Microclimate refugia as a dynamic spatiotemporal area in a context of temperature constrain as tested in a threatened grassland bird

The term "climate refugia” is normally associated with areas where species persist during severe climatic change periods. We use, microclimate refugia referring to dynamic spatial-temporal areas species use to cope with elevated temperatures. These areas may enable species to persist in, otherwise, inhospitable landscapes. An example are the semi-natural grasslands, being climate vulnerable hotspots in Europe that host many threatened species.

In this study we i) test if the Vulnerable Little bustard (Tetrax tetrax) (LB) increases use of microclimate refugia with increasing temperatures; ii) assess which environmental features offer microclimate refugia opportunities. GPS data from 77 LB tagged between 2009 and 2019 were associated with land use and hourly temperature information at 30x30m resolution.

50.8% of the locations occurred at temperatures > 25ºC and 6.6% at more than 37ºC, indicating that this species is exposed to temperatures above their physiological thermal optimum. Locations with temperature at least 0.5ºC cooler than the surrounding landscape were defined as providing microclimate refugia. As predicted, LB increased the use of microclimate refugia at higher temperatures. However, less than 25% of the GPS locations provided refugia and LB used these rarely (> 10%). Locations with microclimate refugia occurred more frequently in hotter continental areas, indicating LB use refugia more often in warmer regions of its distribution. Microclimate refugia, used by this species, were areas with high proportion of herbaceous vegetation with small patches of trees and shrubs.

Despite using microclimate refugia in a small proportion, possibly due to life-history and behaviour constraints, these areas may help Little bustards persist in extreme conditions.

[Host: João Paulo Silva, Movement Ecology - MOVE, Biodiversity in Agricultural and Forest Ecosystems - AGRODIV]