Extreme events are more likely to affect the breeding success of lesser kestrels than average climate change

Abstract

Climate change is predicted to severely impact interactions between prey, predators and habitats. In Southern Europe, within the Mediterranean climate, herbaceous vegetation achieves its maximum growth in middle spring followed by a three-month dry summer, limiting prey availability for insectivorous birds. Lesser kestrels (Falco naumanni) breed in a time-window that matches the nestling-rearing period with the peak abundance of grasshoppers and forecasted climate change may impact reproductive success through changes in prey availability and abundance. We used Normalised Difference Vegetation Index (NDVI) as a surrogate of habitat quality and prey availability to investigate the impacts of forecasted climate change and extreme climatic events on lesser kestrel breeding performance. First, using 14 years of data from 15 colonies in Southwestern Iberia, we linked fledging success and climatic variables with NDVI, and secondly, based on these relationships and according to climatic scenarios for 2050 and 2070, forecasted NDVI and fledging success. Finally, we evaluated how fledging success was influenced by drought events since 2004. Despite predicting a decrease in vegetation greenness in lesser kestrel foraging areas during spring, we found no impacts of predicted gradual rise in temperature and decline in precipitation on their fledging success. Notwithstanding, we found a decrease of 12% in offspring survival associated with drought events, suggesting that a higher frequency of droughts might, in the future, jeopardize the recent recovery of the European population. Here, we show that extreme events, such as droughts, can have more significant impacts on species than gradual climatic changes, especially in regions like the Mediterranean Basin, a biodiversity and climate change hotspot.

Shape-shifting: changing animal morphologies as a response to climatic warming

“…This also highlights that care is needed when using only genetic markers to signify adaptive evolution, and it emphasises the importance of collaborative work that encompasses genetic, heritable, long-term, and short-term studies on morphological change in response to climatic warming. Genetic changes over shorter time frames are often accompanied by extreme selective mortality [87], which is likely to become increasingly common [11] and may accelerate the occurrence of selection [88], but relatively few studies have, to our knowledge, looked at the effect of extreme climate events on the evolution of a species over a longer time scale. The responses being evolutionary, with a genetic basis, or plastic, without such a basis, can be important for predicting how much an animal can change (as reviewed in [89]), but currently there is a lack of studies integrating genetic and morphological changes in response to climatic warming.…”

Early Breeding Conditions Followed by Reduced Breeding Success Despite Timely Arrival in an Alpine Migratory Songbird

“…Right: Year effect on nest success: 65% (0.54-0.76) in 2019 and 51% (0.38-0.64) in 2020, β = -0.139 (0.314-0.040), P = 0.12, N = 126. remote sensing data (MODIS NDSI) of the study area in the Western Alps in Piedmont, we found high interannual variations (Figure 1B), with an average year in 2019 and a very early snow free date in 2020. Direct observations and high-resolution remote sensing data (Sentinel-2) allowed a more detailed quantification of the differences between the 2 years, showing that snowmelt, crucial for clutch initiation (Liebezeit et al, 2014), and greenup of the vegetation, a proxy for food availability (Pettorelli et al, 2006;Marcelino et al, 2020), occurred about 3 weeks earlier in 2020 (Figure 2A). These yearly differences set the scene to compare key phenological events, such as arrival, clutch initiation, date of hatching and fledging, as well as breeding success as a measure of individual and overall population fitness.…”

“…We observed a generally higher variability in breeding phenology in the early spring of 2020, which was found also in McGuire et al (2020), and a delayed hatching. Clutches experiencing a rainy season or severe weather events, such as snow storms, have a prolonged incubation period, exposing the nest to predators for a longer period at the same time, and generally higher failure rates (due to abandonment, hatch failure and predation) than clutches in a dry season (Rauter et al, 2002;Kluen et al, 2011;Higgot et al, 2020;Marcelino et al, 2020). Further explanations for variations in breeding success in alpine birds include annual variations in temperature, where success is lower in years with lower mean temperatures (Mingozzi et al, 2021), but also variations in weather-dependent resources (Barras et al, 2021) and local predation risk (Rauter et al, 2002).…”

Reduced Breeding Success Suggests Trophic Mismatch Despite Timely Arrival in an Alpine Songbird

“…1b), with an average year in 2019 and a very early snow free date in 2020. Direct observations and high-resolution remote sensing data (Sentinel-2) allowed for a more detailed quanti cation of the differences between the two years, showing that snow melt, crucial for the clutch initiation 30 , and greenup of the vegetation, a proxy for food availability 31,32 , occurred about two weeks earlier in 2020 ( Fig. 2a).…”