Whilst birding the scrubby area at the side of Dhahran Waste Water Lake at the end of April I came across an Upcher’s Warbler busily feeding in the abundant vegetation that has been recently planted by Saudi Aramco. Even though I was on foot, as the bird was busy feeding I managed to get quite close and took the below photos, The species is an uncommon passage migrant through the Eastern Province that is rare in summer. The main identification points to separate Upcher’s Warbler and Eastern Olivceous Warbler are that Upcher’s Warbler is generally bigger and has a stockier appearance although this can be difficult to judge on a lone bird if unfamiliar with them. Wings, legs, tail and bill are all longer on Upcher’s Warbler than on Eastern Olivaceous Warbler with the legs and bill being thicker on Upcher’s Warbler. The tail on Upcher’s Warbler is long and ‘full’ and darkens towards the tip, which is not the case in Eastern Olivaceous Warbler. This darkening of the tail can be seen in the below photographs. The tail is also moved in a rather lazy swinging motion often sideways and also upwards and is also fanned, which is not often if ever shown by Eastern Olivaceous Warbler. The exaggerated tail movements of Upcher’s Warbler are often the first thing that draws attention to the species, especially if they are deep in cover.
