Marmoras Warbler  across the border

One of the rarest vagrants I have seen in north-western Europe is a Marmora’s Warbler Sylvia sarda. It was Sunday 4 May 1997, while at the famous migration watchpoint near Breskens, when Magnus Robb and I heard about this bird. It had been discovered the previous afternoon by Vincent Legrand and Alain De Broyer at Knokke-Heist in Belgium (Legrand & De Smet 2002). We did not have to think long about driving the 27 km to the spot. Fortunately, it had stayed overnight and gave brief but proper views, while skulking through a dense vegetation of hawthorn and sea-buckthorn.

Marmora’s Warbler is like a slightly shorter-tailed and blue-grey version of Dartford Warbler S undata. The only colourful bits are the bare parts; the orbital ring is red, legs and eye are orange and bill base is pale pink to orange (on average, the bare parts are slightly more reddish than in Dartford). Juveniles, however, are more drab overall, with less conspicuously coloured bare parts. Marmora’s Warbler is found year-round on Corsica and Sardinia and at a few nearby locations and in winter in Algeria, Tunisia and Libya. All records in north-western Europe are from (late) spring.

Features separating first-summer and adult Marmora’s from the very similar Balearic Warbler S balearica – which has not yet been recorded in north-western Europe – relate mostly to structure, coloration and vocalisations. Marmora’s has a slightly sturdier body, stronger bill and shorter tail, while Balearic is structurally closer to Dartford. In Balearic, the underparts (particularly the throat) are noticeably paler than the upperparts and a faint pinkish or brownish wash is visible on the breast and flank. The bright and slightly more yellow-orange legs and bill base of adults in spring can also be striking. Furthermore, the contact calls are clearly different; Marmora’s sounds very much like European Stonechat Saxicola rubicola (trek… trek…), while Balearic’s equivalent is less rasping and has a nasal – House Sparrow Passer domesticus-like – quality (ch-rk… ch-rk…).

Vagrant Marmora’s have been known to sing; song phrases are usually fairly short (c 1.0-4.5 sec) and simple, built up of scratchy elements and clear trills, delivered at high speed. The pitch usually has an undulating or gradually descending character. Again, confusion with European Stonechat is a risk, although song phrases of that species are usually shorter and less hurried.

I admit that I have become a bit preoccupied with twitching – the term used for going after a previously located rare bird. It does not mean that I like watching common birds any less, but twitching a rarity every now and then certainly makes for some excitement. Like most twitchers, my activities are limited to a certain area; in my case the Netherlands. The only other rarities besides the Marmora’s Warbler I have ever twitched across the border, were a pair of Baillon’s Crakes Zapornia pusilla near Antwerpen in July 1999, a Bonaparte’s Gull Chroicocephalus philadelphia at Zeebrugge in January 2000 and a Black-browed Albatross Thalassarche melanophris on Helgoland in May 2015. My first Zitting Cisticola Cisticola juncidis and Iberian Chiffchaff Phylloscopus ibericus for the Netherlands were right at the border.

Ever since I started birding I have been keeping a list for the Netherlands. With every new species added, it becomes harder to get my list to an even higher number. After about 12 years, the number of new ones had dropped to somewhere between one and eight per year; my average for the last decade (2008-2017) is about four per year. Fortunately, life does not depend on these numbers. It is the versitility of birding that I love so much, not just the twitching. 


This looks like a nice place for the first Marmora’s Warbler for the Netherlands to turn up. Just a reminder: the birding hotspot of Skagen  Denmark’s northernmost town  already has two and both were found by the same birder...

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Published 23 March 2018