Landscape and Stand Characteristics Influence on the Bird Assemblage in Nothofagus antarctica Forests of Tierra del Fuego

Abstract

Different variables operate simultaneously at different spatial scales, influencing community composition and species distribution. This knowledge could improve management and conservation practices in managed menaced forests. The objective of this work was to determine the influence of landscape and stand variables on the bird assemblage of the managed Nothofagus antarctica forest of Tierra del Fuego (Argentina). We used data from bird point counts (three or four censuses during middle summer of two consecutive years) located at 48 sites distributed at four ranches. At each site, we extracted landscape variables with Fragstat software from the forest patches, the cover classes, and the whole landscape. We also evaluated local stand characteristics, such as forest structure, ground cover, and food availability, including understory plant cover usually consumed by birds and available arthropods. Data were evaluated by detrended and canonical correspondence analyses. We found that landscape configuration (e.g., forest patch shape) and local stand variables (e.g., canopy cover) influenced bird assemblage more than landscape composition. Moreover, bird functional groups responded differently to different spatial scale variables (e.g., forest specialist species were associated with forest structure, but species that use low strata to nest and feed were associated with landscape configuration variables), demonstrating the importance of using multiple spatial scales to better understand bird species requirements. The combination of practices that promote some local characteristics (e.g., high canopy cover) and more complex landscape configurations could simultaneously favor different bird species groups and improve the effectiveness of management and conservation strategies.

Changes in the bird communities of Nothofagus forests in a long‐term plot in Tierra del Fuego

“…(2015), and Benitez et al. (2019, 2021, Benitez, Barrera, Rosas, et al., 2022; Benitez, Barrera, Sola, et al., 2022). This methodology estimates density with the quantity of observed individuals in a circle area whose radius is half the maximum observation distance (the distance at which the farthest bird was observed in each forest type).…”

“…The specific richness was calculated as the total number of species at each counting point, while the density of passeriform birds was estimated according to the methodological proposal of Lencinas et al (2005) and used in Pastur et al (2015), and Benitez et al (2019, 2021, Benitez, Barrera, Rosas, et al, 2022Benitez, Barrera, Sola, et al, 2022). This methodology estimates density with the quantity of observed individuals in a circle area whose radius is half the maximum observation distance (the distance at which the farthest bird was observed in each forest type).…”

“…Each observation point was re-visited four times during 13 consecutive years (2010-2022) at the beginning of each summer (December). We followed a method successfully applied in these forests (Benitez et al, 2019, Benitez 2021, Benitez, Barrera, Rosas, et al, 2022Benitez, Barrera, Sola, et al, 2022;Lencinas et al, 2009Lencinas et al, , 2018Martínez Pastur et al, 2015), consisting of 2 min habituation (time that birds delay in returning to normal activity, when observations are not registered) and 8 min registration (effective observation). Bird surveys were carried out during the first 4 h after dawn, a period corresponding to most social and feeding bird activities (Deferrari et al, 2001).…”

“…Functional groups also respond diversely depending on the factor influence scale. For example, forest specialist species are associated with forest structure (local scale), but species that use low strata to nest and feed are associated with landscape configuration variables (spatial arrangement of habitat patches within the landscape, e.g., number of forest patches or edge density, Benitez, Barrera, Rosas, et al., 2022). Evaluating natural bird population variation for different local conditions proves mandatory in this context.…”