Quaternary climatic fluctuations and resulting climatically suitable areas for Eurasian owlets

Abstract

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 Athene blewitti is endemic to central India, and its range is encompassed within the ranges of the Jungle Owlet Glaucidium radiatum (distributed through South Asia) and Spotted Owlet Athene brama (distributed through Iran, South and Southeast Asia). Another phylogenetically close species, Little Owl Athene noctua, 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.

Contrasting Trends of Population Size Change for Two Eurasian Owlet Species—Athene brama and Glaucidium radiatum From South Asia Over the Late Quaternary

“…While the Jungle Owlet continues to expand into the MDH, the Spotted Owlet shows a declining trend after the LGM. The direction of these population trends is broadly consistent with predictions from the species distribution models from a previous study (Koparde et al, 2019), suggesting that their distinct niches had a significant impact on their population history. We note that we have sampled one individual of each species and our data may not be representative of trends across the range of these species.…”

“…The demographic reconstruction of population history of the two Owlet species appears to be broadly consistent with predictions from previously generated climatic niche models (Koparde et al, 2019) in terms of the direction of change. PSMC-based demographic inference coupled with Climatic niche models can be an effective means of understanding the population history of species (Kozma et al, 2018;Mays et al, 2018).…”

“…We expect the reverse trend for the Jungle Owlet, with contraction in N e during the glacial period and expansion toward the Holocene. However, a previous study using climatic niche models suggests that the extent of Jungle Owlet habitat was reduced (relative to the Spotted Owlet) during the LIG and gradually increased toward the MDH (Koparde et al, 2019). We use the PSMC-based reconstruction of past N e from whole-genome sequence data to investigate past population size dynamics of the Spotted Owlet and the Jungle Owlet over the late Quaternary.…”

Birds adapted to cold conditions show greater changes in range size related to past climatic oscillations than temperate birds

“…crex and A . noctua modeled, respectively, by 36 , 39 , 41 , result smaller than those proposed in this work. All the three different approaches used algorithms that risk overfitting (e.g., GAMs) or Maxent with a hard threshold selection of 10th percentile of presences (forcing range maps to be small), resulting in maps that underestimate the real behaviour of these species.…”

Playback-aided surveys and acoustic monitoring in the detection of the Endangered Forest OwletAthene blewitti

“…3" 2004) and b) Chelsea remotely sensed bio-climate data of average years 1981 to 2010 at a resolution of 30 arcsec (926 meters) (Karger et al 2021). We used the biovars function from the dismo package (Hijmans et al 2017) in R. We plotted the spatial changes of select bioclimatic variables across the presence-absence grids that are considered important for Forest Owlet detection, based on the niche models by Koparde et al (2019) (Supp. Figure S7).…”