Difficult to find accommodation in Mumbai? The city’s wildlife also agrees

It’s not just humans struggling to find a place to live in the overcrowded city of Mumbai. A study reported that the financial capital’s growing urban and peri-urban sprawl is still rich in wildlife, but forces animals to stay within the city’s few green fringes. The study, published in the journal PLOS ONE, was funded by the City and Industrial Development Corporation of Maharashtra and was carried out with the necessary permissions from the Maharashtra State Forest Department.

“Much of the Mumbai Metropolitan Area (MMR) has been overlooked (for biodiversity studies), despite being home to rich and fascinating biodiversity. The region includes remnants of primary forests such as the Karnala Bird Sanctuary (KBS), the Prabalgad-Matheran-Malanggad Hill Range (PMMHR) and Manikgad – forest patches typical of the Western Ghats, ”said Mr Sameer. Bajaru, lead author of the article and researcher at the Bombay Natural History Society, Mumbai.

The main objective of the study was to examine the impact of changes in land use and land cover (induced by urbanization) on amphibians, reptiles, birds and mammals. The team recorded 213 species – 25 mammals, 135 birds, 16 amphibians and 36 reptiles – and the effect of urbanization on all species communities.

The city‘s growing human population, currently 26.6 million, occupies 603 km² and is expected to reach 44 million by 2052, doubling in size to 1050 km². These factors eat away at the city’s natural habitats, reducing its forest patches. Mangroves, Mumbai’s main defense against flooding, are also losing ground due to development activities.

Peri-urbanization or the transformation of rural areas into large urban areas is a prime example of how population expansion is affecting the forests of Mumbai. “As a result, landscapes, where agricultural land and forests coexist, are transformed or fragmented by urban-industrial landscapes. This has created complex mosaics of diverse land uses and land cover in all ecosystems, ”says Bajaru.

The team sampled approximately 1976 km2 of the MMR using satellite imagery to identify land use and land cover under three main types: forest (11%), degraded forest (29%) and human habitat ( 45%). The team classified the types into semi-evergreen, moist deciduous, mangrove, scrub, grassland, human settlements, and agriculture.

They then determined how each species had adapted to land use change, both individually and as part of a community with other species, observing various factors. For mammals, they used camera traps and visual surveys, also looking for circumstantial evidence such as droppings, pellets, pug marks, hoof marks, scratches, ponds, carcasses and remains of parts of the body. For birds, a bird watcher standing at fixed sampling points recorded all birds heard or seen within a radius of 50 m (known as the fixed radius count method). They marked the quadrats with ropes for amphibians and reptiles, manually knocking over leaf litter, branches, stones, and checking rock crevices, tree holes, cracks, and buttresses for them.

“We used an advanced and robust statistical model known as ‘multispecies occupancy modeling’ or MSOM to estimate the occurrence of different species and their response to land use and land cover change in the region. RMM, ”says Bajaru. MSOM is a recent approach to discover how several species interact and coexist in landscapes with different land uses.

Their findings showed that the species richness of mammals, birds, amphibians and reptiles peaked in wooded areas.

“96% of mammals, 85% of birds, 93.75% of amphibians and 69.43% of reptiles have shown that species occupancy decreases where human habitat coverage has increased. While in general, forest cover has had a positive effect on species occupancy, ”he explains.

These species rich forests are now confined to high altitude areas of MMR such as Matheran, Prabalgad, Malanggad, Manaikgad and Karnala. The team suggests that measures should be taken to minimize or stop habitat loss due to development activities in these areas.

(Top right) Indian Mouse Deer (Moschiola indica) & (bottom left) Bombay Night Frog (Nyctibatrachus humayuni) – two endemic species of the humid deciduous forests of the Karnala Bird Sanctuary, Mumbai.
(Images courtesy of: Sameer Bajaru)

However, the team noticed notable differences based on the species’ food preferences. For example, they found that herbivores and carnivores were found more in undisturbed forests. In comparison, omnivores and insectivores such as the black kite, blue rock pigeon, common myna, Indian heron, red-wattled lapwing, house crow, and house sparrow had drifted to areas inhabited by human and increased in these regions.

“These results were not surprising as these species are highly dependent on food produced in landscapes dominated by humans,” says Bajaru.

The team also verified how the developmental history of a particular site affected species occupancy. For example, the fort of Prabalgad and Matheran underwent major historical transformations due to the timber trade in pre-colonial and colonial times. However, they have been found to be less disturbed than other areas dominated by humans and therefore rich in species.

Previously, Matheran had humid deciduous to semi-evergreen forests, but was converted into a hill station in the 1850s. Due to conversion and timber extraction and forest fires, the entire area has grown. is transformed into open and dry deciduous and scrub forests.

Bajaru says their preliminary study has generated a variety of data, and there may still be more to discover, which can be done through long-term monitoring of the region. And also, by mobilizing citizen science projects (involving the participation and collection of data by local citizens interested in the documentation and preservation of biodiversity), the construction of nature interpretation centers to sensitize people to conserving local biodiversity will help.

But this will only be possible if the forest areas survive and thrive. For this, local participation is crucial, says Bajaru.

“Forestry staff and local people should be trained to develop native moist or semi-evergreen deciduous tree nurseries to restore degraded habitats. Private landowners around areas rich in species identified in this study should be encouraged to take conservation measures such as planting native trees grown in nurseries operated by forest staff and local people, ”adds Mr. Bajaru. .

Planting native trees can restore primary forests, thereby increasing species diversity. However, this is impossible if more land is lost for development activities such as the construction of roads, railways and buildings that involve the conversion of natural habitats to human-dominated habitats. Local policymakers, the Forestry Department and local governing bodies like the Mumbai Metropolitan Region Development Authority (MMRDA) and the City and Industrial Development Corporation (CIDCO) could initiate and fund conservation programs, the authors suggest.

This article has been passed to the researchers, whose work is covered, to ensure accuracy.

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