lusitanius Yellow-legged Gull

(last update: 10-12-2013 )

Coordinators:
Gabriel Martín
Antonio Gutierrez
Rui Caratão
Mars Muusse

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lusitanius 1cy June
lusitanius 1cy July
lusitanius 1cy Aug
lusitanius 1cy Sept
lusitanius 1cy Oct
lusitanius 1cy Nov
lusitanius 1cy Dec

lusitanius 2cy Jan
lusitanius 2cy Feb
lusitanius 2cy March
lusitanius 2cy April
lusitanius 2cy May
lusitanius 2cy June
lusitanius 2cy July
lusitanius 2cy Aug
lusitanius 2cy Sept
lusitanius 2cy Oct
lusitanius 2cy Nov
lusitanius 2cy Dec

lusitanius 3cy Jan
lusitanius 3cy Feb
lusitanius 3cy March
lusitanius 3cy April
lusitanius 3cy May
lusitanius 3cy June
lusitanius 3cy July
lusitanius 3cy Aug
lusitanius 3cy Sept
lusitanius 3cy Oct
lusitanius 3cy Nov
lusitanius 3cy Dec

lusitanius 4cy Jan
lusitanius 4cy Feb
lusitanius 4cy March
lusitanius 4cy April
lusitanius 4cy May
lusitanius 4cy June
lusitanius 4cy July
lusitanius 4cy Aug
lusitanius 4cy Sept
lusitanius 4cy Oct
lusitanius 4cy Nov
lusitanius 4cy Dec

lusitanius adult Jan
lusitanius adult Feb
lusitanius adult March
lusitanius adult April
lusitanius adult May
lusitanius adult June
lusitanius adult July
lusitanius adult Aug
lusitanius adult Sept
lusitanius adult Oct
lusitanius adult Nov
lusitanius adult Dec

2cy: June

This 2cy June section shows a large group of Larus michahellis in active complete moult. All birds were photographed in the harbour or the near beaches of Peniche - Portugal, images made by Chris Gibbins.

The first images are two ringed birds: blue G:11C, which probably is from the Cadiz project. And another ring; orange 82RT or maybe another code (it is hard to determine from the image). This bird, which may be ringed by the Thames group, UK?

If this orange 82RT is a bird ringed in the UK, it nicely demonstrates that we cannot be sure all birds in this page are indeed local lustanius. This is always a question when unringed birds are involved. Of course, this bird was within the accepted range of this taxon in mid-summer when breeding was underway, but this is as much as we can say. As with all adult birds, it seems reasonable to believe adult birds of other taxa are in their breeding colonies as well, so adult birds around Peniche should most probably be local birds.

But there is a chance that some birds (especially immatures) are lingering 'winterers' or wandering from elsewhere and just finding a suitable location to finish the complete moult. Chris says: ".. Certainly the regular trips I have had here in Peniche indicate that many Lesser Black-backed Gulls linger through their first summer here at the beaches and harbours, and so michahellis from other populations could be doing the same..."

We know from ring readings that 2cy Lesser Black-backed Gulls from virtually all over West and North European colonies spend some early summer time at the beaches of Portugal, and it is reasonable to assume that michahellis is no different. Food resources are easily at hand and they just need a quiet place to moult.

The general idea about Mediterranean michahellis is: late summer they leave the breeding grounds and move NW to the Atlantic to feeding grounds. They are common from August onwards along the coast from N France into the Netherlands, rather soon after fledging. There must be a strong trigger to move NW for birds from off-Barcelona, S France and from Italian colonies, from which we see rings in the Netherlands, normally from late August onwards, with numbers building up quickly by September or October.

As a rule, michahellis then leave again (with graellsii?) and they are believed to follow a route along the Atlantic coast, which might bring them into Portugal. The rich feeding grounds (human spill-off in ports) make it an ideal place to linger for quite some time, including the energy-consuming moult period.

This leaves us with the following questions:
how many of the birds we show here on this webpage are Mediterranean michahellis and how many are local lusitanius? Is it possible to draw a line between phenotype characters in this group of birds?

We feel that, on average, Portuguese birds are smaller and slighter than Mediterranean birds, and less 'rangey'. In fact, their jizz is more like graellsii. Of course one can easily find some rangey birds on Portuguese beaches, but they are in the minority (and of course may be Mediterranean birds).

This topic nicely illustrates the need for more images in order to understand the variation of local lusitanius, and to construct a better framework with which to separate local birds from lingering Mediterranean michahellis."