Even though climate change is seen as a major topic of discussion around the world, the impact of the environmental phenomenon is also becoming quite evident. ER Sreekumr and Dr PO Nameer, researchers at the University of Kerala’s Wildlife Department, recently conducted a study on the influence of climate change on two species of migratory birds.
The study was carried out on two species of flycatchers with restricted distribution and dependent on high altitudes: the black and orange flycatcher (BOF) Ficedula nigrorufa (Jerdon, 1839) and the Nilgiri flycatcher (NIF) Eumyias albicaudatus (Jerdon, 1840), to determine how they react to predicted climate change scenarios. The researchers used 194 and 300 independent points of occurrence for BOF and NIF to develop climate models and understand species responses to climate change scenarios using the MaxEnt algorithm.
The model predicted the current extent of occurrence of 6,532 km² suitable for FRO and 12,707 km² for NIF, within their range. However, only 27% and 24% of the existing suitable area of BOF and NIF, respectively, falls within the network of protected areas in the Western Ghats. Future forecasts suggest an appropriate area loss of 20-31% for BOF and 36-46% for NIF by 2050.
Climate change induced by human (anthropogenic) activities and increased environmental degradation have put millions of species in danger of extinction. According to a recent report by the Intergovernmental Panel on Climate Change (IPCC), anthropogenic activities will cause the global temperature to rise by 1.2 ° C between 2030 and 2052 above pre-industrial levels. Erratic environmental conditions, declining species abundance and widespread extinctions are some of the significant predicted effects of climate change, the study noted.
The oscillating climate and unique floral structure of mountain ecosystems provide species-specific microclimatic conditions and habitat, and these mountain ecosystems are known as “sky islands”. The Western Ghats (WG), considered one of the 36 biodiversity hotspots in the world, is located in southwest India and consists of such celestial islands. Palakkad Gap is the main discontinuity of the entire 1600 km section of the Western Ghats. Since 2012, the Western Ghats have also been a World Heritage Site13, and two ranges of hills in the region (the Nilgiri Hills and the Agasthyamalai Hills) have been recognized as Biosphere Reserves by the United Nations for education, science and culture (UNESCO), according to the study.
The Western Ghats mountain range is highly endemic with several species restricted to a narrow elevation range16. This specialized habitat is now deteriorating due to changing climatic conditions and human activities17–19. Under the looming threat of global warming and habitat loss from climate change, it is essential to assess the plight of the Westers Ghats habitat specialists, so that corrective conservation strategies can be planned, according to the report,
The Black and Orange Flycatcher and the Nilgiri Flycatcher are monotypic species endemic to the southern Western Ghats and confined to higher altitudes. BOF prefers the understory of shola forests, especially Strobilanthes and bamboo thickets, among patches of stunted evergreen forest on the heavenly islands of the Western Ghats and distributed above 700 m elevation, but more frequent near 1500 m and more. The NIF is also found above 600 m altitude but more frequently above 1200 m.
Degraded forests and timber, tea, coffee and cardamom plantations adjacent to forest areas are also considered suitable habitats. The NIF feeds mainly on invertebrates; however, it also consumes fruits and berries of Vaccinium spp., Syzygium spp., Cestrum spp., etc. to the current status of the Birds of India report.
It is essential to recognize the effect of climate change on endemic species due to their restricted distribution and specific habitat needs26.
Species distribution models (SDMs) are practical tools for understanding the relationship between species occurrence and environmental factors. SDMs also help determine previously unknown areas of a species based on the species’ known points of occurrence and predictor variables.
The study predicted suitable locations along high elevation regions for two species of restricted-range flycatchers in the Western Ghats. Of the two, the NIF has more widely distributed suitable areas available in the South West Ghats. BOF is restricted to high altitude pockets and its distribution is more isolated than NIF. Few occurrence data are available in the Brahmagiri Hills for the two species. In the case of NIF, the model predicts additional suitable areas in the BR Hills, but the species may not be found there due to unavailability of montane habitat. In addition, the NIF is not a long-distance migrant and these predicted suitable areas are within 50-100 km of the known range of the species. The regions of Agasthyamalai Hills, Pandalam Hills, Anamalai Hills, and Nilgiri Hills are the primary habitats for both species of flycatchers. BOF and NIF have a strong preference for mountain habitats, according to the report.
The results of the study were published in the latest edition of the leading scientific journal Current Science. The study was carried out as part of ER Sreekumar’s doctoral research.