Thursday, 3 July 2014

Great Skua

The Gt Skua or Bonxie (of Norse origin) has a fierce reputation for attacking other birds and people. This skua is wide spread over Shetland with the highest number on Foula and up on Hermaness- Unst.

My first encounter with a Bonxie was in NW Scotland close to Handa island where they breed. It passed close by giving excellent views. You could see the powerful body especially the neck which was thick. Move on a few years and we saw many on our first trip to Shetland and numerous since. Scotland has around 60% of the worlds population with the majority on Shetland.

This is a dark brown bird with streaking , sometimes golden brown, while the juvenile is warmer brown  un-streaked below. Its flight is very direct and powerful and is quick to move in on any bird or mammal. If you visit an area such as Hermaness then you will have to walk through many territories and therefore will be attacked. Birds will fly head on and do not deviate so your only response is to duck, i have spent many a minute discovering flowers this way.

Birds nest on moorland in colonies, producing two eggs and at this point become more aggressive. The older more mature birds nest higher on the moorland getting better views of intruders while younger breeding birds nest lower down. Birds lay two eggs, spotted olive brown in colour.

Bonxies have a habit of sitting away from the nest  on other mounds(the other adult bird) and often have three or four of these mounts within their territory. Birds don't breed until they are between 5-10 years old so perhaps we may see some decreases in future. They do live along time with a bird over 36 years old

After the have landed, birds have a typical display in which the raise their wings and lift their heads as well as calling.This is a typical stance after an attack.

Feeding is a big problem to most seabirds but for the Gt Skua it has managed to change its diet. Sand eels and fish discards formed a big part of the diet , both of which has declined. Therefore the Gt Skua has moved onto other prey items such as adult birds- Puffin, Guillemot etc , rabbits of which there are plenty in Shetland and eggs. In some years where food is scarce they even turn to cannibalism .

They even attack large birds such as gannets tugging on their wing and forcing them to crash into the sea and then stealing the fish. Even Gt Black Back Gulls are sometimes targeted but they don't have much success as these birds are just as aggressive.

This year birds seem scarce, with two farmers in the south mainland indicating that the numbers are down to 1/5 of what they were last year.

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