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E-mail: [email protected] [PB] Shashank Dalvi, WCS-NCBS alumnus, F-21, NCBS, GKVK, Bellary Road, Bengaluru, Karnataka, India. E-mail: [email protected] [SD] Binanda Hatibaruah, Gottang Gaon, P.O. Limbuguri, Tinsukia, Assam, 786125, India. E-mail: [email protected] [BH] Manuscript received on 28 April 2018. Introduction In this note we present some insights on the identification, The flycatcher genusCyornis , a grouping of closely related ‘blue distribution, and status of these two puzzling taxa, from the result flycatchers’, is represented in north-eastern India by six species of field observations in recent years. (Kazmierczak 2000; Grimmett et al. 2011; Rasmussen & Anderton 2012; Praveen et al. 2018): Pale Blue- C. unicolour, Hill Methods Blue- C. banyumas, Large Blue- C. magnirostris, Blue-throated- We use a combination of authors’ field observations, re- C. rubeculoides, White-tailed- C. concretus, and Pale-chinned verification of selected private and public observations (trip Flycatchers C. poliogenys. Of these, the Hill Blue- and the Large reports, social media, eBird), and a tallying of known specimens Blue Flycatchers are superficially similar, and their status and to understand the current distribution and status of both the taxa. distribution in the region remains poorly understood due to their The re-verification effort specifically questioned an observer on apparent rarity, and difficulty in detection and identification, in the approximate location of the record, date, and whether the addition to inconsistent taxonomy (Stresemann 1925; Robinson species was confirmed by its vocalisation, or by plumage alone. & Kinnear 1928; Rasmussen & Anderton 2012; Wells 2007). The record was considered for our study only if its identification BARUAH ET AL.: Large Blue Flycatcher & Hill Blue Flycatcher 103 was confirmed based on its vocalisation, in addition to getting Table 1. Observed colour of tarsii and feet from confirmed photos of adult males good visuals (except one record of a Hill Blue Flycatcher from Colour of tarsii & feet Hill Blue Flycatcher (10) Large Blue Flycatcher (13) Nameri National Park, which had a detailed plumage description). Pale 2 7 Consequently, several public records of both taxa were not Pink 6 6 considered. Approximate altitudes of sightings were estimated Darkish 2 0 based on a description of their locations vis-à-vis known landmarks or mile-markers and observer’s estimate of distance differences of visible morphology are prohibitively difficult to and direction from those marks. Museum specimens were not confirm through optics, or even in high quality photos. Elevation examined; we relied on the findings of Renneret al. (2009). should be considered a suggestive factor in specific identification, We tested the reliability of plumage parameters listed in field rather than confirmatory. guides (Kazmierczak 2000; Grimmett et al. 2011; Rasmussen & Anderton 2012), attempting to positively differentiate both taxa in the field, as well as in photographs. Photographs were obtained Field identification & song from various sources, including our own, only for records that Morphological analysis (Renner et al. 2009) has shown that the were also verified by sound. The authors recorded all Large Blue- Hill Blue Flycatcher of the sub-species C. b. whitei, which is the and most Hill Blue Flycatcher sounds, used for this work, during form found in north-eastern India, is significantly different from field visits (a few Hill Blue Flycatcher sounds are extralimital, the Large Blue Flycatcher. But superficially they look similar to and their identification was re-verified). These were made using each other and, the authors conclude that they cannot always be portable directional sound recorders and then analysed using reliably identified by discerning plumage and structure through ‘Audacity’, an open source audio editor. Field visits in the eastern optics or photographs. Himalayas, during which these taxa were specifically investigated, Of the characteristics that are visible, through field optics, a occurred in the previous eight years. Large Blue Flycatcher has a longer and wider bill, by an average of 20% on both factors, and longer primary projection, longer by Results average 38% (Renner et al. 2009). It also has longer primaries and a shorter tail, but these are not apparent in the field and The Hill Blue Flycatcher, hitherto considered a winter visitor, might be useful pointers when the bird is in hand. We found was found to be a year-round resident in parts of the region. that the differences in bill width and length are very difficult, if It remains rare across its range throughout the year but its not impossible, to discern through optics in field conditions, and presence is detected more frequently in April–May, than in also in photos. The difference in primary projection is discernible winter. On the other hand, we did not find any wintering records in the field, or from photos, only at suitable angles.