As global temperatures warm, many species must make adjustments to their range or the timing of life-history events in order to continue to survive and reproduce in a changing world. Some species are considered more vulnerable to these changes, including species native only to islands because their limited range increases the risk to populations from climate events and they have a limited ability to disperse (Taylor et al. 2021). This greatly limits their capacity to adapt to climate change by relocating to a more suitable location with favorable conditions. As such, the only likely way to adapt to climate change for many island-endemic species is through phenotypic plasticity, by which animals alter the timing of life-history events such as reproduction (Taylor et al. 2021).
One such species is the Mauritius kestrel (Falco punctatus). This small bird of prey, native only to the small island of Mauritius in the Indian Ocean, was once the most endangered bird of prey in the world, with a population in the 1970s consisting of only two known breeding pairs, causing a genetic bottleneck where the existing gene pool was extremely limited (Jones et al. 1995). Thanks to repopulation efforts over several decades, the Mauritius kestrel made an incredible recovery and population estimates indicate there are now over 800 individuals (Jones et al. 1995). These birds of prey breed beginning in the dry spring, raising their young as the warm rainy season begins in the early summer (Taylor et al. 2021). But climate change could drastically alter seasonal patterns in Mauritius and put wild populations at risk of declining once more.
A new study published in 2021, however, shows that Mauritius kestrels may have a better chance of adapting to climate change than previously believed. Taylor et al. (2021) tracked rainfall patterns and breeding phenology of Mauritius kestrels between 1962 and 2016, along with other measures of breeding success. Between 1994 and 2014, the study found that the first egg-laying date advanced by about 0.7 days per year, influenced primarily by the mean temperature in the three-month period of July-September (Taylor et al. 2021). Additionally, Taylor et al. (2021) found that overlap of the rainy season with the breeding period had a negative impact on breeding success, favoring earlier breeding. Despite having experienced near-total extinction and an extremely limited gene pool, the population has retained phenological responses that are sufficient for it to track these environmental changes and adapt (Taylor et al. 2021). The Mauritius kestrel demonstrates phenotypic plasticity by adjusting its breeding period as temperatures increase, which may allow it to better adapt to changing environmental conditions despite being an island species that are considered to be more vulnerable to these same changes.
Taylor J, Nicoll MAC, Black E, Wainwright CM, Jones CG, Tatayah V, Vidale PL and Norris K. (2021). Phenological tracking of a seasonal climate window in a recovering tropical island bird species. Climatic Change 164:n.p.
Jones CG, Heck W, Lewis RE, Mungroo Y, Slade G and Cade T. (1995). The restoration of the Mauritius Kestrel Falco punctatus population. IBIS 137:173-180.
The Peregrine Fund. (n.d.). Mauritius Kestrel. Retrieved 5 March 2022 from https://www.peregrinefund.org/explore-raptors-species/falcons/mauritius-kestrel.