Composition, richness and nestedness of gallery forest bird assemblages in an Amazonian savanna landscape: lessons for conservation

Gallery forests are important to the maintenance of a substantial portion of the biodiversity in neotropical savanna regions, but management guidelines specific to this forest type are limited. Here, we use birds as study group to assess if: (1) functional traits can predict the abundance and occupancy of forest species within a savanna landscape, (2) habitat structures influence the taxonomic, functional, and phylogenetic diversity of forest assemblages, and (3) less diverse gallery forest assemblages are a nested subset of more diverse assemblages living near continuous forests. Then, we propose strategies on how gallery forests can be managed to maintain their species assemblages amidst the fast expansion of human activities across tropical savanna landscapes. We studied 26 sites of gallery forests in an Amazonian savanna landscape and found that: (1) habitat specificity is the only functional trait that predicts species abundance and occupancy across a landscape; (2) phylogenetic diversity is negatively correlated with understory foliage density; (3) the percentage of forests and savannas around sites is positively correlated with both phylogenetic and functional diversity; (4) increasing human activities around gallery forest negatively influences taxonomic and functional diversity; and (5) forest bird assemblages are not distributed at random across the landscape but show a nested pattern caused by selective colonization mediated by habitat filtering. Our combined findings have three implications for the design of conservation strategies for gallery forest bird assemblages. First, maintaining the connectivity between gallery forests and adjacent continuous forests is essential because gallery forest bird assemblages are derived from continuous forest species assemblages. Second, because most species use the savanna matrix to move across the landscape, effectively managing the savanna matrices where gallery forests are embedded is as important to maintaining viable populations of forest bird species as managing the gallery forest themselves. Third, in savanna landscapes planned to be used for agriculture production, protecting gallery forests alone is not enough. Instead, gallery forests should be protected with surrounding savanna buffers to avoid the detrimental effects (edge effects and isolation) of human activities on their biodiversity.

Seasonal dynamics of bird assemblages in commercial plantations of Pinus radiata in southern-central Chile

Forest plantations are a relatively new environment in Chile, with impacts of different magnitude on different taxa. Birds are one of the taxa mostly used as ecological indicators to evaluate the effect of different types of disturbances, due to their level of specialization in the use of different microhabitats. We assessed the effect of the age of Pinus radiata plantations (2 sites of 8 and 12 years, respectively) and seasonal (three seasons) on the diversity of bird assemblages. The abundance of species from both sites was assessed through acoustic and visual survey records, which were also compared at trophic guild level. Differences were observed at both sites, with higher diversity calculated for Cerro Ñielol (8 years) compared to Rucamanque (12 years). In seasonal terms, diversity was not affected in Cerro Ñielol, while in Rucamanque significant differences were observed during fall. Guild composition of both localities also showed differences, resulting in higher diversity for Cerro Ñielol in most cases. Despite the fact that the younger plantation presented the highest diversity, elements associated with the landscape are discussed, as well as particularities in the use of space by the species.

Combined effects of bird extinctions and introductions in oceanic islands: decreased functional diversity despite increased species richness

Aim: We analyse the functional consequences of the changes in species composition resulting from extinctions and introductions on oceanic island bird assemblages. Specifically, we ask if introduced species have compensated the functional loss resulting from species extinctions. Location: Seventy-four oceanic islands (>100 km2) in the Atlantic, Pacific and Indian Oceans. Time period: Late Holocene. Major taxa studied: Terrestrial and freshwater bird species. Methods: We compiled a species list per island (extinct and extant, native and introduced), and then compiled traits per species. We used single-trait analyses to assess the effects of past species extinctions and introductions on functional composition. Then, we used probabilistic hypervolumes in trait space to calculate functional richness and evenness of original versus present avifaunas of each island (and net change), and to estimate functional originality of extinct and introduced species. Results: The net effects of extinctions and introductions were: an increase in average species richness per island (alpha diversity), yet a decline in diversity across all islands (gamma diversity); an average increase in the prevalence of most functional traits (23 out of 35) yet an average decline functional richness and evenness, associated with the fact that extinct species were functionally more original (when compared to extant natives) than introduced species. Main conclusions: Introduced species are on average offsetting (and even surpassing) the losses of extinct species per island in terms of species richness, and they are increasing the prevalence of most functional traits. However, they are not compensating the loss of functional richness due to extinctions. Current island bird assemblages are becoming functionally poorer, having lost original species and being composed of functionally more homogeneous species. This is likely to have cascading repercussions on the functioning of island ecosystems.

Effect of Different Management Techniques on Bird Assemblages on Rice Fields in the Republic of Korea

Many bird species rely on the ecological functions of rice field microhabitats. However, recent intensive practices are causing rice fields to provide fewer suitable habitats. This study examined bird microhabitat usage and the effects of intensive use of chemical substances on it. Eco-friendly and conventional rice fields were surveyed from January 2014 to December 2016, and the species presence, the number of birds, and the location of observed microhabitats were recorded. It was found that shorebirds and herons used more eco-friendly rice paddies with fewer or no chemical substances, while waterfowl used the paddy microhabitat more than the other microhabitats, regardless of the amount of chemical substances used. It was confirmed that land birds used ditches or roads in conventional rice fields more than those in fields that used chemical substances. Chemical substances affected bird assemblages differently. Consequently, bird assemblages used habitats differently depending on the farm crop cultivation as well as food abundance. These results provided valuable information useful for managing rice fields that serve as habitats for birds.