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  BIRDING AZORES

Untitled Document
  An odd group of geese on São Jorge.
 

2007-08-27: We have received a few responds to the occurrence of these geese. All have been concerning the odd Snow Goose looking bird, where the general meaning is that this is indeed a hybrid. We have also received some photos of similar hybrids thanks to Frédéric Jiguet, France, and from Andreas Uppstu, Finland. The main reasons for this bird being a hybrid are the too small and dark bill, the contrast between breast and flanks, and maybe to dark wing-coverts (lacking elongated white-fringed tertials). Also note that there is one more photo of this bird if you check the bird database.
   However - the main question is still unsolved. How do we classify this odd group of geese?

2007-05-09: In August 18th 2006 Dick Veenendaal saw and photographed a group of geese on Ilhéu do Topo at the eastern point of São Jorge. The photo, taken at a long distance, showed four geese of apparently three species. There was one Canada Goose Branta canadensis of one of the larger races, two Barnacle Geese Branta leucopsis, and one goose in size and colouration mostly resembling a dark (blue) phase of Snow Goose Anser caerulescens of the (lesser) nominate race.
   The composition of the group and the time of the year raised some questions like if the group had been placed there by humans, how long they have been there, and if they were undamaged and could fly. Ilhéu do Topo is a nature protected island, very difficult to access. But it has a very suitable plateau for foraging geese.
   Further investigations revealed nothing new, nobody seemed to be aware of the geese, and nobody could see any reason in why somebody would place them there, or if this even was possible.
   When I later on, in late January 2007, visited São Jorge, I was very surprised to find two of the geese still there on the 27th. They were even flying just a few meters disturbed by grazing sheep, and looked both fully winged. When I visited the area the day after, I could not find them there in spite of a long watch. They could possibly still have been there, since a small part of the little island is obscured from the watch point by the lighthouse at Ponta do Topo. Further checking with locals and João Monteiro, the Nature Warden for São Jorge, did not result in any more information.
   The two geese, one Barnacle and one Snow Goose of the blue phase, were photographed, but due to hard winds and long distance the quality became rather poor. Comparing the geese in the scope showed that there was a small size difference, where the Barnacle was smaller. The leg colour of the Snow Goose were typical more reddish-pink than yellow, but the bill showed maybe a little too much black in the reddish-pink colour. The flanks and belly of the Snow Goose showed a lighter dark colour than the darker breast, which is rather typical for the relatively common intermediate forms, but also something occurring in hybrid birds.
   So the occurrence is still something of a mystery. When did the group the first time set its feet on Ilhéu do Topo? Was it during some late autumn westerly storm in 2005, and did the group thereafter got stuck here and never left the area? Or does the group have a domestic origin, which one could suspect if the first occurrence was in late summer outside normal migration time. And the composition of the group is also rather odd, with two Barnacles, one Canada, and one Snow Goose - the latter maybe even a hybrid? This is if they all arrived together - which they of course not must have done.

 

Photo: Dick Veenendaal 2006-08-18

Photo: Staffan Rodebrand 2007-01-27

 

   There are very few wildfowl kept in the Azores apart from pure domestic ducks, and a few exotics like Spur-winged Goose and Muscovy Duck. The Terra Nostra Park in Furnas keep Wood and Mandarin Ducks, Black and Mute Swan, and a few more exotics, but normally the Azores is free of other wild species kept in captivity. Just single escapes of Mandarin Duck and Ruddy Shelduck are known so far, and almost all North American geese and ducks encountered here are considered of true and wild origin. Some are even verified by ring recoveries.
   So the question is open. How do we classify these birds?

Staffan Rodebrand, Sweden

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