29 October 2012

Southern Grey Shrike - Dhahran Hills

Whilst birding the ‘patch’ last week I found a Southern Grey Shrike Lanius meridionalis in the bushes at one end of the spray fields. This is a favoured spot for shrikes to rest and hunt from and I was able to get quite close using the car as a hide (blind). The Grey shrikes in the Eastern Province of Saudi Arabia are very confusing and there is often healthy debate between the birders of the region over what species, and subspecies, individual birds are. Based on morphological and ecological characteristics and geographical distributions, several authors have divided the Great Grey Shrike species into two subspecies groups, a northern and a southern one with most recent authors going a step further and treating these subspecies groups as two polytypic species; Great Grey Shrike Lanius excubitor and Southern Grey Shrike Lanius meridionalis. This is based on alleged sympatry between the northern and southern groups in two areas without any evidence of interbreeding, in combination with differences in morphology and ecology. Intergrades between two Southern Grey Shrike subspecies that occur in Saudi Arabia, aucheri (mainly eastern areas) and elegans (extreme west), have been reported from areas where they occur in close proximity, such as south-west Israel, eastern Egypt and north-east Sudan indicating the possibility of gene flow between them. These hybrids are likely in western Saudi Arabia as well as the range overlaps here. Mauryan Grey Shrike (Steppe Grey Shrike) pallidirostris occurs regularly in the region as a fairly common migrant and winter visitor, with peak migration in mid-March and September to October. This complicates matters with Southern Grey Shrikes further as interbreeding occurs freely between pallidirostris and the locally breeding Southern Grey Shrike subspecies aucheri with an intermediate population occurring in north-east Iran. These birds could quite easily occur in the Eastern Province of Saudi Arabia as well. As you can see from the above the picture is far from clear and some ringing data would be very valuable on these birds.