A Mystery Shrike
Yesterday, Gabriel and I paid a visit to Lac Tanma – our first of the season and of what will hopefully be a series of regular visits there.
We’d barely arrived near the lake, after a couple of failed attempts to find a driveable track towards the lake (too muddy!), when we noticed a shrike sitting on top of a thorny bush. The overall appearance was that of a fairly large, greyish shrike, but quite a few things were just wrong for a Southern Grey Shrike (which given the time of the year would have been surprising to see here, as it typically shows up between December and February/March).
Suspecting a hybrid, we took a number of pictures before the bird flew off, which allowed us to compare with photographs and descriptions of known hybrids. I vaguely remembered that a few years back (it turns out this was in 2010) a similar hybrid had been reported from the French Jura, and that there was a drawing of another French bird in the excellent Shrikes – A Guide to the Shrikes of the World (Lefranc & Worfolk 1997).
This is what our bird looked like:
In typical shrike fashion, this bird had a distinctive black “Zorro mask” with an otherwise grey head and largely grey back (faintly mottled brown); white scapulars; black wings with a fairly large, elongated off-white patch at the base of the primaries; entirely pale salmon-pink underparts (from the throat all the way to the vent); and a white rump contrasting with its long black tail. In the field we noted some narrow pale borders to tertials, but these are not well visible in the pictures.
While a lot of hybrids between two bird species typically resemble both parents in one way or another, showing intermediate characteristics, this is not the case here. Our bird superficially looks like a Southern Grey Shrike, but clearly isn’t one: the buffish underparts especially, but also the seemingly all-dark tail (no white outer rectrices) and the lack of distinct white markings on the tertials and secondaries. Moreover, the structure and size – even though our bird seemed quite large – were not right for Southern Grey which is larger and more powerful (cf. a couple of pictures taken last winter in Palmarin). The same pretty much applies to Lesser Grey Shrike, which in addition has a black mask that extends to the forehead and lacks the white scapulars.
So who are the parents? Based on comparisons with pictures of hybrid shrikes and with the drawing and description in Lefranc & Worfolk, these types of birds are considered to be hybrid Woodchat x Red-backed Shrikes. The former is the most common Palearctic shrike species in Senegal, while the latter doesn’t usually occur in West Africa. The black mask, grey head, and “pinkish-white” underparts are typical of Red-backed, while the white scapulars, rump and wing patch are indicative of Woodchat. The grey back is a bit odd but has also been observed on other presumed hybrids with these two species as parents, and the faint brownish mottling hints at a hybrid origin. Another option would be a hybrid Woodchat x Lesser Grey Shrike, though there’s apparently only one such suspected bird that has been observed, in Hungary in 1979 (Handbook of Avian Hybrids of the World, McCarthy 2006). Much less likely, and one would expect at the minimum a black front on such hybrids¹.
Now compare our bird with the painting of a hybrid noted in France in 1995, fig. 26g:
Comments on the identification of this bird are more than welcome of course!
As far as I know, this is the first record of such a hybrid in (West) Africa; all other published data are from birds on migration or on breeding grounds in Europe. In recent years there’s been one such bird in Switzerland (April 2014), one in the French Lot department (May 2014), while hybrid males have bred (successfully!) with female Red-backed Shrikes in 2005 in South-East Belgium (short note available in PDF here), and in 2010 and 2011 in France. Pictures of the 2010 Jura bird can be found e.g. here and here. At least 12 mixed pairs have been found in France, but it seems that nothing is known on the whereabouts of these birds outside the breeding season: do they migrate to East Africa just like Red-backed Shrikes, or can they be found anywhere in Woodchat Shrike’s wintering grounds? Lefranc & Worfolk describe the latter as “a vast belt running across the African continent just south of the Sahara and largely north of the huge forest areas”. Our observation would suggest that they can show up anywhere in that area.
Other than our peculiar shrike, we had a pretty good morning out birding, with close to 100 species seen. Lac Tanma didn’t hold an awful lot of waders (a few hundred only, mostly Black-winged Stilts) but we did confirm breeding once again of Kittlitz’s Plover, while a female Knob-billed Duck also showed signs of breeding as it was seen flying around several times (and sometimes calling, which is associated with courtship behaviour). There were about 250 Greater Flamingos (and ca. 220 more at lac Mbaouane), several Gull-billed, Caspian, and White-winged Terns, but very few herons. A surprise find was that of three Spotted Thick-knees on the edge of the lake’s floodplain, quite close to the main road. Several Diederik, African and Jacobin Cuckoos were seen or heard, as were a few Broad-billed Rollers (another wet season visitor) and a single Purple (=Rufous-crowned) Roller. As usual, Mosque Swallows were hawking insects above the lake shore and the baobab forest; the latter also had a singing Hoopoe and several Woodland and Grey-headed Kingfishers. Besides the shrike, the only European songbirds that we spotted were two Melodious Warblers.
A Purple Heron at a small marsh near the village of Beer was my first of the season; we also found African Swamp-hen, Red-eyed Dove, and African Thrush here. Lac Mbaouane was visited only briefly and we just scanned the NW side of the lake, which had a few dozen Common Ringed Plovers and some Little Stints, while a few Blue-cheeked Bee-eaters were flying over and a Red-necked Falcon dashed over the lake as it was hunting.
(Regular readers will wonder what’s happening at Technopole. Well, I paid my first visit in three (!) weeks this morning, together with Theo. Water levels are rising with every shower, so conditions are getting less ideal for waders. Still a few hundred Ruffs, some Curlew Sandpipers, ca. 50 Sanderling and a few Little Stints, a handful of Black-tailed and a single Bar-tailed Godwit, Marsh, Green, Wood & Common Sandpipers, Greenshank, Redshank, a few migrating Whimbrels, etc. Also Shikra, a Hoopoe, and again a Broad-billed Roller to name but the most interesting records. The most unusual record this past week was actually one from Almadies: a Hadada Ibis flying over our house one morning! More on that one later, if I get the chance to write something up.)
¹ N. Lefranc mentioned that a mixed pair senator x minor was found in France last year. And that so far, no hybrid or mixed pairs senator x meridionalis have been recorded.