The fascination of the Galapagos Islands is that each island is so different. Each has its own wildlife, and will change depending on the time of the year and climatic conditions. For more details of variations during the year, see Galapagos calendar. One has to bear this in mind when visiting each island. Birds that nested on one island the year before, might have moved to another island finding better conditions there. Or the waved albatross who - just when you came to see them - may have already left their nesting site on Hood Island a few weeks earlier than expected!
But in return, one experiences the living laboratory of evolution at work. Most of the islands have only official visitor sites, established by the Galapagos National Park Service in conjunction with the Charles Darwin Research Station. These are areas where, accompanied by a licensed guide, tourists may enter. Visitor sites are typically delimited by a series of trail markers.
From time to time some visitor sites get closed, new ones opened. A typical Galapagos Islands tour lasts one week. The islands of Pinzon, North Plaza and Daphne Minor are off-limit islands