Biology subjects

Schille, L.

Publications and source records attributed to Schille, L..

6 recordsLinked to original sources

bioRxiv2026

Urbanization drives dietary specialization in insectivorous bird communities: insights from a multi-prey cafeteria experiment monitored by innovative cameras

1. Urbanization is widely associated with functional homogenization of ecological communities, including declines in insectivorous bird species and concomitant restructuring of arthropod assemblages. While these changes are often assumed to alter ecosystem functioning through trophic interactions, it remains unclear whether bird insectivory in cities can be inferred from community composition alone, or whether it also depends on which species actively forage, on natural prey availability and on the arthropod guilds exploited. 2. We hypothesized that urbanization (i) restructures both insectivorous bird communities and arthropod prey assemblages, thereby (ii) increasing divergence between trait-based potential and realized insectivory, while (iii) prey use is shaped by natural prey availability and active prey selection. 3. We used 25 plots distributed along a controlled urbanization gradient in Montreal, Canada. We combined acoustic monitoring of insectivorous bird communities, arthropod surveys, and camera-monitored cafeteria-like experiments deployed on 73 trees to quantify trait-based potential insectivory, realized insectivory through direct foraging interactions, natural prey availability and prey selection among three arthropod guilds (lepidopteran larvae, spiders and ants). 4. Urbanization reduced bird functional diversity while also decreasing the availability of high-quality prey, particularly lepidopteran larvae and spiders. Realized insectivory was consistently decoupled from community-based expectations, with actively foraging assemblages systematically less insect-specialized than predicted by broader community compositions (potential insectivory). This mismatch was non-random and only weakly related to urban and vegetation gradients. Prey use was largely independent of natural prey availability and instead reflected consistent preferences for larval prey over other guilds, with some indication that the functional composition of bird foraging assemblages further shaped which prey were exploited. 5. Our results show that realized trophic interactions emerge through successive ecological filters rather than directly from community composition: environmental conditions restructure bird communities and prey availability, subsequent foraging filters determine which species actively participate, and prey selection governs which guilds are consumed. Predicting ecosystem functioning in cities therefore requires considering not only biodiversity patterns but also the ecological processes linking community composition to realized trophic interactions.

ecology↗

bioRxiv2026

Montreal Urban Observatory: research platform to monitor urban forest ecosystems for global change adaptation and health

As urban populations grow, cities are increasingly seen not only as drivers of climate change but also as critical arenas for implementing mitigation and adaptation strategies. Urban forests and green infrastructure play a vital role in shaping environmental quality and human health, yet access to these benefits remains inequitable. The Montreal Urban Observatory was designed to investigate the complex relationships among biodiversity, ecosystem functioning, and human health. Twenty-five permanent plots were established across the Island of Montreal, strategically located along gradients in vegetation cover, population density, and mean household income. Interdisciplinary research within the Observatory focuses on themes including urban forest structure and function, abiotic conditions, biodiversity, ecological interactions, natures contributions to people, related human health outcomes, and developing novel methodological approaches. The Observatory supports long-term, cross-scale monitoring and fosters collaborative research on urban social-ecological systems, thus contributing to global initiatives to enhance urban sustainability and equity through nature-based solutions. Early results confirm the relevance of the main gradients for several organisms and response variables, from microbes to trees and abiotic factors. For example, sampling all trees, public and private, within a radius of 200m centered on each plot revealed significant differences in the diversity and structure of private and public trees, including an overwhelming dominance of Thuya occidentalis not captured in commonly used public tree inventories.

ecology↗

bioRxiv2024

Urban tree diversity fosters bird insectivory despite a loss in bird diversity with urbanization

Urbanization is one of the main drivers of biotic homogenization in bird communities worldwide. Yet, only a few studies have addressed its functional consequences on the top-down control birds exert on insect herbivores. We hypothesized that their inconsistent results reflect the overlooked heterogeneity of the urban habitat for birds, and in particular the distribution and diversity of urban trees. We monitored tree diversity, bird diversity, avian predation attempts on artificial prey, and the effect of bird exclusion on insect herbivory in 97 trees distributed among 24 urban experimental plots in the city of Montreal, Canada. We characterized urbanization levels through a combination of variables related to tree density, impervious surfaces, anthropic noise, and human population density. Bird diversity decreased with increasing urbanization, whereas the frequency of generalist synurbic species increased. We found no significant relationship between predation and urbanization or between predation and bird diversity. However, tree diversity was positively correlated with predation attempts on artificial prey, irrespective of bird diversity. We revealed a mismatch between the effects of urbanization on bird diversity and on the regulation service and unraveled the functional importance of tree diversity in shaping the avian predation function in urban ecosystems. Our study advocates for the consideration of intra-urban heterogeneity in the investigation of trophic cascades within cities.

ecology↗

bioRxiv2023

Assessing the potential of BirdNET to infer European bird communities from large-scale ecoacoustic data

O_LIPassive acoustic monitoring has become increasingly popular as a practical and cost-effective way of obtaining highly reliable acoustic data in ecological research projects. Increased ease of collecting these data means that, currently, the main bottleneck in ecoacoustic monitoring projects is often the time required for the manual analysis of passively collected recordings. In this study we evaluate the potential and current limitations of BirdNET-Analyzer v2.4, the most advanced and generic deep learning algorithm for bird recognition to date, as a tool to assess bird community composition through the automated analysis of large-scale ecoacoustic data. C_LIO_LITo this end, we study 3 acoustic datasets comprising a total of 629 environmental soundscapes collected in 194 different sites spread across a 19{degrees} latitude span in Europe. We analyze these recordings both with BirdNET and by manual listening by local expert birders, and we then compare the results obtained through the two methods to evaluate the performance of the algorithm both at the level of each single vocalization and for entire recording sequences (1, 5 or 10 min). C_LIO_LIOur analyses reveal that BirdNET identifications can be highly reliable if a sufficiently high minimum confidence threshold is used. However, the current recall of the algorithm is markedly low when the minimum confidence threshold is adjusted to ensure high levels of precision. Thus, we found that F1-scores remain moderate (<0.5) for all datasets and confidence thresholds studied. We therefore estimate that acoustic datasets of extended duration are currently necessary for BirdNET to provide a reliable and minimally comprehensive picture of the target bird community. Our results also suggest that BirdNET performance is not significantly influenced by the type of recorder used or the habitat recorded but is modulated by the volume of species-specific acoustic data available online. C_LIO_LIWe conclude that a judicious use of AI-based IDs provided by BirdNET can represent a novel and powerful method to assist in the assessment of bird community composition through the automated analysis of large-scale ecoacoustic data. Finally, we provide best use recommendations to ensure optimal results from the algorithm for the ecological study of bird communities. C_LI

ecology↗

bioRxiv2022

Impact of early insect herbivory on the invasive oak lace bug (Corythucha arcuata Say, 1832) in different oak species

Insect herbivores co-occurring on the same host plant interact in various ways. In particular, early-season insect herbivory triggers a wide range of plant responses that can determine the performance of herbivores colonizing the plant later in the course of the season. But the strength and direction of such effects are debated, and virtually unknown in the case of novel interactions involving exotic insects in their introduction range. We conducted an observational field study in SW France, a region recently invaded by the Oak Lace Bug (OLB, Corythucha arcuata Say). We measured early chewing damage and subsequent OLB damage in four oak species (Quercus robur, Q. pubescens, Q. cerris and Q. ilex). We set up a complementary non-choice experiment in the laboratory, feeding OLB with leaves with or without prior herbivory. The four oak species differed in their sensitivity to OLB damage, Q. ilex being broadly resistant. Prior herbivory promoted OLB damage in the laboratory experiment, but not in the field. However, prior herbivory did not alter the rank of oak resistance to the OLB. Our results suggest possible synergistic effects between spring defoliators and the OLB. This study brings insight into herbivore-herbivore interactions and their possible implications for forest management.

ecology↗

bioRxiv2020

Host-mediated, cross-generational intraspecific competition in a multivoltine herbivore species

AO_SCPLOWBSTRACTC_SCPLOWConspecific insect herbivores co-occurring on the same host plant interact both directly through interference competition and indirectly through exploitative competition, plant-mediated interactions and enemy-mediated interactions. However, the situation is less clear when the interactions between conspecific insect herbivores are separated in time within the same growing season, as it is the case for multivoltine species. We hypothesized that early season herbivory would result in reduced egg laying and reduced performance of the next generation of herbivores on previously attacked plants. We tested this hypothesis in a choice experiment with box tree moth females (Cydalima perspectalis Walker, Lepidoptera: Crambidae). These females were exposed to box trees (Buxus sempervirens L., Buxaceae) that were either undamaged or attacked by conspecific larvae earlier in the season. We then compared the performance of the next generation larvae on previously damaged vs undamaged plants. Previous herbivory had no effect on oviposition behaviour, but the weight of next generation larvae was significantly lower in previously damaged plants. There was a negative correlation between the number of egg clutches laid on plants by the first generation and the performance of the next generation larvae. Overall, our findings reveal that early season herbivory reduces the performance of conspecific individuals on the same host plant later in the growing season, and that this time-lagged intraspecific competition results from a mismatch between the oviposition preference of females and the performance of its offspring.

ecology↗