06 December 2009

Island Ecology

Perhaps most interesting is island biogeography. Although a small part of world's avifauna, islands have had an important role in our understanding of bird evolution and ecology (remember Darwin and adaptive radiation). Islands are little experiments in evolution, and they have reduced biota making for simple community structure. Isolation form continental evolution makes it easier to see.

There are bascially two types of islands: oceanic: start with rock and gives rise to a community never connected with mainland. And continental: broke off from continent and share communities with it.
NEW ISLANDS have only a few plants, so flora depauperate. Some mainland birds are therefore excluded--only a select few can disperse to an island and, of course, you need a male and female. These must nest successfully. Migrants have to quit flying (most migrants arrive in nonbreeding condition) --physiology has to change or perhaps immatures stay (Andean and Franklin's Gulls in the highlands of Peru may be an example of this).


 
Andean (above) and Franklin's gull

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