Influence of body size on coexistence of bird species

Abstract

Theory suggests that body size is an important factor in determining interspecific competition and, ultimately, in structuring ecological communities. However, there is a lack of pragmatic studies linking body size and interspecific competition to patterns in ecological communities. The objective of the present study was to determine the effect of body size (mass) on competitive interactions between bird pairs and to investigate the influence of food guilds. Point-counts were carried out in nine sites every month from November 2002 to November 2003 in the Cuetzalan Region, Mexico, and we used presence/absence and abundance data for the analyses. To calculate the strength of competition we used the Angle Frequency Method to extract form factors from 20 pairwise interactions. A prototype competition interaction and random pairs were also constructed. We used clustering techniques (PCA) to calculate the dissimilarity scores (distances, D) of each of the pairwise interactions to the prototype competition and random pairs and one-way ANOVA to test for differences between the means of the random and competitive pairs. The ratio in body mass (lnBM) for each of the interacting pairs was calculated, and the association between the lnBM ratio and the strength of competition (D) was tested using a Pearson product-moment correlation coefficient. To test for the influence of foraging guilds we used a univariate general linear model. Our results demonstrate a significant negative relationship between bird body mass ratio and competition strength -i.e. competition strength increased when the body masses of the birds became more similar. We did not find a significant influence of foraging guild on the relationship between body mass ratio and competition strength. On the basis of these results, we suggest that high variation in body sizes amongst sympatric species promotes coexistence in communities.

Forest structure affects resource partitioning between pygmy and white-breasted nuthatches

“…Second, white-breasted nuthatches, as the larger species, may deter pygmy nuthatches from foraging on the trunk of larger trees. Body size has long been suspected as a mechanism by which closely related species can coexist (Hutchinson 1959;Leyequién et al 2007). However, pygmy nuthatches are considered the competitively superior species in ponderosa pine forests because they outnumber all other species (Kingery & Ghalambor 2001).…”

Positive Relationships between Association Strength and Phenotypic Similarity Characterize the Assembly of Mixed-Species Bird Flocks Worldwide

“…Both body size and foraging guild have been used extensively in null-model tests of community assembly (Gotelli and Graves 1996;Weiher and Keddy 1999). Body-size similarity of a species pair was calculated as the ratio of the natural logarithms of the body masses of the two species, with the heavier species always being in the denominator (Leyequién et al 2007). All body-mass values were obtained from Dunning (2008).…”

Niche partitioning among three tree-climbing bird species in subtropical mountain forest sites with different human disturbance

“…Numerous studies of avian communities have elucidated differences between similar species inhabiting the same habitat which lead to coexistence (MacArthur 1958, Hutchinson 1961, Alatalo and Alatalo 1979, Leyequién et al 2007, Lara et al 2011, Cloyed 2014. The general view, in the face of interspecific competition, is that the primary way to achieve this coexistence is for species to show a differential use of resources (Hutchinson 1961, Schoener 1974, Pyke 1982, Young et al 2010.…”