Insights on the functional composition of specialist and generalist birds throughout continuous and fragmented forests

Abstract

A decline in species number often occurs after forest fragmentation and habitat loss, which usually results in the loss of ecological functions and a reduction in functional diversity in the forest fragments. However, it is uncertain whether these lost ecological functions are consistently maintained throughout continuous forests, and so the importance of these functions in continuous forests remains unknown. Point counts were used to assess both the taxonomic and functional diversity of specialist and generalist birds from sampling in a continuous primary forest compared with forest fragments in order to investigate the responses of these groups to forest fragmentation. We also measured alpha and beta diversity. The responses of specialists and generalists were similar when we assessed all bird species but were different when only passerines were considered. When examining passerines we found lower total taxonomic beta diversity for specialists than for generalists in the continuous forest, while taxonomic beta diversity was higher in the fragmented forest and similar between bird groups. However, total functional beta‐diversity values indicated clearly higher trait regularity in continuous forest for specialists and higher trait regularity in fragments for generalists. Specialists showed significantly higher functional alpha diversity in comparison with generalists in the continuous forest, while both groups showed similar values in fragments. In passerines, species richness and alpha functional diversity of both specialist and generalist were explained by forest connectivity; but, only fragment size explained those parameters for specialist passerines. We suggest that considering subsets of the community with high similarity among species, as passerines, provides a better tool for understanding responses to forest fragmentation. Due to the regularity of specialists in continuous forest, their lost could highly affect functionality in forest fragments.

Contrasting Responses of Alien and Ancient Forest Indicator Plant Species to Fragmentation Process in the Temperate Lowland Forests

“…Our results confirm that forest fragment size affects plant community composition besides other taxa such as beetles [ 32 ], birds [ 33 , 34 ], small mammals [ 35 ], and others. Larger forest fragments contain higher richness and a higher proportion of AFI per unit area, compared to smaller forest fragments, while there are fewer alien plants.…”

Influence of habitat type and distance from source area on bird taxonomic and functional diversity in a Neotropical megacity

“…These findings support our first prediction that protected large native forests (source area) are important for the preservation of the most diverse ecological niches and resources in an urbanized landscape. This is essential for the maintenance of high species diversity (Maseko et al 2019), including the Atlantic Forest endemic and specialist bird species pool (Tonetti et al 2017;Schunck et al 2019), as well as diverse ecosystem functions (Anjos et al 2019). Although urban parks provided significant intermediate vegetation structure, compared to source areas and high dwelling density sites they failed to shelter several endemic and habitat, breeding, feeding, and foraging strata specialist birds, in addition to migratory species.…”

Nest density ofAtta sexdens(Linnaeus, 1758) in Atlantic Forest restoration sites depends on the surrounding landscape

“…Lima (2018) registered Dasypus novemcinctus Linnaeus, 1758, nine-banded armadillo, which was considered abundant; Euphractus sexcinctus Linnaeus, 1758, six-banded armadillo and Tamandua tetradactyla Linnaeus, 1758, lesser anteater, both less abundant, both in forest fragments and adjacent restoration sites. Finally, among birds, there are insectivore and omnivore species that use the matrix for foraging (Anjos et al 2019). In a study in the same region and including some of the restoration sites sampled in this study, Santos Jr et al (2016) suggest that, at least until they reach 12 to 15 years of age, restoration sites support only open area or generalist forest bird species.…”

“…Still, the top-down control, exerted mainly by insectivores and parasites, may also have been relaxed in isolated restoration sites. Many groups of organisms that affect ants have their populations decreased in fragmented habitats, including mammals (Rao 2000), insectivore birds (Anjos et al 2019) and parasite insects (Almeida et al 2008, Barrera et al 2017. This reduction in abundance may occur through habitat loss (Barrera et al 2017, due to the influence of edge effects (Almeida et al 2008) or less permeable matrices (Anjos et al 2019).…”