1 Aug 2014

Purple Swamphens – Sabkhat Al Fasl

We have two subspecies or at least colour types of Purple Swamphen Porphyrio porphyrio in Saudi Arabia, a grey-headed type from the eastern P. p. poliocephalus group possibly P. p. seistanicus and blue-headed birds that may be P. p. caspius, which is also often grey-headed, nominate or  just be a colour variant of the grey-headed birds?. The nominate subspecies probably does not occur this far east, at least naturally, as birds from Israel are assigned to madagascariensis African Swamphen with old records of caspius, but none recently, and if the nominate occurred in Arabia you would expect it to have occurred in Israel as well. BWP says nominate porphyryio group is restricted to countries bordering west Mediterranean, well away from Arabia, although there is always a chance some escapes of the nominate form have set up residence in the area? madagascariensis African Swamphen does not appear to occur in eastern Saudi Arabia (although see comments below from Qatar) as none of our blue headed birds have even the slightest amount of green in the wing or on the mantle and are resident and seen in all months. As caspius juveniles show green on the scapulars it may be difficult to assign non green mantled birds to African Swamphen. There is, however, at least one record of African Swamphen from Saudi Arabia with one from the Red Sea coast at KAUST in 2013 which is the area you would expect to see them as it closest to their known breeding range.

Due to the confusion in the types occurring in Saudi Arabia I asked Neil Morris form Qatar what the status was there. He mentioned that it is thought the Qatar population, first recorded in March 2004, arose from the feral population in UAE, with the resident Qatar birds being African (Green-backed) Swamphen Porphyrio madagascariensis. Currently there is only one core population of about 15 pairs at Abu Nahkla, as other breeding sites at Sailiyah and Al Khor Reed Bed have been destroyed. Abu Nahkla itself will be drained and developed in the very near future, hence Qatar might lose this species altogether. Neill found the first and only record of an unringed Grey-headed Purple Swamphen (as yet unassigned to any particular race), showing no obvious signs of a captive origin, feeding on the lawns of Al Corniche Park near the Sheraton Hotel from 5-23 September 2012. It was originally accepted onto the Qatar List in Category D, but has recently been upgraded to Category A given that records were emerging of birds passing through the Eastern Province of Saudi Arabia.

I also asked Mike Pope from Kuwait the same question and he replied that the opinion was the 'blue-headed' was the nominate and the 'grey-headed' the sub-species. Richard Bonser on a visit to Kuwait some years ago suggested the Grey-headed birds were P. p. seistanicus.

The subspecies that may occur as they are relatively close to the region are:
porphyrio - east & southern Spain, southern France and Sardinia to Morocco, Algeria and Tunisia.
madagascariensis - Egypt, sub-Saharan Africa and Madagascar.
caspius - Caspian Sea, northwest Iran and Turkey.
seistanicus - Iraq and southern Iran to Afghanistan, Pakistan and northwest India.
poliocephalus - India and Sri Lanka through Bangladesh, Andaman Islands, Nicobar Islands and northern Myanmar to south central China (Yunnan) and northern Thailand.

Birds are generally listed occurring to groups, the nominate porphyrio group (porphyrio) the madagascariensis (African Swamphen) group (madagascariensis) and the poliocephalus (Grey-headed Swamphen) group (caspius, seistanicus & poliocephalus). Members of the Grey-headed group seistanicus & caspius are characterized on the basis of differences in average size or subtle colour differences, so identifying these subspecies in the field will be difficult. To confuse matters more several studies have shown that size differences may be induced by environmental factors such as food during the nestling stage and therefore, size differences alone is insufficient evidence for the existence of taxa, suggesting there is insufficient basis for the recognition of seistanicus & caspius as valid taxa. Although it has been suggested that there are colour differences between seístanicus & poliocephalus no diagnostic characters are known with some authorities suggesting seistanicus & caspius are probably best regarded as synonyms of poliocephalus.


What seems clear to me is that the names that have been applied to the birds in the region may be misleading as many of the subspecies are very similar and without morphological data it will be difficult to sub-specifically identify them. Obvious African Swamphens should not pose a problem but the Grey-headed birds should probably be best left as birds of the poliocephalus (Grey-headed Swamphen) group and the blue-headed birds left unassigned as they may be blue-headed birds of one of the Grey-headed group or possibly nominate birds. If we can obtain more details on the birds seen in Arabia, then a point raised by Neil would be very interesting to study – “could we have a situation where  'Western' Blue-headed Purple Swamphen, ‘Eastern’ Grey-headed Purple Swamphen and African Green-backed Swamphen are three different species all occurring within the region?”.

2 comments:

  1. A very nice bird species, I like the colours and your excellent pictures.
    regards

    ReplyDelete