Steppe Gull - barabensis

(last update: 8-9-2014 )

At breeding location.

Identification of Steppe and Caspian Gull.

eastern cachinnans adult, June 07 2011, Aktogay, East-Kazakhstan Province (46,57N 79,40E). Picture: Gabor Papp. These individual have slightly darker upperparts than most western birds, with more black on P10 and shorter pale tongue.	eastern cachinnans adult, June 07 2011, Aktogay, East-Kazakhstan Province (46,57N 79,40E). Picture: Gabor Papp. Subterminal black on P1-P10.
cachinnans-barabensis transition adult, July 20 2010, Turgay village (county Aqtobe), Kazakhstan. Picture: Ross Ahmed.	cachinnans-barabensis transition adult, July 20 2010, Sarykopa - Qostanay, Kazakhstan. Picture: Ross Ahmed.
barabensis adult, June 18 2010, Bagan, Novosibirskaya Oblast, Western Siberia, Russia. Picture: Tatiana Bulyonkova.	barabensis adult, July 13 2012, Karasuk, Novosibirskaya Oblast, Western Siberia, Russia. Picture: Sergey Pisarevskiy.
barabensis adult, July 13 2012, Karasuk, Novosibirskaya Oblast, Western Siberia, Russia. Picture: Sergey Pisarevskiy.	barabensis adult, July 13 2012, Karasuk, Novosibirskaya Oblast, Western Siberia, Russia. Picture: Sergey Pisarevskiy.

Knowledge gaps
4. Geographic variability and hybridisation in areas of overlap
There is discussion in the literature about the geographic variability of Caspian Gull (summarised in Malling Olsen & Larsson 2003) but little or no published quantitative data on the subject. So-called “eastern” Caspian Gulls reportedly have more black and less white in the wing-tip than western birds and so potentially complicate interpretation of the wing-tip trait scores presented here. The relatively invariant P10 pattern found in our Caspian sample (less black than white on P10) refers to western, ponticus-type birds. Despite statements in the literature, Caspian Gulls observed by us farther east on the breeding grounds have shown the same P10 pattern, with a whitish and deep tongue, pure white tip and less black than white, indicating stability of the basic characters of P10. During visits to southeast European Russia and southwest Siberia (May-June 2010), Caspian Gulls were found breeding in colonies along with birds phenotypically identical to “Steppe Gulls” Larus [cachinnans] barabensis; some intermediate individuals were also observed and photographed (GN unpubl. data). Presumed mixed colonies were reported from southern Siberia some years ago (Panov & Monzikov 2000). This evidence suggests that Steppe Gull is expanding its breeding range westwards and that hybridisation with Caspian is already taking place (Filchagov 1996). As a consequence of hybridisation, “eastern Caspian Gulls” with blacker wing-tips could in fact be yet another type of hybrid - between Caspian and Steppe Gulls. The influence of the latter is likely to be expressed, for example, in more black in the wing-tips of otherwise Caspian-like birds, as was observed in Siberia in 2010. Clearly, gull studies in SE Europe and western Asia are badly needed to resolve the complex relationships between these taxa.

Much of the evidence for hybridization between Caspian and Yellow-legged Gulls comes from Poland, where they now breed in a number of mixed colonies (Neubauer et al. 2006, 2009; Beran et al. 2010). However, the evidence from Poland is rather different from that from other areas of overlap (e.g. the Black Sea coast of Romania), where these species apparently do not hybridise (Klein & Buchheim 1997; Neubauer et al. 2010). There are other areas of potential overlap between these species, notably along the eastern and southeast shoreline of the Black Sea, and our understanding of the relations between Caspian and Yellow-legged Gulls would benefit from work there. The Black Sea is further interesting because the more easterly populations of Yellow-legged Gull found there appear to differ in a number of respects from western ones, including some traits that make them more similar to Caspian Gulls (e.g. more frequently a fully white tip to P10 and a longer tongue than on western birds). There remains scope for work describing quantitatively the plumage traits of eastern Yellow-legged Gulls so that the extent to which they overlap with those of other species or hybrids can be established.

5. Call and posture

Long call and long-call posture are important in the identification of Caspian Gull (details in Gibbins et al. 2010). However, there are no published data on the call or call posture of hybrids. Consequently, work is needed to determine what hybrids sound like and the posture they adopt when long-calling. Sonogram analysis, as used for example to assess the songs of Common Chiffchaff Phylloscopus collybita, Iberian Chiffchaff P. ibericus and suspected hybrids, would most likely prove insightful (Collinson & Melling 2008).

below: set of pictures of barabensis type, June 2007, Sverdlovsk oblast - SE Urals. All pictures by Annika Forsten & Antero Lindholm.

below: set of pictures of eastern cachinnans, June 2011, Aktogay, East-Kazakhstan Province. All pictures by Gabor Papp.