Back in the late 1960s on my first trip to Spain with no sites guides and precious little information, I missed out on a few species that’d be a ‘shoe-in’ today and struggled to find still more. One elusive bird we did see was Olivaceous Warbler. (Now, following being split from the eastern form the species is called “Western Olivaceous”or even “Isabelline Warbler, but for simplicity I’ll stick with the name by which I first knew it). Seeing the Olivaceous is something I still remember well and not just because it was a tick! We’d stopped just south of Seville at some wayside venta for a coffee when, weaving amongst the leaves of the eucalyptus above our table, we spotted a dagger billed, pale brown “hippo”. Coffees untouched, we sprinted back to our van for our bins and then executed a swift U-turn back to the table to confirm our suspicions – it was an Olivaceous Warbler. However, what remains so vivid in my mind wasn’t so much the bird as the puzzled and bemused looks we got from the other diners. I swear some backed away from us convinced that we were dangerously demented and afflicted, at best, with some form of St Vitus’ dance. Some may have even crossed themselves!
It was over 30 years before I managed to go back for a second look and, naturally, seeing Olivaceous again was a priority. Looking at trip reports, I was surprised to find the species only infrequently recorded and then, all too often, seen at just one site - Laguna de la Mejorada (aka “Lago de Diego Puerta”). Interestingly, this couldn’t have been too far from that original sighting so long before. But I was determined to find my ‘own’ birds rather than following the crowd. As a result I spent my first couple of visits carefully searching in the habitat as per the “Collins Bird Guide.” That is to say in “bushy country …. scrub forest in uncultivated areas …. moister strips along water-courses … and …. gardens and cultivations.” Unfortunately, there seem to be an awful lot of places like this in southern Spain and none them appeared to have Olivaceous Warbler! To be honest after a number of fruitless visits I cracked and visited the ‘honey-pot site’ where, of course, I quickly obtained excellent views of this subtle and understated warbler. It was here, though, that the penny began to drop although it took another visit for it to clang loud enough for me to take proper notice!
It was over 30 years before I managed to go back for a second look and, naturally, seeing Olivaceous again was a priority. Looking at trip reports, I was surprised to find the species only infrequently recorded and then, all too often, seen at just one site - Laguna de la Mejorada (aka “Lago de Diego Puerta”). Interestingly, this couldn’t have been too far from that original sighting so long before. But I was determined to find my ‘own’ birds rather than following the crowd. As a result I spent my first couple of visits carefully searching in the habitat as per the “Collins Bird Guide.” That is to say in “bushy country …. scrub forest in uncultivated areas …. moister strips along water-courses … and …. gardens and cultivations.” Unfortunately, there seem to be an awful lot of places like this in southern Spain and none them appeared to have Olivaceous Warbler! To be honest after a number of fruitless visits I cracked and visited the ‘honey-pot site’ where, of course, I quickly obtained excellent views of this subtle and understated warbler. It was here, though, that the penny began to drop although it took another visit for it to clang loud enough for me to take proper notice!
Laguna de la Cigarrera
My next encounter with this ‘uncommon’ species was, somewhat ironically, at the bottom of the hill from Alcala de los Gazules about 5 minutes drive from my house. I’d passed a small bridge over a small stream several times without stopping to look, but late one May I decided that it was time to investigate further. It was the tamarisks that had attracted my attention for it was in these feathery bushes at Mejorada that I’d seen the warblers previously. Within minutes of stopping I’d found my first ‘own’ Olivaceous Warbler – and, yes, it was in a tamarisk. Armed with the knowledge that, in this part of southern Spain at least, I should ignore “bushy country …. scrub forest in uncultivated areas … and …. gardens and cultivations” to concentrate on“…. moister strips along water-courses” with tamarisks I began to look elsewhere. With the penny now firmly dropped, I explored all the tamarisk clogged areas I could find. Suddenly from being elusive and scarce, Olivaceous Warbler became quite the opposite. Although the habitat is relatively limited in extent, within such habitats I’ve found the species quite common. The Rios Corbones and Guadaira (i.e. near Arahal & Marchena) seem particularly good as do the margins of most lagunas and embalses in the region. Laguna de la Cigarrera (north of Espera) is particularlyfavourite of mine. They also occur in the tamarisk scrub along the boardwalk at Laguna de Medina (despite not being mentioned as being possible there by site guides). My hunch that looking in tamarisks is the key to find this species is now enshrined in the latest edition of the “Collins Guide” albeit on the plate rather than in the text (“often found in tamarisk stands”). As it happens now I’ve started finding them more regularly, I have also discovered them in ‘bushy country etc’, but only when tamarisks are fairly close at hand.
Olivaceous Warbler distribution
Looking at my distribution map (taken from the latest Spanish Atlas) the many linear worm-like areas of occurrence clearly mark river valleys. Many of the larger blocks of land where it’s found are in broad lowland regions (e.g. Seville province) criss-crossed with channels and some isolated occurrences appear to coincide with lagunas/embalses. The map also demonstrates the key importance of Andalucia for this species with only scattered pockets elsewhere in Spain (other than in the Ebro valley). Originally the population was thought to be in the region of 1,000 pairs, but the latest estimate puts it over 5,000 which seems much nearer the mark to me.
Olivaceous (top) & Melodious Warbler (bottom)
In the context of the UK the identification of Olivaceous Warbler is distinctly tricky since it has the be distinguished from several other rare hippolais warblers (not to mention a couple of Acrocephalus warblers). However, in breeding habitat in southern Spain, the only realistic confusion species is Melodious Warbler (although Reed Warbler may sometimes cause momentary confusion). Structurally, Melodious and Olivaceous are similar although to my eyes Melodious has a thicker neck and more rounded head and so lacks the sinuous snake-like look of Olivaceous. Fortunately, plumage is a safer guide. Olivaceous is a drab sandy-brown above (with pale lores) and a similarly drab off-white below. In contrast, Melodious is more olive than brown above and the underparts (and lores) suffused with pale lemony-yellow. Although they never have the solid buttercup-yellow underparts that some older books show (which can colour expectations). My watercolor sketch shows (or is supposed to show!) a fairly typical Melodious, but caution is advisable since some birds can be paler. Note too, that stong light can drain the colour to make birds look paler and that, on a brief view, perceptions of colour may be inaccurate. However, with a good view the colour differences are constant and any bird that shows a lemony wash will prove to be a Melodious. Both have a similar song although, to me at least, Olivaceous always carries a whiff of Reed Warbler whereas Melodious tends to sound more like an aberrant Sylvia warbler (e.g. Sardinian Warbler).
So next time you’re in southern Spain in late May – and I recommend it – investigate any large stands of tamarisk you come across. Listen carefully for a not-quite-Reed-Warbler song and, with luck, you’ll see this elusive bird….. they’re not as rare as people think!
So next time you’re in southern Spain in late May – and I recommend it – investigate any large stands of tamarisk you come across. Listen carefully for a not-quite-Reed-Warbler song and, with luck, you’ll see this elusive bird….. they’re not as rare as people think!
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