Escudero, E. | bioRxiv Science

bioRxiv2026

Sex- and age-specific body condition decline under warmer and drier breeding conditions in European robins

O_LILocal environmental conditions during the breeding season can limit bird populations. Identifying which variables, when, and how they affect key biological traits such as body condition is crucial for understanding long-term population trends under ongoing climate change. C_LIO_LIWe analysed the relationships between environmental variables and body condition during the breeding season in European robins (Erithacus rubecula), aiming to uncover links between short-term environmental influences and long-term trends in body condition in the context of local climate change. C_LIO_LIUsing data from a robin population monitored between 2007 and 2021, we applied weather sliding-window analyses to identify periods when temperature, soil moisture, and vegetation productivity best predicted individual body condition. For each variable, we identified critical time windows (CTWs) influencing (1) body condition across the season and (2) individual changes within two weeks. Juveniles and adults were analysed separately, with adult males and females distinguished during pre- and post-fledging periods. We also assessed long-term trends in environmental variables and body condition, and examined how body condition was correlated with apparent survival. C_LIO_LIBody condition variation across the season was explained by different environmental variables depending on age, sex, and period. Body condition declined with increasing minimum temperatures in adult males and juveniles, and with low soil moisture in adults of both sexes. We did not identify reliable CTWs explaining short-term within-individual changes in body condition. Across 2007-2021, body condition in adult males during the post-fledging period declined with rising minimum temperatures, while fledging dates advanced. Apparent survival was positively associated with body condition only in juvenile robins. C_LIO_LIOur results reveal multiple seasonal environmental influences that may contribute to short- and long-term declines in body condition in European robins, with effects particularly strong (or most detectable) in adult males. Reduced body condition may have demographic consequences by lowering juvenile survival, although shifts in breeding phenology could mitigate this impact. Overall, these findings highlight how environmental effects on body condition can shape long-term population trends and species vulnerability to climate change. C_LI

ecology↗

bioRxiv2023

Let there be nightlights: the ecological role of bioluminescence in a Costa Rican mushroom

Both marine and terrestrial organisms produce light enzymatically in a process called bioluminescence. Though the ecological role of light production is known for some species, such as fireflies and bacteria, the ecological role in mushroom-producing fungi remains relatively unexplored, particularly in Central America. Here, we discovered a bioluminescent mushroom in the high-elevation oak forests of Costa Rica. We developed mushroom models with Light-Emitting Diodes (LEDs) producing various colors: green, blue, red, and yellow. Over three consecutive evenings after sunset, we applied Tanglefoot invertebrate-trapping glue to both mushroom models and actual mushrooms, and collected the traps before sunrise, then identified the trapped invertebrates to Order. We found green LED traps attracted more invertebrates than non-lit control traps, suggesting that light functions to attract invertebrates. The majority of invertebrates attracted to the green lights were Dipteran flies, who would be capable of dispersing fungal spores. The higher-intensity green LEDs attracted more total invertebrates than the dimmer mushrooms, but the results were not significant. Though we predicted that the invertebrate assemblages attracted to green lights would be similar to the invertebrate assemblage attracted to actual mushrooms, the results were not significant. Similarly, the red, blue, and yellow LEDs attracted fewer invertebrates than the green LEDs, but the differences in community composition were not statistically significant. Our findings corroborate other similar studies in tropical regions that found bioluminescent mushrooms may attract invertebrates.

ecology↗