Biotic homogenisation in bird communities leads to large‐scale changes in species associations

Abstract

The impact of global change on biodiversity is commonly assessed in terms of changes in species distributions, community richness and community composition. Whether and how much associations between species are also changing is much less documented. In this study, we quantify changes in large-scale patterns of species associations in bird communities in relation to changes in species composition. We use network approaches to build three community-aggregated indices reflecting complementary aspects of species association networks. We characterise the spatio-temporal dynamics of these indices using a large-scale and high-resolution dataset of bird co-abundances of 109 species monitored for 17 years (2001-2017) from 1969 sites across France. We finally test whether spatial and temporal changes in species association networks are related to species homogenisation estimated as the spatio-temporal dynamics of species turnover (β-diversity) and community generalism (community generalisation index). The consistency of these relationships is tested across three main habitats, namely woodland, grassland and human settlements. We document a directional change in association-based indices in response to modifications in species turnover and community generalism in space and time. Weaker associations and sparser networks were related to lower spatial species turnover and higher community generalism, suggesting an overlooked aspect of biotic homogenisation affecting species associations and may also have an impact on species interactions. We report that this overall pattern is not constant across habitats, with opposite relationships between biotic homogenisation and change in species association networks in urban versus forest communities suggesting distinct homogenisation processes. Although species associations contain only partial signatures of species interactions, our study highlights that biotic homogenisation translates to finer changes in community structure by affecting the number, strength and type of species associations.

Quantification and characterisation of commensal wild birds and their interactions with domestic ducks on a free-range farm in southwest France

“…White wagtails are rarely considered in epidemiological studies around poultry farms 6 , 54 , 58 , 59 ; however, the species is much more mobile than Sparrows, both on a daily basis 60 and seasonally, with partial migratory behaviour and winter aggregations in the region of this study 61 . Besides farms, the species is detected in a large diversity of habitats, and it is particularly attracted by wetlands, foraging on open areas along river or lake banks where wild aquatic birds can be present (data from French Breeding Bird Survey 62 ). White wagtails are thus excellent candidates as bridge hosts 16 for pathogens shared between domestic ducks and water birds, such as AIV, as suggested in a previous multi-site study 7 .…”

Land-use intensity influences European tetrapod food-webs

“…Indeed, food-webs sustain a number of ecosystem functions and services, such as pest control (Montoya et al, 2003), seed dispersal (Corlett, 2017), or nutriment cycling in soils (De Vries et al, 2013), and their architecture partly determines community stability (Tylianakis et al, 2010, Saint-Béat et al, 2015, Mestre et al, 2022. We thus urgently need to understand how changes in land use will modify the architecture of food-webs (Li et al, 2018, Rigal et al, 2021. While local studies focusing on specific land uses or taxonomic groups can help formulate hypotheses on how land management intensity affects food-web architecture (Agostini et al, 2020, De Visser et al, 2011, Gossner et al, 2016, Hallmann et al, 2014, Heger et al, 2018, Herbst et al, 2013, we lack a macroecological assessment of these hypotheses and their context-dependence.…”

A large-scale dataset reveals taxonomic and functional specificities of wild bee communities in urban habitats of Western Europe

“…Similar results have been reported for bees, with homogenization of urban pollinator communities compared to rural ones 28 , 45 . Biotic homogenization in urban environments has also been reported for other taxa, for example birds 46 .…”