Camera trap database of Tiger from Rajaji National Park, Uttarakhand

Study Extent

This study was conducted in Chilla range (148 km2) of RNP (820 km2) along the eastern bank of the river Ganges, which forms the western limit of THB II (~3000 km2; Johnsingh et al. 2004). Narrowly connected to THB I (~1800 km2) through the Chilla-Motichur corridor (Johnsingh et al. 1990), Chilla also maintains connectivity with Corbett Tiger Reserve (CTR) through the Rajaji-Corbett corridor (Johnsingh and Negi 2003, Johnsingh et al. 2004). The range is characterised by rugged hills ranging from 400m to 1000m in altitude with steep southern slopes and is drained by rivers and streams running north to south, most of which remain dry in late winter and summer. Broadly, the forests of this region can be categorized as Northern Indian Moist Deciduous Forest and Northern Tropical Dry Deciduous Forest (Champion and Seth 1968), with the major associations being miscellaneous forests on the southern slopes and Sal (Shorea robusta) mixed and Sal dominated forests on the northern slopes, while the valleys have extensive grasslands.

Sampling

Thirty camera-trapping stations were maintained through the study period in the Chilla range of RNP (Harihar 2005). These trapping stations were selected so as to maximise the capture probabilities of tigers (Karanth 1995). In order to systematically sample the area, sampling blocks (spatially separated) were identified within the intensive study area and the cameras were deployed in a phased manner. Sampling along the east of Ganges (Chilla and parts of Gohri ranges) was carried out during winter of each survey year in 4 blocks and on the west of the Ganges (Dholkhand West and Dholkhand East ranges) in 2 blocks during summer of each years. Each block consisted of 10 trap sites run for 15 consecutive days/occasions. Thus, each sampling occasion combined captures from 1 day drawn from each block. One trap-night was a 14-hour period (1700-0700 hrs) during which a camera was functional. All the 10 trapping sites in a block was checked on a daily basis. All photographs were then downloaded at the trap site using a laptop. Every tiger captured was given a unique identification number (e.g., RT-002) after examining the stripe pattern on the flanks, limbs and forequarters (Schaller 1967, McDougal 1977, Karanth 1995).

Method steps

1. All the images from individual camera-trap location were downloaded from the SD cards of cameras using a laptop and stored in different folders respectively. Individual tigers were identified on the basis of their stripe pattern on the flanks, limbs and forequarters and given a unique identification number. Within the same folder bearing the name of the camera trap ID/code, two subfolders were created to store images from each of the paired camera traps which enabled easy Geo-tagging. Geotagging images (Photograph) - It is the process of embedding geographical information i.e. latitude and longitude co-ordinates into the EXIF file (metadata) of an image, done with the help of Geosetter software. Once geotagged, an image can be visualized on a GIS platform/mapping software. Extracting image metadata- For images captured using digital camera traps, date, time, ISO setting, exposure mode, flash usage, focal length and geographic coordinates (geotagged images) extracted using freeware program such as BR's EXIFextractor. Assigning unique Identifiers to images: After the identification of individual tigers the data is organised in Modified Audubon core template where a unique identifier number is assigned to the images. A 22-letter alphanumeric string proposed as unique identifiers for camera trap images.

The Rajaji National Park (RNP) of 820 km2 forms the north western population limit of tigers in India and is bisected into two (west; 600km2 and east; 220km2 RNP) by the river Ganges. Rajaji National Park has a small population of tigers (large carnivores) which needs large areas for ranging and adequate prey base of ungulate species. The park also supports a healthy assemblage of wild ungulates such as spotted deer, sambar, barking deer, nilgai, wild pig and goral. Besides tiger, the park supports a healthy population of leopard. Other carnivores present in the park are sloth bear, Asiatic black bear, hyena, jackal, jungle cat, leopard cat and rusty spotted cat.