46 Indian Birds Vol. 5 No. 2 (Publ. 20th July 2009)

More news on the Acrocephalus warblers at Kanha Tiger Reserve

David Raju, S. Balachandran, Praveen J., C. R. Sarath & Mike Prince

Raju, D., Balanchandran, S., Praveen J., Sarath, C. R., & Prince, M. 2009. More news on Acrocephalus warblers at Kanha Tiger Reserve. Indian Birds 5 (2): XX–XX.

David Raju., Banjar Tolla, Taj Safaris, Manji tolla, Mukki-Baihar, Balaghat district, Madhya Pradesh, India. Email: davidraju@gmail.comS. Balachandran, Assistant Director Bombay Natural History Society, Hornbill House, Shaheed Bhagat Singh Marg, Mumbai, 400023, Maharashtra,

India. Email: bnhsbala@rediffmail.comPraveen J., 14/779(2), ‘Ambadi’, Kunnathurmedu P. O. Palakkad. Kerala. 678013, India. Email: paintedstork@gmail.com C. R. Sarath, Banjar Tolla, Taj Safaris, Manji tolla, Mukki-Baihar, Balaghat district, Madhya Pradesh, India. Email: kabiniman@yahoo.comMike Prince, Flat A, Ground Floor, Regency Alandon, Frazer Town, Bangalore 560005, Karnataka, India. Email: mike@bubo.orgMss received on: 5th June 2009.

Further to the note by Raju et al. (2008), on the sighting of a possible Large-billed Reed Warbler Acrocephalus orinus from Kanha Tiger Reserve (KTR) in April–May 2008, we were able

to trap the species in mist nets in April 2009. Here we present our findings, with morphometric data.

The warblers in question arrived in KTR, at the same spot they frequented in 2008, on 21st March 2009 (DR & SCR), and were frequently monitored by DR and his colleagues. The birds generally behaved as they had last year, including fanning their tails intermittently. Three birds were mist-netted on 4th April 2009 by SB of BNHS (Fig. 1), relevant biometrics obtained, photographs taken, and the birds ringed and released. SB, with his 28-year experience of handling several thousand Blyth’s Reed-Warbler Acrocephalus dumetorum and other Acrocephalus spp., in various parts of India, as part of the BNHS ringing programme, could not find any morphological characters that were distinctive in the trapped birds, from those of a Blyth’s Reed-Warbler. Table 1 summarises the biometrics of the captured birds along with the known biometrics of Large-billed A. orinus and Blyth’s Reed-Warbler. Three known Large-billed Reed-Warbler specimens

are labeled ‘Thailand’ (Round et al. 2007), ‘Type’ (Bensch & Pearson 2002) and ‘Tring’ (Pearson et al. 2008). Birds from KTR are identified by the last two digits of their BNHS ring (e.g., Z19457). Biometrics are also provided for Blyth’s Reed-Warbler, compared by Round et al. (2007), are labeled ‘PDR’, and Bensch & Pearson (2002), labeled ‘B&P’. Along with this, we also provide the measurements given in Svensson (1992), labeled ‘LS’, and Ali & Ripley (2001), labeled ‘SA & SDR’.

Based on the three known specimens of Large-billed Reed-Warbler, Pearson et al. (2008) provide the following in-hand criteria for distinguishing them from Blyths’ Reed Warbler.

A more rounded wing, with wing-point at 4th or 5th primary 1. and 5th primary emarginated.A larger bill (length to skull >19 mm; width at rear of nostril 2. >4.5 mm).A longer tail (>55 mm), and larger tail/wing ratio (>90%, 3. compared with <85% in Blyth’s Reed-Warbler).A slightly longer tarsus (>23 mm, but potentially 4. overlapping).A longer hind claw (>7 mm).5. Distinctly broad-tipped primaries and more point-tipped 6. rectrices.Acrocephalus warbler

Acrocephalus warbler—wing formula

47Indian Birds Vol. 5 No. 2 (Publ. 20th July 2009)

Phot

os b

y: S

. Bal

acha

ndra

n

Table 1: Biometrics of Large-billed A. orinus and Blyth’s Reed Warbler A. dumetorum, and the birds from Kanha Tiger Reserve(NA = Not Available, JU = Juvenile, AD = Adult. All measurements in mm)

Large-billed Reed Warbler Warbler from KTR Blyth’s Reed WarblerThailand Type Tring #57 #58 #59 PDR B&P LS SA & SDR

Min Max Min MaxWing 64 61 59 64.5 61.5 61 61.2 62.2 58 65 59 66Tail 60 57 55 57 54 56 51.9 51 NA NA NA NABill to skull 20.6 19.5 20 16.5 17 17 16.7 17.5 15.3 17.6 15 18Hind claw 7.5 7.2 7.3 5.5 5 5 5.2 5.2 NA NA NA NATail–wing ratio 0.94 0.93 0.93 0.88 0.88 0.92 0.82 0.82 0.74 0.86 NA NABill–wing ratio 0.32 0.32 0.34 0.26 0.28 0.28 0.28 0.28 NA NA NA NATarsus NA 23.5 24.5 21.5 21 21.5 NA 22.3 NA NA 21 23Bill to rear nostril NA 12.2 NA 12 11.5 11.5 NA 11 NA NA NA NABill width 4.8 4.6 4.7 NA NA NA 4.2 4.2 NA NA NA NAHallux NA 8.5 NA NA NA NA NA 7.1 NA NA NA NAOuter retrices to tail tip 6.7 9 NA NA NA NA 5.7 5.7 NA NA NA NAWeight NA NA NA 13 11.5 12 NA NA NA NA NA NAAge NA NA NA JU AD JU NA NA NA NA NA NA

Acrocephalus warbler—claw and undertail

The Kanha birds (Figs. 2 & 6) had emarginations on p3 and p4 (instead of p5) and the wing-point was at p4. Bill length, tarsus and hind claw measurements fell well within the range of Blyth’s Reed-Warbler. Primary tips and retrices did not match with the expected shape of Large-billed Reed-Warbler feathers (see Figs. 3 & 4 in Bensch & Pearson 2002). The only over-lapping feature was the longer tail (>55mm for two of the Kanha birds), and hence, a tail/wing ratio almost approaching that of a Large-billed Reed-Warbler (0.92 in one bird & 0.88 in the other two birds). It was perhaps the long tail coupled with the high tail/wing ratio that gave an impression of a short-winged Acrocephalus spp., in all the pictures made in 2008, leading Raju et al. (2008) to suspect that the birds could have been Large-billed Reed-Warblers.

SB conducted another mist-netting session at Point Calimere in southern India, where several Blyth’s Reed-Warblers have been caught in the past. Four birds were trapped on 22nd April 2009; none showed a wing formula or biometrics that matched those of a Large-billed Reed-Warbler.

Therefore it may be concluded that the Reed-Warblers recorded at KTR in 2008 and 2009 were not Large-billed Reed-Warblers. However, it is not clear why the tail lengths of all three specimens exceeded the known range for the Blyth’s Reed-Warbler. Acrocephalus warbler—tail feathers

Acrocephalus warbler—wing and tail

Assuming these were Blyth’s Reed-Warblers, does it mean that greater tail-wing ratios, and longer tails, are unreliable features for separating Large-billed Reed-Warblers from other Acrocephalus reed-warblers?

48 Indian Birds Vol. 5 No. 2 (Publ. 20th July 2009)

AcknowledgementsWe would like to gratefully acknowledge the help, support and encouragement we received, at every stage of this study, from Philip D Round, David Pearson, Peter Kennerley, and Staffan Bensch. Asad Rahmani helped in getting the required permission in time. Krys Kazmierczak has been a constant supporter for the study and helped put us in touch with relevant people. DR & CRS would like to thank their colleagues, Mahinder and Harsha, during the monitoring of birds. SB would like to thank his associates P. Sathiyaselvam, Junior Scientist, BNHS, Saraskumar Behera, and Manoj Sahani, Field Assistants, BNHS, who helped in trapping the species. We would like to acknowledge the timely response from H. S. Pabla, Principal Chief Conservator of Forests, Madhya Pradesh, by granting permission to mist-net the species. DR & PJ would like to thank Oriental Bird Club for providing a grant for studying this Acrocephalus warbler.

ReferencesAli, S. & Ripley, S. D. 2001. Handbook of the birds of India and Pakistan together

with those of Bangladesh, Nepal, Bhutan and Sri Lanka. Vol. 8 (Warblers to Redstarts). 2nd ed. Delhi: (Sponsored by Bombay Natural History Society.) Oxford University Press [Oxford India Paperbacks.].

Bensch, S. & Pearson, D. 2002. The Large-billed Reed Warbler Acrocephalus orinus revisited. Ibis 144: 259–267.

Pearson, D. J., Kennerley, P. R. & Bensch, S. 2008. A second museum specimen of Large-billed Reed Warbler Acrocephalus orinus. Bulletin of the British Ornithologists’ Club 128 (2): 136–138.

Raju, D., Praveen J. & Prince, M. 2009. A possible record of Large-billed Reed-Warbler Acrocephalus orinus from Kanha Tiger Reserve, central India. Indian Birds 4 (4): 130–132 (2008).

Round, P. D., Hansson, B., Pearson, D. J., Kennerley, P. R. & Bensch, S. 2007. Lost and found: the enigmatic Large-billed Reed Warbler Acrocephalus orinus rediscovered after 139 years. Journal of Avian Biology 38: 133–138.

Svensson, L. 1992. Identification guide to European passerines. Norfolk: British Trust for Ornithology.

Both photos: David Raju

Acrocephalus warbler—bill and faceAcrocephalus warbler—wing formula

Cattle Egret Bubulcus ibis preying on Indian Indian spiny-tailed lizard Uromastyx hardwickii in Kachchh

Kamlesh K. Maurya, I. P. Bopanna & Sutirtha DuttaMaurya, K. K., Bopanna, I. P., & Dutta, S. 2009. Cattle Egret Bubulcus ibis preying on Indian spiny-tailed lizard Uromastyx hardwickii

in Kachchh. Indian Birds 5 (2): XX–XX.Kamlesh K. Maurya, I. P. Bopanna & Sutirtha Dutta: Wildlife Institute of India, Post Box 18, Chandrabani, Dehradun 248001, India.

Email: kamlesh_amu@yahoo.co.inMss received on 28th November 2008.

We would like to report here an instance of Cattle Egret Bubulcus ibis preying on Indian spiny-tailed lizard Uromastyx hardwickii in Kachchh (Gujarat, India). These

observations were made in July–August 2006, during the egrets’ breeding season. After a span of two years there was heavy rainfall in Kachchh. By July Cattle Egret had attained their breeding plumage. The Cattle Egret is gregarious and associates closely with grazing animals. In the grasslands of Daun, more than ten herds of cattle have been observed per day, each herd comprising nearly 100–150 animals.

On 16th June 2006 at 0700 hrs, we reached the hide from where we were observing the behaviour of the Indian spiny-tailed lizard.

Subsequently we spotted a large herd of cattle at 0900 hrs, along with half a dozen Cattle Egrets that were associated with the herd. At this time, some of the lizards were basking while others had started foraging (Fig. 1), but after being disturbed by the cattle they scampered towards their burrows.

We followed the cattle to see the response of Indian spiny-tailed lizard, when we spotted a Cattle Egret hunting and feeding on Indian spiny-tailed lizard (Fig. 2).

We briefly describe how the Cattle Egrets hunted the lizards. An egret walked steadily towards a lizard, darted forward a short distance, and made a quick stab at it. If the prey was a hatchling or a juvenile, it was swallowed easily. If it was a larger individual, the egret jabbed at it for a few minutes and then started feeding.