Wednesday, October 14, 2009

My favorite birds--Sulidae edition

Hi all,

time for another installment of "my favorite birds" (this segment is also known by its alternative title "I am not enjoying my job that much").

Northern Gannets are gorgeous birds. The color balance of the cream body feathers, the rusty-orange crest, and the aquamarine eye ring creates a beautiful whole. They are long and graceful soaring fliers (they have a lot in common with albatross in that regard). they have always been a favorite bird of mine.

Northern Gannet's live in the north oceans and are part of the Genus Sula that includes Boobies and Gannets (including the famous Galapagos denizen the Blue-footed Booby). (I am not dignifying your Booby jokes). These birds share a common shape and physiology. They are "plunge divers" which means that they dive into the water from a substantial height and are able to make a move underwater to grab fish. This is a different strategy from the Alcids (e.g., Puffins) that can swim underwater for prolonged periods and from dippers/skimmers that do not reach as deep into the water column.

Northern Gannets nest together in colonies on remote rock outcroppings. This is for the simple reason that bird eggs are tasty, therefore, parent birds have to nest somewhere that land-based predators--fox, rats, snakes, bear--can't get them. This limits their nesting ground habitats to land without mammalian predators--at-sea outcroppings or very steep cliffs.

If you ever get a chance to visit a seabird colony (there is a gorgeous one in newfoundland) you should take it. It is a singular experience.

Stay tuned for eventual further installments of avian ecological arcana


Wade Garrett said...

Its a beautiful bird. Did it always nest like that, before foreign predators like rats were introduced into North America?

8yearoldsdude said...

predation is an endemic problem (i.e., everythign wants to eat your eggs, not just new predators), but invasive predators can often exacerbate it predation by gaining access to new areas that predators could not reach previously.

so if you are a Gannet, there are 2 places you can nest--on any steep cliff, or anywhere you want on an island that has no predators (most islands with no mammals are useless rocks in the ocean). The steep cliffs are inaccessible to predators of all types. where you get issues with invasive predators (e.g., cats or rats) is when the birds use to have the island to themselves (that is why they went there in the first place), so they nested wherever (often there are no cliffs on these rocks). and then a cat or rat was introduced by humans and went to town, because it could walk right up and eat the eggs.

Kyle said...

I'll totally have to go back to St John's when it's breeding season. Iceland too early, Newfoundland too late--I'm missing all the good East Coast birds!