Climate Change and Insectivore Ecology

Abstract

The impacts of climate change on natural populations are only beginning to be understood. Although some important changes are already occurring, in the future these are predicted to be more substantial and of greater ecological significance. Insects are a key taxonomic group for understanding the ecological impacts of climate change, due to their responsiveness to environmental change and importance as food for other organisms. Insects are highly sensitive to rising temperatures, changes in rainfall patterns and erratic weather conditions, driving rapid short‐term variations in their abundance, mobility, distribution and phenology. Such variations represent changes in their availability as prey to insectivores, a diverse range of insect‐eating animals that include mammals, fish, amphibians, reptiles and birds. The impacts of these changes on the ecology of insectivores are complex and include population increases or decreases, broad‐scale shifts in distribution, and changes in behavioural traits such as foraging strategy, investment in parental care, and the timing of breeding and migration. Although some insectivorous species are able to respond to – and even benefit from – climate change, those that fail to respond appropriately may struggle to reproduce, disperse and survive, leading to population decline and ultimately, to extinction. Key Concepts Insects are a key taxonomic group in most terrestrial and freshwater ecosystems, providing an important trophic resource for insectivores. Climate change is already causing major shifts in the distribution, phenology, behaviour, abundance and diversity of insect populations, with complex consequences for insectivores. Climate change may benefit some insectivores by increasing food availability and providing more suitable conditions for reproduction. Specific benefits to insectivores include earlier parturition, faster development of juveniles and range expansion. Warmer temperatures may also cause negative impacts on insectivores, through more frequent and intense heat waves and reduced water availability in arid environments. The negative impacts are expected to be more severe for taxa that are less able to disperse or migrate to escape unfavourable conditions, and thus less able to shift range to track the changing conditions. The timing of biological events (phenology) will be affected – primarily by advancing the dates at which insects become active in spring and extending the length of the active season of insects in temperate and boreal regions. Important gaps in our knowledge remain, for example despite the large biomass and species richness of insects in the tropics the impacts of climate change on tropical insectivores remain largely unknown.

A quantitative synthesis of and predictive framework for studying winter warming effects in reptiles

“…In many regions, mild winters are followed by late cold spells, which can expose individuals close to the surface to tissue damage (Benard 2015 ; Turner and Maclean 2022 ). Reptiles that specialize on invertebrate prey could also face trophic mismatch, as insects are highly sensitive to short-term climatic shifts and have been shown to advance phenologies at faster rates than insectivorous predators (Vafidis et al 2019 and references therein). Finally, premature spring emergence could carry reproductive costs.…”

Heart rate monitoring reveals differential seasonal energetic trade-offs in male noctule bats

“…Animals need energy to survive, grow, move, and reproduce [1], and meeting these daily energy requirements can be challenging. Small changes in environmental conditions can have large effects on fitness [2,3], especially in animals that depend on ephemeral resources [4]. To deal with adverse conditions, animals have evolved manifold and crucial energy-saving strategies [5,6].…”