Use of Tracking Strips and Automatic Cameras for Detecting Critically Endangered Jerdon’S Coursers Rhinoptilus Bitorquatus in Scrub Jungle in Andhra Pradesh, India
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Oryx Vol 36 No 2 April 2002 Use of tracking strips and automatic cameras for detecting Critically Endangered Jerdon’s coursers Rhinoptilus bitorquatus in scrub jungle in Andhra Pradesh, India Panchapakesan Jeganathan, Rhys E. Green, Christopher G. R. Bowden, Ken Norris, Debbie Pain and Asad Rahmani Abstract Jerdon’s courser Rhinoptilus bitorquatus is a Jerdon’s courser has not yet been detected. The use of nocturnal cursorial bird that is now only known from a tracking strips carries a small risk of misidentification of small area of scrub jungle in Andhra Pradesh, India. Its footprints of other species, especially yellow-wattled lap- population size, distribution and habitat requirements wing Vanellus malarbaricus, as those of Jerdon’s courser, are poorly known because of its elusive habits. We but has the advantage that large areas can be surveyed conducted a trial of a survey method that involved without the use of expensive equipment or night-time deploying an array of 5 m long tracking strips consisting fieldwork. We recommend the use of automatic camera of smoothed fine soil, and checking them for footprints traps to obtain confirmation of records of probable at regular intervals. We developed diagnostic methods Jerdon’s courser footprints. for distinguishing the footprints of Jerdon’s courser from those of other species. Tracks of Jerdon’s courser were Keywords Andhra Pradesh, automatic camera traps, obtained on about one strip-night in 30 from areas where footprints, India, Jerdon’s courser, Rhinoptilus bitorquatus, the species was known to be present. We suggest a pro- tracking strips. cedure for using tracking strips to survey areas where sparse (BirdLife International, 2001). A systematic survey Introduction of the species’ distribution would facilitate the assess- Jerdon’s courser Rhinoptilus bitorquatus (Charadriiformes: ment of its conservation needs, but Jerdon’s courser Glareolidae) is a small cursorial bird that had not been is diBcult to find because it is nocturnal, its calls are recorded for more than 80 years until its rediscovery in not known, and the wooded nature of its habitat and 1986 (Bhushan, 1986). Since then it has only been seen its retiring habits makes visual searches in daylight in a few restricted areas of scrub jungle in Andhra unproductive. Recent records of Jerdon’s coursers have Pradesh, India (BirdLife International, 2001). In the 19th mainly been obtained visually during night-time walks in Century the species was also recorded in the Godaveri lightly wooded scrub jungle, during which the observer valley, 600 km away, and may still occur there and in scans the ground with a torch whilst masking footfalls similar habitat elsewhere (BirdLife International, 2001). with an electrical buzzer (Bushan, 1986). On average, Jerdon’s courser is categorized as Critically Endangered Jerdon’s coursers are only detected once in several hours on the IUCN Red List (Hilton-Taylor, 2000) because it of searching, limiting the usefulness of this method. is believed to have a small and declining population, In addition, the eBciency of night-time searching is but information on its distribution and population is unknown, making the interpretation of negative results problematical. The assessment of habitat preferences Panchapakesan Jeganathan and Asad Rahmani Bombay Natural History by such surveys may also be unreliable because the Society, Hornbill House, Dr Salim Ali Chowk, Shaheed Bhagat Singh Road, method’s eBcacy seems likely to vary with habitat Mumbai 400 023, India. characteristics, such as the density of bushes and the Rhys E. Green (Corresponding author) Royal Society for the Protection of nature of ground vegetation. Birds and Conservation Biology Group, Department of Zoology, Downing In this paper we propose that tracking strips, which Street, Cambridge, CB2 3EJ, UK. E-mail: [email protected] retain imprints of the feet of animals that walk over Christopher G.R. Bowden and Debbie Pain Royal Society for the them, should be used in surveys of the distribution of Protection of Birds, The Lodge, Sandy, Bedfordshire, SG19 2DL, UK. Jerdon’s courser, with species identity being confirmed Ken Norris School of Animal & Microbial Sciences, University of Reading, by night-time searches or automatic cameras in areas Whiteknights, PO Box 228, Reading, RG6 6AJ, UK. where tracking indicates that the species is present. Received 30 July 2001. Revision requested 17 January 2002. The technique also has potential for surveying and Accepted 24 January 2002. quantifying habitat use of other ground-living birds that 182 © 2002 FFI, Oryx, 36(2), 182–188 DOI: 10.1017/S003060530200025X Printed in the United Kingdom Downloaded from https://www.cambridge.org/core. IP address: 170.106.40.219, on 28 Sep 2021 at 18:08:34, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S003060530200025X Detection of Jerdon’s coursers 183 are diBcult to survey. Tracking methods have often no rain. Tracks of birds were recorded, and photographs been used in surveys of mammals, but have rarely been taken from directly above and/or plaster of Paris casts applied to birds (Sutherland, 1996). were taken of samples of those tracks that were close to the size expected for Jerdon’s courser. Each visit to a strip on which tracks were recorded is termed a tracking Study area event, regardless of the number of footprints or their The study was conducted in scrub jungle in the Sri distribution on the strip. Occasionally it was noted that Lankamaleswara Wildlife Sanctuary, near Reddipalle, footprints had been obscured by strong wind, rainfall Cuddapah District, Andhra Pradesh, India (14°N79°E). or disturbance by humans or livestock, and the period Automatic cameras and tracking strips were placed in between such a visit and the previous one was therefore two areas of open scrub, surrounded by denser shrubs excluded from further analysis. After each visit, the and trees, where Jerdon’s coursers had previously been surface of a strip was smoothed. seen by P.J., A.R. and K.N. The two patches, JC1 and In addition to collecting plaster casts and photographs JC2, were 1.5 ha and 2.0 ha respectively and were 80 m of footprints from the tracking strips deployed in JC1 apart at their nearest. Tracking strips were also placed and JC2, we also did so from strips at other sites, in selected open areas of pasture and crop land outside including pasture and crop land near the reserve. These the reserve where other bird species were observed, so sites were selected because they were frequented by that their footprints could be obtained for comparison species whose footprints may be confused with those with those of Jerdon’s courser. of Jerdon’s courser and could be watched during day- time. We were thus able to obtain footprints that were known to have been made by particular species. We Methods also used automatic cameras to identify the species leaving footprints at some of these sites. Tracking strips Footprints were measured on plaster casts and on Fine loess soil was collected near the reserve and photographs. Straight lines running along the central passed through a 1 mm sieve. Particle size analysis of a long axis of the imprints of each of the three toes were sample of the sieved soil, using a Mastersizer (Malvern marked on the cast or photograph and the distances Instruments Ltd, Malvern, UK), showed that 50% of its between the intersection of these lines at the hind margin volume was composed of particles <27 mm in diameter. of the foot (B) and points at the tips of the outer (O), Soil and sand with larger particles did not retain clear central (C) and inner (I) toes were measured with vernier imprints, especially when dry. A strip of ground 5 m callipers to give distances BO, BC, BI respectively. For long and 25 cm wide was cleared of stones and its photographs the distances were calibrated by measuring sparse covering of dried-out grasses. The sieved soil a scale marked in mm, that was included in the photo- was spread along the strip, flattened into a layer 1–2 cm graph. The intersection point B coincides approximately thick, slightly compacted and then smoothed with a with the hind margin of the foot. Using the intersection builder’s trowel. A thin layer of soil, collected adjacent rather than the hind margin itself allowed the measure- to the strip, was dusted onto the surface with a sieve ment of footprints of running birds, which often do not so that any tendency for birds to be deterred from leave a full imprint of the hind part of the foot. The walking on it by its smooth surface or slight diCerence distances between the tips of the outer and central (OC) in colour from the adjacent soil would be reduced. Each and inner and central (IC) toes were also measured. The strip required c. 25 kg of soil. Ten tracking strips were angle between the long axes of the outer and central deployed in JC1 and eight in JC2 between 30 January toes was then calculated as arcos((BC2+BO2−OC2)/ and 7 March 2001. A distance of 24–72 m was main- (2*BC*BO)) and the equivalent angle for the inner and tained between each strip and its nearest neighbour, central toes as arcos((BC2+BI2−IC2)/(2*BC*BI)). The and positions were recorded using a Global Positioning angle between the outer and inner toes was the sum of System (Garmin GPS III). these two angles. Where we had measurements of more than one footprint from a given tracking event, we took means of these measurements for use in further analyses.