OSLO BIRDER: Caspo

Tuesday, 13 January 2015

Caspo

I’ve settled into a daily rhythm which strangely enough revolves around gulls. Today I also succeeded in seeing an interesting one with the Caspian Gull turning up at Langvannet again after it has become less predictable the last week. It was sitting waiting for bread when I arrived at 0935 and showed well during a couple of spells when the gulls sat on the ice but twice they were scared by Goshawks and then took quite a while before they returned. I had two adult male Goshawks together at one stage (one chasing the other) and last week there was a 2cy there so this is clearly a popular take-away for this raptor.

I managed to quite easily pick out the Caspian Gull in flight which raises the possibility of IDing one on a seawatch in the future.

Moving back into Oslo I failed to find any interesting gulls which I had hoped the recent storm “Nina” may have pushed up into the inner Oslofjord. Water had been pushed in though and the sea was a good 2 metres higher than normal. The Botanical Gardens were also devoid of interest with a single Hawfinch and a singing Goldfinch the highlights (the fact it was singing rather than the species).

First a video of the Caspian Gull where it calls a couple of times. Some say they can pick out this species just on call. I lack the experience to do that. Here it is giving a short call rather than the “long call” when they throw there head back but I definitely wouldn’t be able to pick one out just on this call.

1st winter (2cy) Caspian Gull

2nd winter (3cy) Herring Gull left and 1st winter (2cy) Caspian right. 1st winter Caspian Gulls differ from Herring Gulls of the same age in that they have already moulted a number of grey mantle feathers which can be seen on the back. A potential trap for the unwary though is a 2nd winter Herring Gull though as can be seen here which has also moulted a lot of grey mantle feathers and can be quite white on the head. Note the rounded tips to the feathers of the Herring Gull which is typical of older birds which have moulted their juvenile primaries but that the same feathers are pointed in the younger bird as they are still the juvenile primaries.