A four-day bird survey found something at Siruvani that had never been recorded outside the Nilgiris

The Siruvani hills were, until quite recently, an ornithological blank. Neighbouring forests had been worked over for decades — Silent Valley to the north-west, the Walayar and Dhoni ridges to the south — but as the survey team put it, what was known about the birds of Siruvani had never been collated, and very little was published. That changed over four days in February 2007.

What the survey did

About 35 birdwatchers from across southern India worked from six base camps — Muthikulam, Karimala, Kuravampady, Singampara, Koodam and Pattiyar — chosen so that every representative habitat was covered. They walked 36 transects over the four days, morning and late afternoon, counting individuals as well as species, and held a plenary at the end where every doubtful record was thrown out. The result was published the following year as Praveen J. and P. O. Nameer, “Bird diversity of Siruvani and Muthikulam Hills, Western Ghats, Kerala”, in Indian Birds 3(6): 210–217.

The tally: 158 species, of which 14 are endemic to the Western Ghats, and nine are Red Data Book species. Kuravampady, where plantations meet natural forest, was the most diverse camp — the usual reward of an ecotone — while the high, cold camps at Muthikulam and Karimala recorded the fewest species and some of the most interesting ones.

The bird that should not have been there

The find was the Nilgiri Laughingthrush, an endangered bird whose entire known range was the Nilgiri Plateau. The Muthikulam team recorded 18 sightings totalling 33 individuals, from Muthikulam across to the Elival ridge, mostly above about 1,600 metres — the first record of the species outside the Nilgiri Plateau, and, the authors suggest, potentially the largest population of it in Kerala. Around five of those encounters, 13 birds, came from the southern ridge of Elival peak.

Beware the number, though. Summaries of this paper circulating online give the Siruvani population as “200–250 individuals”. The paper says 18 sightings of 33 individuals. We print the paper.

The same survey turned up the vulnerable Nilgiri Wood-Pigeon at nine encounters, vocal along the southern slopes of Elival; the vulnerable White-bellied Shortwing in thick Strobilanthes undergrowth at Muthikulam; a single vulnerable Broad-tailed Grassbird on marshy ground near the dam; and the near-threatened Tytler’s Leaf-Warbler in the sholas. Seven species were found breeding during the survey, including the Great Cormorant and Chestnut-headed Bee-eater at Siruvani dam itself.

Why here, of all places

The answer is a gap in a mountain range. The Palghat Gap is a roughly 40 km wide lowland break in the Western Ghats, and it is a real barrier: the high-altitude endemic life of the Nilgiris is cut off by it from the hills to the south. North of the Gap there are only a handful of compact high plateaus — Siruvani–Muthikulam among them — that reach the altitudes those species need. Siruvani’s forests run from about 500 m to 2,060 m at Elival peak, with rolling grassland and stunted shola above roughly 1,700 m at Muthikulam and Karimala. That grassland is why an assessment of these hills matters out of all proportion to their size.

It is recognised accordingly: the Muthikulam–Siruvani Reserve Forest is listed as an Important Bird and Biodiversity Area and as an Alliance for Zero Extinction site, and was confirmed as a Key Biodiversity Area at its last assessment in 2016. Its area is given differently by the two databases — 284.78 sq km (28,477.75 ha) on the KBA factsheet, 24,700 ha on the BirdLife IBA entry — and we print both rather than pick. The forest also holds Vateria macrocarpa, a critically endangered evergreen tree endemic to this region.