 0.02 interactions/min) trials. Collared-doves do not appear behaviorally more aggressive or competitively successful than mourning doves. Our results suggest that the potential for negative effects of collared-doves on mourning dove populations may be less than previously suspected, so control measures for collared doves may be unnecessary. However, competitive dynamics involving larger flocks of collared-doves and other potentially limiting resources must be considered.