Each species of animal needs certain combination of plants, fellow animals, climate and landscape features to survive and successfully breed its next generation. Such a unique combination of ecological features is termed as habitat. The habitats are confined in length and breadth due to presence of ecological barriers like rivers, mountains, etc. or change in vegetation or presences of human settlements forming a boundary beyond which wildlife survival becomes difficult.
Any species of wild animal requires usually more than one habitat area to fulfill its survival needs around the year. Such habitats are connected by means of corridors which animals use to maintain their movements in time of needs for various reasons like mating (to maintain genes diversity among the population), food (depending on flora and fauna distribution within each habitats), survival (during calamities like flood and forest fire), etc. Corridors are on land routes that animals uses to cross over or migrate between habitats.
Corridors are necessary to maintain a healthy population of animals in any part of world due to the shrinking size of habitats and limitations of habitats in providing shelter to animals, especially during a time of crisis like flooding of habitats due to swelling river system, forest fire or drought.
Kaziranga National Park is home to at least 35 mammalian species of which some 15 are in threatened list of IUCN Red List. Some of the prominent spices in Kaziranga national park are greater one-horned rhinoceros, wild asiatic water buffalo, eastern swamp deer (barasingha), Asian elephants, gaur (Indian bison), sambar (a kind of deer), Indian muntjac, wild boars, hog deer, royal Bengal tiger, leopards, jungle cats, fishing cats, leopard cats, hispid hare, Indian gray mongooses, small Indian mongooses, large Indian civets, small Indian civets, Bengal foxes, golden jackals, sloth bear, Chinese pangolins, Indian pangolins, hog badgers, Chinese ferret badgers, particoloured flying squirrel, Assamese macaques, capped and golden langur, hoolock gibbons, etc.
The national park is surrounded by mighty river Brahmaputra in its northern bounds. Most of the park’s area inhabited by the animals cited above lies within the Brahmaputra river floodplain. It basically means that during annual flooding of river Brahmaputra, rivers swells in width and submerges most of the land within park forcing animals like rhinos, elephants, hog deer, water buffalo, deer, etc. to cross over to surrounding foothills or higher ground of the adjacent Karbi Anglong in order to escape rising water levels though four animal corridors. The NH 37 passes through all four animal corridors in this park along with many villages.
The national park was established to help sustain and propagate the wild life population. It countered wild life loss due to hunting. In the last century, a major reason for loss of wildlife around the world was hunting. In recent years, death due to hunting was limited by constant vigil against poachers. In 2017, poachers killed 8 rhinos as per official records. In the same year, 31 rhinos lost their lives in the flood and park lost at least 361 animals of various species due to the same. This number rises to 401, if we consider animal deaths due to vehicles through the animal corridor. Here, we are talking about NH 37 or AH 01 that crisscrosses the 430 sq km park.
It should also be noted that the flooding of river Brahmaputra is an annual occurrence, sometime twice in a year as in 2017 and also with few exceptional years like in 2018 when there was no flooding.
In the current year, around 95% of park is under floodwater and so far, reports of 17 animal deaths have surfaced. As the floodwater recedes, the actual number may rise.
In earlier times, during rise in water level due to flood, animals naturally used to migrate to higher grounds in the hills of Karbi Anglong. However, now animals have to cross many local village settlements and a busy National Highway 37 (Asian Highway 01) to reach their destination. Wildlife do not prefer to encounter human settlements in general. The same reason may have hampered any early attempt of migration due to the onset of rising water levels by the animals, leading to mass movement where they can’t hold back anymore with high levels of water and river currents. In addition to this, we see reports of animal deaths due to vehicles over NH 37 each year.
The NH 37 is a vital land connection between lower and upper Assam. If the same highway is closed for any reason, a detoured route from Guwahati to Jorhat would mean a road distance of 391 km (via NH 29 and NH 27) instead of 305 km, which translates to an increase in travel time by 2 hours if you’re driving.
In case it’s desirable to keep the NH 37 operational along with a way out for animals to move freely through the highway, the good news is that, some innovative solutions may still work.
In 2010, ARC international Wildlife Crossing Infrastructure Design Competition shortlisted 5 finalists with designs to meet similar challenges in issues of road transport safety, structural engineering, wildlife conservation and landscape ecology.
They have accepted designs in which animal corridors are maintained over wider green land bridges with plants and vegetation similar to the one existing within animal’s habitats over the highways. Such land bridges should be placed at meeting points of animal corridors and roadways.
In such cases, there would be fewer chances of animals encountering highway traffic and thus encouraging the wildlife in keeping up with its need for inter-movements between isolated adjacent habitats through their original corridors routes. Inspiration may be drawn from similar projects, which have worked in various parts of world to meet unique challenges faced by the wildlife of Kaziranga National Park.