Quaternary climatic fluctuations and resulting climatically suitable areas for Eurasian owlets.

AIM

The nested pattern in the geographical distribution of three Indian owlets, resulting in a gradient of endemicity, is hypothesized to be an impact of historical climate change. In current time, the Forest Owlet is endemic to central India, and its range is encompassed within the ranges of the Jungle Owlet (distributed through South Asia) and Spotted Owlet (distributed through Iran, South and Southeast Asia). Another phylogenetically close species, Little Owl which is largely Palearctic in distribution, is hypothesized to have undergone severe range reduction during the Last Glacial Maximum, showing a postglacial expansion. The present study tests hypotheses on the possible role of Quaternary climatic fluctuations in shaping geographical ranges of owlets.

METHODS

We used primary field observations, open access data, and climatic niche modeling to construct climatic niches of four owlets for four periods, the Last Interglacial (120-140 Ka), Last Glacial Maximum (22 Ka), Mid-Holocene (~6 Ka), and Current (1960-1990). We performed climatic niche extent, breadth, and overlap analyses and tested if climatically suitable areas for owlets are nested in a relatively stable climate.

RESULTS

Climatically suitable areas for all owlets examined underwent cycles of expansion and reduction or a gradual expansion or reduction since the Last Interglacial. The Indian owlets show significant climatic niche overlap in the current period. Climatically suitable areas for Little Owl shifted southwards during the Last Glacial Maximum and expanded northwards in the postglaciation period. For each owlet, the modeled climatic niches were nested in climatically stable areas.

MAIN CONCLUSIONS

The study highlights the impact of Quaternary climate change in shaping the present distribution of owlets. This is relevant to the current scenario of climate change and global warming and can help inform conservation strategies, especially for the extremely range-restricted Forest Owlet.