The Western Ghats is one of four biodiversity hotspots of India. While the habitat may be biodiverse, it also faces a grave threat of destruction. A major criterion to select a biodiversity hotspot is the presence of endemic species, i.e. species that are confined to a limited area. The area can be a few square kilometres or a few hundred square kilometres. As far as birds are concerned, 26 species are endemic to the Western Ghats. The Nilgiri laughingthrush is one of the endemic species that is confined to a limited area in the Western Ghats that may not be more than a total of even 300 sq. km.
Laughingthrushes belong to a large family containing 135 species, but not all species are necessarily called “laughingthrush”: The scientific name for the family is Leiothrichidae and this diverse family has many species like minlas, babblers, cutias, barwings, and sibias which are considered its members. There are about 70 species with the moniker “laughingthrush” attached to their name, and Nilgiri laughingthrush is just one of them. It is also known as rufous-breasted laughingthrush or black-chinned laughingthrush.
In India, we have 30 species of laughingthrushes, mostly confined to the Northeast and the Western Ghats. The Nilgiri laughingthrush (Montecincla cachinnans, earlier called Strophocincla cachinnans) has perhaps the smallest distribution among its relatives. As the name indicates, it is found in the high reaches of the Nilgiris and adjoining hill ranges. Due to its limited distribution range and ongoing threats, IUCN has listed it as Endangered in the Red List.
Keeping up appearances
The Nilgiri laughingthrush is a small bird with a very pronounced white eye-stripe, and a conspicuous white supercilium or eyebrow. The upper parts are olive-brown, while breast and belly are bright rufous. The chin is black, which is where it gets its second name “black-chinned laughingthrush”. The male and the female look similar as there is no difference in plumage.
Resident of the shola forests
The Nilgiri laughingthrush is a bird confined to shola forests that are a characteristic feature of the southern Western Ghats. During the last 200 years, the shola forests have seen various threats such as clear felling to convert them in to tea gardens or plantations. Invasive plant species and overgrazing are other major threats.
It feeds on invertebrates and nectar, mostly within 3 metres off the ground in dense forests. It is a sedentary resident, inhabiting dense undergrowth and moist, shady lower story vegetation of evergreen and semi-evergreen forests, especially densely wooded ravines and forest edges, generally higher than 1,900 m. Occasionally, it may occur in thick gardens, patches of natural scrub, but is absent or uncommon in Eucalyptus, tea and Acacia plantations as it mostly prefers natural forests.
Nesting: A couple’s activity
The Nilgiri laughingthrush generally nests in the thick foliage of shola undergrowth near the edges. Both sexes participate in nest building, incubation, and care of young ones. The breeding pair defend its territory from other pairs of its species. Their nest is cup-shaped and comprises mainly green moss. Feathers, dead leaves, rootlets, threads and pieces of polythene, and fine grass blades are used for lining the nest. The nest is built between forks of branches, generally 2-3 metres from the ground. The nest rim is attached to the fork using moss.
Threats: Fragmented sholas, plantations and urbanisation
About 100 years ago, the Nilgiri laughtingthrush was probably a very common bird in the upper Nilgiris as the shola forests were extensive. However, now it is confined to fragmented sholas, amidst plantation, agriculture and urbanisation. Based on the habitat suitability assessment, one of my students, Dr Ashfaq Ahmad Zarri, studied this bird and found that total area occupied by it is no more than 268 sq km. This total area is in 584 highly fragmented patches (natural as well as man-made), distributed all over the Nilgiris. The smallest suitable patch identified by the model was 31.8 sq m and the largest patch was 7.5 sq km. Also, 80 per cent of all patches were smaller than 0.5 sq km. Our study shows that the Nilgiri laughingthrush has a much narrow area of occupancy than thought earlier. The total world population could be less than 2,000 individuals.
Many studies have proved that fragmentation increases the rate of nest predation and reduces breeding success. Most shola patches in the non-protected areas have been degraded and encroached. Structural changes of the shola may affect the breeding success by increasing the risk of egg and chick predation, resulting in local population decline. Predators around the nesting habitat of the Nilgiri laughingthrush include the jungle crow, house crow, crow-pheasant, dusky palm squirrel, brown palm civet, small Indian civet, common mongoose, and stripe-necked mongoose.
We also found a high percentage of nests with infertile eggs. The indiscriminate use of inorganic pesticides could be one of the reasons. Pesticide use is very common all over the Nilgiris, except in the Mukurthi National Park, which is just a small part of the overall distribution range of the Nilgiri laughingthrush. Despite a wealth of literature on the negative impacts of such chemicals on biodiversity in many areas, the kind and amount of inorganic pesticide usage in Nilgiris is largely unregulated, like in the rest of India.
Creating safe havens
Mukurthi National Park (78.46 sq km) is the only protected area in the Upper Nilgiris. The natural habitat of the Nilgiri laughingthrush in the rest of the Upper Nilgiris is practically unprotected and thus faces various threats. We recommend that the size of the Mukurthi National Park should be increased to include Avalanche, Upper Bhavani and Kundha forest ranges located to its east. This proposal is long standing for clearance by the authorities. We also identified many other sholas such as Naduvattam, Bison Swamp, Governor’s Shola, Cairn Hill Reserve Forest, Longwood Shola, and Taishola as important habitat of this globally Endangered bird. Secondly, organic farming in the Nilgiris should be encouraged and incentivised. If necessary, organic farming should be subsidised and crop insurance of inorganic farms should be removed. The Nilgiri laughingthrush uses the wattle plantation adjoining Shola as a corridor for movements between the shola patches. If it is not possible to restore the shola in such places, the plantations should be maintained so as to minimise the fragmentation of populations of this endangered bird.