Limited increase in asynchrony between the onset of spring green-up and the arrival of a long-distance migratory bird

Radar-measured passerine vertical speeds reveal a migratory switch near a major barrier

Successful accomplishment of long-distance migration necessitates optimal decision-making processes. Throughout their migration, birds need to constantly choose to fly or to stop. Passerine migrants integrate internal (e.g., lipid deposition) and external (e.g., prevailing winds) factors resulting in specific departure or landing times. We calculated individual departure and landing timing using vertical-looking radar in the Hula Valley, compiled nightly departure and landing ratios (departure and landing amounts relative to total migration flux), and explored how these are affected by meteorological conditions. Crosswind direction emerged as a key factor affecting departure and landing decisions during autumn migration in the area. Birds avoided drifting toward the Mediterranean Sea by landing and preferred taking off when winds blew away from the sea. Our findings represent an undescribed migration initiation and termination switch with implications for flight and stopover scheduling. The method extends the scope of aeroecological research for addressing individual-level migration behavior.

Phenological divergence between plants and animals under climate change

Climate change has altered the timing of recurring biological cycles in both plants and animals. Phenological changes may be unequal within and among trophic levels, potentially impacting the intricate interactions that regulate ecosystem functioning. Here we compile and analyse a global dataset of terrestrial phenological observations, including nearly half a million time series for both plants and animals. Our analysis reveals an increasing phenological asynchronization between plants and animals from 1981 to 2020, with a stronger overall advancement of late-season phenophases for plants than for animals. Almost 30% of temporal variations in plant phenophases can be explained by the timing of the preceding phenophases. This temporal dependency allows the advancement caused by warming to accumulate and propagate through seasons, advancing later phenophases more than earlier phases. By contrast, animals rely on various environmental cues and resource-tracking strategies to initiate their life-cycle activities, which weakens their cross-phenophase linkage and undermines the effect of warming. Our results suggest that future warming may increase phenological asynchronization between plants and animals and potentially disturb trophic interactions and ecosystem stability.

Spatially heterogeneous shifts in vegetation phenology induced by climate change threaten the integrity of the avian migration network

Phenological responses to climate change frequently vary among trophic levels, which can result in increasing asynchrony between the peak energy requirements of consumers and the availability of resources. Migratory birds use multiple habitats with seasonal food resources along migration flyways. Spatially heterogeneous climate change could cause the phenology of food availability along the migration flyway to become desynchronized. Such heterogeneous shifts in food phenology could pose a challenge to migratory birds by reducing their opportunity for food availability along the migration path and consequently influencing their survival and reproduction. We develop a novel graph-based approach to quantify this problem and deploy it to evaluate the condition of the heterogeneous shifts in vegetation phenology for 16 migratory herbivorous waterfowl species in Asia. We show that climate change-induced heterogeneous shifts in vegetation phenology could cause a 12% loss of migration network integrity on average across all study species. Species that winter at relatively lower latitudes are subjected to a higher loss of integrity in their migration network. These findings highlight the susceptibility of migratory species to climate change. Our proposed methodological framework could be applied to migratory species in general to yield an accurate assessment of the exposure under climate change and help to identify actions for biodiversity conservation in the face of climate-related risks.

Morphological Variation and Its Environmental Correlates in the Taihangshan Swelled-Vented Frog across the Qinling Mountains

Simple Summary

Amphibians have weak dispersal abilities and are sensitive to environmental changes, resulting in their disproportionately high risk of extinction, with many species’ populations rapidly declining. Therefore, it is critical for amphibian conservation to understand their adaptive potential by exploring how amphibians respond to environmental changes based on morphological variations. Our results showed that morphological traits of Feirana taihangnica significantly differed among ages. Along with the increase in annual mean temperature, snout-vent length showed an anti-hump trend, indicating no support for Bergmann’s rule. Mean ultraviolet-B of the highest and lowest months were positively and negatively correlated with head width, thigh length and tibia width, respectively. The present study can help understand the effects of environmental changes on morphological variations of this mountain frog species and its adaptive potential, providing important implications for species conservation.

Abstract

The Taihangshan swelled-vented frog (Feirana taihangnica), an endemic species to the Qinling Mountains, central China, has experienced a dramatic population decline over the last few decades. The aim of this work was to quantify morphological variation in F. taihangnica across the Qinling Mountains and examine environmental correlates of this variation of morphological traits. We implemented a hierarchical partitioning to estimate the independent contribution of each environmental variable on morphological variations. Temperature seasonality was the greatest contributor in variations of snout-vent length (SVL) and head width, and ultraviolet-B (UV-B) radiation of the lowest month was the most influential on both thigh length and tibia width. Then, we used generalized additive models to analyze the relationship between each environmental factor and morphological trait variations. Along the increasing of annual mean temperature, SVL decreased firstly and then increased, indicating no support for Bergmann’s rule. Furthermore, SVL was negatively correlated with annual precipitation, while positively with temperature seasonality. The mean UV-B of the highest and lowest months was positively and negatively correlated with head width, thigh length and tibia width, respectively. The results of this study help us to understand adaptive potential of this mountain frog species via morphological variations in the light of environmental changes.