A conservation status survey of hornbills (Bucerotidae) in the Western Ghats, India

The Western Ghats biodiversity hotspot in India is threatened by habitat loss and fragmentation, which is likely to impact large-bodied, wide-ranging species with specialised requirements such as hornbills. In this survey along the Western Ghats, we surveyed for four hornbill species that occur here: Malabar Pied Hornbill Anthracoceros coronatus, and Indian Grey Hornbill Ocyceros birostris (endemic to South Asia), Malabar Grey Hornbill Ocyceros griseus (endemic to the Western Ghats), and the Great Hornbill Buceros bicornis. We visited 45 localities across five states: Maharashtra, Goa, Karnataka, Kerala, and Tamil Nadu. These included 26 wildlife sanctuaries, 5 national parks, 13 reserved forests, and one plantation landscape. Across sites, we walked 80 transect surveys totalling a length of 286.4 km. In all, 631 individual hornbills (412 detections) were recorded across 35 localities. The Malabar Grey Hornbill was most frequently detected, and widely-distributed, followed by the Great, and Malabar Pied hornbills. The Indian Grey Hornbill, more widespread across India, was seen in only two locations in this survey. Hornbill encounter was up to five times higher in moist, and wet forests as compared to dry forest types. Based on hornbill distribution and protected areas, five important hornbill conservation landscapes were identified in the Western Ghats (Amboli–Goa–Dandeli, Anamalai–Parambikulam–Vazhachal, Nilgiris– Wayanad, Someshwara–Sharavati–Mookambika, Neyyar–Peppara–KMTR, and Periyar) along with key reserved forests (Kottiyoor, New Amarambalam, Vazhachal, Nelliampathy, Goodarickal, Kulathupuzha– Palode). Hornbill densities were estimated in two of the above landscapes, and are provided as a baseline. We highlight some key considerations for hornbill research and conservation, and future needs. Introduction A large body of research has shown that the threats of habitat loss, and fragmentation severely impact large-bodied, wide-ranging species as well as species that have highly restricted geographic ranges or specialised requirements. Among birds, for instance, this makes wide-ranging species such as hornbills, and restricted-range species (endemics), more significant for conservation attention. The sensitivity of hornbills to hunting and habitat disturbance, and their specialised requirements for diverse old-growth forests for feeding and nesting have been amply demonstrated across Asia (see Poonswad & Kemp 1993; Kinnaird & O’Brien 2007—for recent syntheses), including India (Reddy 1988; Kannan 1994; Kannan & James 1997, 2006; Mudappa & Kannan 1997; Mudappa 2000; Datta 1998, 2001; Datta & Rawat 2003, 2004; Balasubramaniam et al. 2004). Even in the case of the more widespread Indian Grey Hornbill, a species of drier and more open habitats, sensitivity to habitat alteration leading to local extinctions have been reported in studies at the northern extremity of the Western Ghats—Purna/ Ratanmahal, Gujarat (Trivedi & Soni 2006). In central Indian forests, their sensitivity to habitat disturbance due to logging has also been reported (Mehta 1998). Of the 54 species of hornbills known from the world (Kemp 1993), nine occur within India, and four occur in the Western Ghats: the Malabar Pied Hornbill Anthracoceros coronatus, and Indian Grey Hornbill Ocyceros birostris (endemic to the Indian Subcontinent), Malabar Grey Hornbill Ocyceros griseus (endemic to the Western Ghats), and the endangered Great Hornbill Buceros bicornis. Apart from the two smaller Ocyceros spp. , all other hornbill spp. , are rare and threatened, and have been placed under Schedule I of the Indian Wildlife (Protection) Act, 19721. Past research on hornbills in India has addressed many aspects of their biology such as breeding, nest selection, and diet (Reddy 1988; Kannan 1994; Kannan & James 1997, 2006; Mudappa & Kannan 1997; Mudappa 2000, 2005; Datta 2001; Datta & Rawat 2003, 2004; Balasubramanian et al. 2004). Less information is available on distribution and abundance patterns of hornbills, particularly in the face of large scale landscape transformations and continuing fragmentation and disturbance (Datta 1998; O’Brien et al. 1998; Reddy et al. 1990; Raman & Mudappa 2003). A recent survey by Balasubramanian et al. (2004, 2007) recorded hornbill distribution in a number of sites in Kerala, Tamil Nadu, Karnataka, and Goa in the Western Ghats, as well as in parts of the Eastern Ghats. This survey found the Malabar Grey 1 All hornbills (Family: Bucerotidae) were earlier placed in Schedule I; however, the two smaller Ocyceros have been removed from the listing. In what is possibly an oversight, the Malabar Pied Hornbill Anthracoceros coronatus appears to have been omitted from the listing as currently (15 August 2008) evident on the website of the Ministry of Environment and Forests, Government of India (http://envfor.nic.in/legis/wildlife/wildlife1.html).