Biology subjects

Barba, E.

Publications and source records attributed to Barba, E..

4 recordsLinked to original sources

bioRxiv2024

Continent-wide drivers of spatial synchrony in age structure across wild great tit populations

Spatio-temporal variation in age structure influences population dynamics, yet we have limited understanding of the spatial scale at which its fluctuations are synchronised between populations. Using 32 great tit populations, spanning 3200km and >130,000 birds across 67 years, we quantify spatial synchrony in breeding age structure and its drivers. We show that larger clutch sizes, colder winters and summers, and larger beech crops lead to younger populations. We report distant-dependent spatial synchrony of age structure, which is maintained at approximately 650km. Despite covariation with age structure, reproductive and environmental variables do not influence the scale of synchrony, except for a moderate effect of beech masting. We suggest that local ecological and density-dependent dynamics impact how environmental variation interacts with age structure, influencing estimates of the environments effect on spatial synchrony. Our analyses demonstrate the operation of synchrony in age structure over large scales, with implications for age-dependent demography in populations.

ecology↗

bioRxiv2024

Research disturbance negatively impacts incubation behaviour of female Great Tits

Human-induced disturbance is perceived by avian species as a predation risk. However, the anti-predatory behaviour triggered by these non-lethal events can have negative impacts on reproduction and offspring survival. Research on breeding birds often involves visits to their nests and is likely to disrupt parental behaviour, but nest visits that do not involve direct handling of females have been overlooked as important disturbance events. This study focuses on the impacts of short visits to the nest of incubating Great tit (Parus major) females. We investigated how long they stay away from the nest (off-bout) after a disturbance, their possible compensatory behaviour once they resume incubation (on-bout), and the effects on daily incubation rhythms. We used three years of data from two breeding populations to assess the consequences of disturbances in two scenarios: when the female is present in the nest and flushed, and when the female is absent. We found that after a disturbance, the immediate off-bout was longer when the female was either present or absent, with the magnitude of the disturbance being greater when females were flushed. Females did not compensate with longer on-bouts afterwards, i.e. the research disturbance altered daily incubation behaviour by reducing the total time spent on the nest in relation to the number of daily disturbance events. Females that alter their behaviour in response to perceived predation risk would perform longer incubation periods, resulting in lower hatching rates. These effects of research on female behaviour should be considered when planning field experiments.

animal behavior and cognition↗

bioRxiv2023

Host space, not energy or symbiont size, constrains feather mite abundance across passerine bird species

Comprehending symbiont abundance among host species is a major ecological endeavour, and the metabolic theory of ecology has been proposed to understand what constraints symbiont populations. We parameterized metabolic theory equations to predict how bird species body size and the body size of their feather mites relate to mite abundance according to four potential energy (microbial abundance, uropygial gland size) and space constraints (wing area, number of feather barbs). Predictions were compared with the empirical scaling of feather mite abundance from 26,604 birds of 106 passerine species, using phylogenetic modelling and quantile regression. Feather mite populations were strongly constrained by host space (number of feather barbs) and not energy. Moreover, feather mite species body size was unrelated to their abundance or to the body size of their host species. We discuss the implications of our results for our understanding of the bird-feather mite system and for symbiont abundance in general.

ecology↗

bioRxiv2020

Bird populations most exposed to climate change are less responsive to climatic variation

The phenology of many species shows strong sensitivity to climate change; however, with few large scale intra-specific studies it is unclear how such sensitivity varies over a species range. We document large intra-specific variation in phenological sensitivity to temperature using laying date information from 67 populations of two European songbirds covering a large part of their breeding range. Populations inhabiting deciduous habitats showed stronger phenological sensitivity compared with those in evergreen and mixed habitats. Strikingly, however, the lowest sensitivity was seen in populations that had experienced the greatest change in climate. Therefore, we predict that the strongest phenological advancement will not occur in those populations with the highest sensitivity. Our results show that to effectively assess the impact of climate change on phenology across a species range it will be necessary to account for intra-specific variation in phenological sensitivity, climate change exposure, and the ecological characteristics of a population.

ecology↗