A better understanding of species–energy relationships needs to be developed using fine‐grained approaches that involve the use of small geographical scales of known characteristics, such as habitat heterogeneity, food availability, direct measures of temperature, and functional groups of species. We carried out a 2‐year study to analyze the effects of the thermal environment and food availability, while controlling for the influence of habitat structure, on winter species richness of birds living in oakwoods of a mountanious region of Central Spain of Mediterranean continental climate. The guild of ground‐foraging birds was selected as model organisms considering its susceptibility to winter conditions associated with unpredictable snowfalls. The spatial variation in species richness of this guild was determined by food availability, but only for those stable and predictable resources not affected by frequent snowfall (shrubs producing fruits; a complete lack of association was found with arthropod abundance on the ground). Thermal effects associated directly with air temperature, and mediated indirectly by vegetation structure providing a mosaic of sun‐shade patches, were also very influential. These patterns were highly repeatable across years. Daytime temperature had no influence on determining spatial variation in species richness, but night (minimum) temperature was a very important predictor (explained considering the lower temperatures at night, the longer duration of night, and the inability of diurnal birds to develop active behavioral thermoregulation during nighttime). This result highlights the need to consider physiological processes mediating species–environment relationships when analyzing the relationship between climatic variables and biodiversity phenomena.

Forecasting the impact of future global warming on biodiversity requires understanding how temperature limits the distribution of species. Here we rely on Liebig's Law of Minimum to estimate the effect of temperature on the maximum potential abundance that a species can attain at a certain location. We develop 95%-quantile regressions to model the influence of effective temperature sum on the maximum potential abundance of 25 common understory plant species of Finland, along 868 nationwide plots sampled in 1985. Fifteen of these species showed a significant response to temperature sum that was consistent in temperature-only models and in all-predictors models, which also included cumulative precipitation, soil texture, soil fertility, tree species and stand maturity as predictors. For species with significant and consistent responses to temperature, we forecasted potential shifts in abundance for the period 2041-2070 under the IPCC A1B emission scenario using temperature-only models. We predict major potential changes in abundance and average northward distribution shifts of 6-8 km yr −1 . Our results emphasize inter-specific differences in the impact of global warming on the understory layer of boreal forests. Species in all functional groups from dwarf shrubs, herbs and grasses to bryophytes and lichens showed significant responses to temperature, while temperature did not limit the abundance of 10 species. We discuss the interest of modelling the 'maximum potential abundance' to deal with the uncertainty in the predictions of realized abundances associated to the effect of environmental factors not accounted for and to dispersal limitations of species, among others. We believe this concept has a promising and unexplored potential to forecast the impact of specific drivers of global change under future scenarios.

In winter, foraging activity is intended to optimize food search while minimizing both thermoregulation costs and predation risk. Here we quantify the relative importance of thermoregulation and predation in foraging patch selection of woodland birds wintering in a Mediterranean montane forest. Specifically, we account for thermoregulation benefits related to temperature, and predation risk associated with both illumination of the feeding patch and distance to the nearest refuge provided by vegetation. We measured the amount of time that 38 marked individual birds belonging to five small passerine species spent foraging at artificial feeders. Feeders were located in forest patches that vary in distance to protective cover and exposure to sun radiation; temperature and illumination were registered locally by data loggers. Our results support the influence of both thermoregulation benefits and predation costs on feeding patch choice. The influence of distance to refuge (negative relationship) was nearly three times higher than that of temperature (positive relationship) in determining total foraging time spent at a patch. Light intensity had a negligible and no significant effect. This pattern was generalizable among species and individuals within species, and highlights the preponderance of latent predation risk over thermoregulation benefits on foraging decisions of birds wintering in temperate Mediterranean forests.

Brazilian indigenous lands prevent the deforestation of the Amazon rainforest while protecting the land rights of indigenous peoples. However, they are at risk because they overlap with large areas of registered interest for mining. Indigenous lands have been in the spotlight of the pro-development wing of the parliament for decades, and the current president of Brazil, Jair Bolsonaro, promised that he would open up these territories for exploitation. Recently, bill PL191/2020 was released to downgrade the protection status of indigenous lands by regulating mining activities in these territories. Mining operations have an unavoidable socio-environmental impact on indigenous communities that is difficult to compensate. First, rapid demographic growth associated with the incoming migrant workforce often causes social disruption and threat indigenous societies. Moreover, sustained pollution related to mining procedures and accidental spills largely degrade the environment and imperil indigenous health. Finally, mining operations drive deforestation both within and beyond their operational boundaries. Mining is already an essential determinant of forest loss in the Amazon, where further deforestation may result in extended droughts with significant social and economic consequences. We conclude that, if mining operations were allowed in Brazilian indigenous lands, indigenous peoples would be imperiled along with regional and global climate and economies.

No abstract

The strong season‐to‐season variation (seasonality) in abiotic factors and productivity shape the changing patterns of species distribution and diversity throughout the year in temperate ecosystems. However, the determinants of seasonal changes within animal communities have rarely been explored, and the prognosis of community variation typically relies on identifying simple factors (e.g., mean temperature) that are assumed to have a constant effect throughout the year. Here we analyze the competing and changing roles of biotic (vegetation structure and phenology) and abiotic (temperature and elevation) factors in determining the richness and nestedness of montane Mediterranean oakwoods (central Spain) bird species in winter and spring. In winter, the most energy‐demanding period, birds prefer mature forests with higher nocturnal temperatures where they can minimize thermoregulation costs during the long winter nights. In spring, which is the breeding season, spatial variation of species richness and nestedness is more deterministic than in winter. Breeding birds prefer lower forests with cooler temperatures at midday (presumably to avoid summer overheating stress), less unpredictable weather, and where trees develop leaves earlier (suggesting that birds, particularly those that prey on folivorous insects, would be able to breed early in the season). Thus, although both biotic and abiotic factors take part in the assemblage of local communities, the intervening specific components vary between seasons. For example, temperature—the factor most widely used to forecast future community changes—had opposite effects in winter than in spring. These results highlight the importance of fine‐grained scale studies in accounting for temporal variation to understand both current and future regional biodiversity patterns.

Although energy is a major driver of global patterns of biodiversity and species distribution, the test of species-energy relationships needs further development using fine-grained approaches involving different functional groups of species and small geographical scales of known characteristics (habitat heterogeneity, food availability, direct measures of temperature). We carried out an experiment over a broad range of habitat structure and environmental conditions to disentangle the effects of two different energy measures on the small-scale variation of habitat use in winter: one directly related to food resources (manipulated food availability with artificial feeders), and another related to thermoregulatory costs (night temperature). The spatial variation in abundance of a guild of tree-gleaning birds wintering in montane Mediterranean oakwoods of Central Spain was positively related to both components of energy availability (temperature and food resources), even in these mild Mediterranean montane forest of southern Europe. Spatial variation in consumption of food from artificial feeders was negatively related to spatial variation in temperature. The influence of food availability on bird abundance was mediated by vegetation structure, with a lower influence in maturer oakwoods. This study highlights the important role of the energy-related factors, over habitat structure, in determining winter abundance of the studied tree-gleaning guild.

Background. The availability of environmental energy, as measured by temperature, is expected to limit the abundance and distribution of endotherms wintering at temperate latitudes. A prediction of this hypothesis is that birds should attain their highest abundances in warmer areas. However, there may be a spatial mismatch between species preferred habitats and species preferred temperatures, so some species might end-up wintering in sub-optimal thermal environments.Methods. We model the influence of minimum winter temperature on the relative abundance of 106 terrestrial bird species wintering in peninsular Spain, at 10 ×10 km2 resolution, using 95%-quantile regressions. We analyze general trends across species on the shape of the response curves, the environmental preferred temperature (at which the species abundance is maximized), the mean temperature in the area of distribution and the thermal breadth (area under the abundance-temperature curve).Results. Temperature explains a low proportion of variation in abundance. The most significant effect is on limiting the maximum potential abundance of species. Considering this upper-limit response, there is a large interspecific variability on the thermal preferences and specialization of species. Overall, there is a preponderance of positive relationships between species abundance and temperature; on average, species attain their maximum abundances in areas 1.9 °C warmer than the average temperature available in peninsular Spain. The mean temperature in the area of distribution is lower than the thermal preferences of the species.Discussion. Many species prefer the warmest areas to overwinter, which suggests that temperature imposes important restrictions to birds wintering in the Iberian Peninsula. However, one third of species overwinter in locations colder than their thermal preferences, probably reflecting the interaction between habitat and thermal requirements. There is a high inter-specific variation in the versatility of species using the available thermal space, and the limited effect of temperature highlights the role of other environmental factors determining species abundance.