onsdag 3 augusti 2011

Shearwaters - Oceanic Sea Birds

Shearwaters are long-winged, elegant, and often very long-lived seabirds. In Norwegian waters, normally two different species of shearwaters may be encountered, the Manx Shearwater/Havlire (Puffinus puffinus) and the Sooty Shearwater/Grålire (Puffinus griseus).

The Manx Shearwater is currently, to my knowledge, holding the record for being the oldest known wild bird. Being ringed as an adult back in 1953, one bird that had/has its breeding area in Northern Ireland was caught again in 2003 at an age of 55 years. They nest in burrows in colonies especially around Great Britain and Ireland, but may be seen as far north as Norway. Outside the breeding season they live pelagic far out at sea.

The Sooty Shearwater is larger and darker than the Manx Shearwater. Most shearwaters are long-distance migrants in the extreme, but none more so than the Sooty Shearwater. Having their breeding areas in Antarctic and sub-Antarctic areas, the Sooty Shearwaters migrate northwards during the Antarctic winter. Tracking data suggest that they migrate north along the North American side of the Atlantic and then back south again on the eastern side of the Atlantic. The birds that we may see in Norwegian waters (typically in September) are thus probably on their southward migration and approximately 14000 km from their breeding colonies on the Falkland Islands.

The shearwaters in the Pacific are even more extreme and recent tagging data shows that they may cover a distance of 65000 km during their annual migration - to be compared with the diameter of the Earth which is 40000 km. It has also been seen from tagging data that they may cover a distance of 1000 km/day when they travel in the nutrient-poor areas around the equator and that they are capable of diving down to a depth of 68 meters.

Both the Manx and the Sooty Shearwaters feed on fish, squid, cephalopods and crustaceans and often follow whales to catch fish disturbed by the feeding of the whales.

Typical view of a Sooty Shearwater


Sooty Shearwater together with a Killer Whale/Orca


Sooty Shearwater


Manx Shearwater on a stormy day


Manx Shearwater next to the blow of a Sperm Whale

Another oceanic seabird, that is closely related to the shearwaters, can be seen in great numbers off the Norwegian coast - the Northern Fulmar (Fulmarus glacialis). Just like the shearwaters, fulmars spend most of their lives far out at sea and may become very old. They feed mostly on fish, but do not say no to a free lunch, like fish offal from a fishing-boat, or as here - a dead Sperm Whale.


Northern Fulmar

Northern Fulmars feeding on the carcass of a dead Sperm Whale

3 kommentarer:

  1. WOW! Kult med lirene! Grattis! Lire og spekkhugger på samme bilde - nice :) Tøft bilde av den døde spermhvalen, håper den døde av naturlige årsaker.


  2. Intressant!
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  3. Wirklich krass, kann mich Espen nur anschliessen.
    Grüsse von Jan