Stratal distribution and resource partitioning of birds in the Knysna Forest, South Africa

Abstract

Habitat subdivision and resource partitioning of the birds of the evergreen high forest of the southern Cape are investigated. Most species utilize a wide stratal range with insectivores predominating in the lower strata and mixed-feeders and frugivores in the upper strata. Members of the respective foraging guilds used a different stratum or were separated by differences in morphology or mass, suggesting different sized prey and limited competition. RCsumCOn etudie la subdivision de l'habitat et la repartition des ressources des oiseaux de la grande for& sempervirente du Cap. La plupart des espkces se rencontrent dans une large bande ou les insectivores predominent au niveau le plus bas, et les omnivores et frugivores, plus haut. Les membres de chaque groupe se repartissaient dans des couches diffkrentes ou etaient caracterises par des differences de morphologie ou de masse, laissant supposer des proies de taille differente et une compktition limitee.

Vertical stratification of an avian community in New Guinean tropical rainforest

“…The increased diversity and abundance of birds towards the canopy may be explained by high fruit and flower availability in the canopy, which is indirectly supported by the increased diversity of frugivorous and omnivorous birds in higher strata. This result is consistent with studies on vertical distribution of trophic guilds from other tropical sites (Terborgh 1980;Greenberg 1981;B e l l1982;Frith 1984;Koen 1988). However, the diversity of frugivores in the understory might be slightly underestimated in our dataset, because mist nets are not designed to capture large frugivorous birds foraging on the ground (e.g., Goura victoria, Casuarius unappendiculatus).…”

“…Insectivorous birds did not exhibit any pattern of vertical distribution of species diversity, although their abundance was slightly higher in the understory. Higher abundance of insectivores in the understory compared with the canopy was also reported from the neotropics (Greenberg 1981) and Africa (Koen 1988). One could expect that the vertical distribution of insectivorous birds may be linked with the abundance and diversity of insects in different strata.…”

“…In general, forests with higher vertical heterogeneity are expected to host more diverse avian communities (MacArthur and MacArthur 1961;Goetz et al 2007;Huang et al 2014). The main assumption of the hypothesis is that stratification of microhabitats allows the coexistence of bird species exploiting the same resources (and thus having similar morphology) due to reduced interference competition (Koen 1988;Styring and bin Hussin 2004;B öhm and Kalko 2009;Kwok 2009). A structurally complex mature tropical forest with high vertical heterogeneity therefore represents a suitable environment to study habitat partitioning within an avian community as a mechanism for maintaining high species diversity (Cody 1974;Schoener 1974).…”

“…A structurally complex mature tropical forest with high vertical heterogeneity therefore represents a suitable environment to study habitat partitioning within an avian community as a mechanism for maintaining high species diversity (Cody 1974;Schoener 1974). Forest bird communities are known to be vertically stratified in terms of species composition (Turček 1951;Dickson and Noble 1978;Terborgh 1980;Koen 1988;B öhm and Kalko 2009) overall abundance (Pearson 1971;Bell 1982) and species diversity (Jayson and Mathew 2003). Therefore, preferences for certain strata can be one of the main factors leading to the separation of avian guilds (Holmes and Recher 1986).…”

Vertical stratification and seasonal changes of the avian community in Mount Cameroon lowland rainforest

“…Conversely, where competition for space or for limited resources occurs, the vertical forest gradient can be an important factor in resource partitioning. Spatial segregation of birds into vertical strata thus allows local coexistence of potentially competing species (Dickson & Noble, 1978; Koen, 1988; Schoener, 1974).…”