Sunday, April 14, 2013

Greenish Warbler


Description

     The Greenish Warbler (Phylloscopus trochiloides) are widespread leaf warblers throughout their breeding range in northeastern Europe and temperate to subtropical continentalAsia. This warbler is strongly migratory and winters in India. It is not uncommon as a spring or early autumn vagrant in Western Europe and is annually seen in Great Britain. InCentral Europe large numbers of vagrant birds are encountered in some years; some of these may stay to breed, as a handful of pairs does each year in Germany.Like all leaf warblers, it was formerly placed in the "Old World warbler" assemblage, but now belongs to the new leaf-warbler family Phylloscopidae.This is a typical leaf warbler in appearance, grayish-green above and off-white below. The single wing bar found in the southern and western populations distinguishes them from most similar species (except Arctic Warbler P. borealis). It is slightly smaller than that species and has a thinner bill, without a dark tip to the lower mandible


     A latitude-based analysis of wintering birds indicated that more northerly P. trochiloides are smaller, i.e. this species does not seem to follow Bergmann's ruleIts song is a high jerky trill, in some populations containing a sequence of down- and more rarely up slurred notes.It breeds in lowland deciduous or mixed forest; non-breeding birds in the warmer parts of its range may move to montane habitat in summer. Individuals from southeast of the Himalayas are for example quite often seen in Bhutan during the hot months, typically in humidBhutan Fir (Abies densa) forest up to about 3,800 meters ASL or more, but they do not breed there and return again to the adjacentsubtropical lowlands in winter.The nest is on the ground in low shrub. Like its relatives, this small passerine is insectivorous.


Behavior, feeding and habitat

     It has a number of subspecies, of which P. t . viridianus is the most familiar in Europe. As it seems, it is a ring species, with populations diverging east- and westwards of theTibetan Plateau, later meeting on the northern side. Their relationships are therefore fairly confusing:

  • Eastern group: Greenish Warblers
    • Phylloscopus trochiloides trochiloides: Greenish Warbler
      • Southern rim of the Himalaya eastwards from Nepal into W China.
      • Dusky greyish green above, often traces of second wing bar.
    • Phylloscopus trochiloides obscuratus: Dull-green Warbler
      • Intermediate between trochiloides and plumbeitarsus.
      • Gansu and surroundings, China.
    • Phylloscopus trochiloides plumbeitarsus: Two-barred Warbler or Grey-legged Leaf Warbler
  • Western group: Green Warblers
    • Phylloscopus trochiloides viridanusWestern Greenish Warbler
      • Breeds Western Siberia to north-east Europe; at east of range south to NW India.
      • Dull green above, with yellowish supercilium, throat, breast and faint wing bar.
   

    The groups' origin lies probably in the Himalayan region, where trochiloides is found. This taxon is close to the parapatric obscuratus, and to plumbeitarsus which is geographically separated from obscuratus; they all can (and in the case of the former two do naturally) hybridizeP. t. plumbeitarsus is often split as distinct species, as it does not hybridize withviridianus in the narrow zone in the western Sayan Mountains where their ranges overlap. Song structure differs mainly between trochiloides and plumbeitarsus. The former has a fairly uniform, long, and warbling song.

    

   Around the Himalayas, song structure is similar, but songs are generally shorter. plumbeitarsus, on the other hand, has a long song that can be clearly divided into a warbling part, followed by series of up- and downslurred notes. The songs of obscuratus, and, interestingly, "ludlowi", are short, but contain the downslur elements too; in the latter, they uniquely appear at the start of the song.But phylogenetically, the western taxa are even more distinct. However, there is some gene flow between trochiloides and viridianus also, with their hybrids being especially common inBaltistan; they were once considered another subspecies ludlowi. The Green Warbler P. nitidus, now by many considered a distinct species, is a mountain isolate that diverged from ancestral viridianus.




     Amazing bird to watch, quite sharp and hyper-active one, found early morning around 7:15 am, clicked at the terrace, from the trees opposite to our house in Kulai, Mangalore. This time, this bird was not in much mood for hyper-activity, it was sitting silently making its routine "chirr"ing call from the tree. I am lucky to get this shot, whilst happily getting a shot before brushing my teeth in the morning. This beauty made my day a rocking one, as watching birds motivate me more than my music. Its very shy by its behaviour and it was difficult for me to get full frame images, as this was quite a little far, hence I have managed to get 1/4th cropped images of this spectacular bird. I was trying my new Canon EF 300mm F4L IS USM Lens, on my Canon EOS 7D, whereby I hadn't yet bought the 1.4 extender, which made this a little farther to my viewfinder.

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