Territorial foraging behavior in the male Violet-capped Woodnymph is dependent on the density of patches of inflorescences of Heliconia spathocircinata Aristeg. (Heliconiaceae) in the Brazilian Atlantic forest
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- Missagia, C.C.C. & Alves, M.A.S. Braz. J. Bot (2016) 39: 1145. doi:10.1007/s40415-016-0303-x
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Hummingbirds can vary their foraging strategies by adopting different behavior patterns. In Central America, the territorial behavior of these birds may be influenced by the floral resource availability in patches of Heliconia L. (Heliconiaceae) species. We investigated whether a similar pattern occurs in the South American species, Heliconia spathocircinata Aristeg., in a fragment of Atlantic forest in the state of Rio de Janeiro, Brazil, and whether agonistic interactions between the hummingbirds were correlated with the body weight. We conducted focal observations over two flowering seasons (2011/2012 and 2012/2013) in 159 patches of H. spathocircinata to evaluate whether territorial defense by the hummingbirds depends on floral resource availability (number of inflorescences per patch of 78.5 m2), using a linear regression analysis. This patch area (territory size) was defined arbitrarily, based on the typical size of inflorescence patches found within the study area. The potential relationship between body weight and agonism was evaluated using a Pearson correlation. We recorded 55 different territories defended by Thalurania glaucopis (Gmelin, 1788) in patches containing between eight and 16 inflorescences. The number of times the T. glaucopis males defended their territories was influenced by the number of inflorescences per patch. Agonism was positively correlated with body weight only for intraspecific interactions in T. glaucopis. This indicates that the foraging behavior of the pollinator of the South American H. spathocircinata may be influenced directly by the available number of inflorescences in patches of this plant.