Functional response traits and altered ecological niches drive the disassembly of cloud forest bird communities in tropical montane countrysides

Abstract

Anthropogenic disturbance contributes to global change by reshaping the ecological niche space available to biological communities. Quantifying the range of functional response traits required for species persistence is central towards understanding the mechanisms underlying community disassembly in disturbed landscapes. We used intensive field surveys of cloud forest bird communities across seven replicate landscapes undergoing agricultural conversion in the Peruvian Andes to examine how a suite of 16 functional response traits related to morphology, diet, foraging behaviour and environmental niche breadth predict (1) species‐specific abundance changes in countryside habitats compared to forest and (2) differential changes to the ecological niche space occupied by communities. Our analyses relied on (1) hierarchical distance sampling models to examine the functional predictors of abundance change across the agricultural land use gradient while accounting for imperfect detection and (2) n‐dimensional hypervolumes to quantify the expansion and contraction of ecological niche space in countryside habitats. Key traits related to increased abundance in early successional and mixed‐intensity agricultural areas included (1) morphological adaptations to dense understorey habitats, (2) plant‐based diets (flowers, fruit and seeds) and (3) broad elevational range limits and habitat breadth. Species occupying mixed and high‐intensity agricultural land use regimes had mean elevational range limits 20%–60% wider than species found within forests. Collectively, ecological niche space expanded within agricultural habitats for traits related to diet and environmental niche breadth, while contracting for foraging and dispersal traits. Such changes were driven by species with unique functional trait combinations. Our results reveal the dynamic changes to ecological niche space that underly community structure in disturbed landscapes and highlight how increased niche breadth can ameliorate disturbance sensitivity for generalist species. We emphasize that functional traits can be used to predict changes in community structure across disturbance gradients, allowing insights into specific mechanisms underlying community disassembly beyond emergent patterns of functional diversity. By identifying key functional trait groups that align with different countryside habitats, we demonstrate how conservation practitioners can contribute to the retention of avian functional diversity in agricultural landscapes throughout the world.

Sensitivity of tropical montane birds to anthropogenic disturbance and management strategies for their conservation in agricultural landscapes

“…Our results for Andean birds support the idea that species adapted to a broader range of environmental conditions (e.g., large global range sizes and broad elevational ranges) are better adapted to anthropogenic disturbance (Ausprey et al., 2022; Karp et al., 2019). In particular, species declining in high‐intensity agricultural landscapes had smaller elevation ranges than expected given their global range size, meaning that adaptations specifically associated with elevation (e.g., rapid changes in temperature) may pose additional constraints to species persistence (Ceresa et al., 2021; Duclos et al., 2019).…”

Response trait diversity and species asynchrony underlie the diversity–stability relationship in Romanian bird communities

“…Regardless, some of the traits used here may be differently classified elsewhere as new discoveries are made regarding bird effects on ecosystem functioning. For example, though we included beak morphology (length and depth) as effect traits following previous studies (Luck et al, 2012; Wheelwright, 1985), these traits can also impact abundance responses to land cover (Ausprey et al, 2022). Such overlap between response and effect traits further emphasises both the challenge of appropriate trait selection (Mori et al, 2013), and the observation that response diversity can impact effect trait composition and thus ecosystem functioning (de Bello et al, 2021).…”

“…Species with greater diet breadth are likely to be more resistant to environmental change due to their ecological flexibility if their primary food source was reduced(Ausprey et al, 2022;Luck et al, 2012;Schleuning et al, 2020) Foraging plasticity Number of foraging strata used Species that specialise in one foraging behaviour including their foraging strata are unable to adapt to foraging in other strata under environmental change(Luck et al, 2012) …”

Divergent ecological responses to typhoon disturbance revealed via landscape-scale acoustic monitoring

“…In contrast, the forest specialist O. elegans was not detected less frequently after the typhoons, suggesting that its habitat and/or foraging were unaffected by the typhoons, or perhaps that cavity nesting reduced typhoon impact by reducing exposure to extreme weather (Inoue et al, 2019). Such species-specific responses to disturbance may more generally reflect differences in life history and other functional response traits (Suding et al, 2008), which can be useful predictors of community dynamics, disassembly, and stability in birds (e.g., Ausprey et al, 2022;Burivalova et al, 2015;Hordley et al, 2021;Zhang et al, 2016). Similarly, different vocalisation typhoon responses among field sites may reflect differences in underlying vegetative changes as determined by plant functional response traits.…”

“…Such species-specific responses to disturbance may more generally reflect differences in life history and other functional response traits (Suding et al, 2008), which can be useful predictors of community dynamics, disassembly, and stability in birds ( e . g ., Ausprey et al, 2022; Burivalova et al, 2015; Hordley et al, 2021; Zhang et al, 2016). Similarly, different vocalisation typhoon responses among field sites may reflect differences in underlying vegetative changes as determined by plant functional response traits.…”