I have taken the following from the
www.galapagosadventures.com site. And re whale sharks - from what I have read best chances of spotting them are earlier in the whale shark season i.e the July end rather than Later December.
January
Warm marine currents arrive.
Land birds start nesting On Espanola, the adult male marine iguanas become brightly colored
The green sea turtle arrives to the beaches of Galapagos to lay their eggs
Land iguanas begin reproductive cycles on Isabela
Water and air temperatures rise and stay warm until June
Ideal time for snorkeling
February
On Floreana flamingos start nesting
White-cheeked pintails start their breeding season
Masked boobies on Espanola are at the end of their nesting season
Marine iguanas nest on Santa Cruz
Highest water temperature reaches 25°C (77°F) and remains until April
Galapagos dove's nesting season reaches its peak
March
Water temperature reaches its max.
Sporadic tropical rains and intense sun. Air temperature can reach up to 30°C (86°F)
Marine iguanas nest in Fernandina March 21, the summer equinox signals the beginning.
The waved albatross arrive to Espanola
April
Massive arrival of waved albatross to Espanola. Their courtship starts.
Hatching season ends for giant tortoises
Green sea turtles' eggs begin to hatch
Land iguanas hatch on Isabela
May
North Seymour's blue-footed boobies begin their courtship
Sea turtles are still hatching on Gardner Bay, Punta Cormorant and Puerto Egas
Palo santo trees begin to shed their foliage
Albatross on Espanola start laying their eggs
Band-rumped storm petrels begin their first nesting period
June
Beginning of the dry season
Giant tortoises migrate from highlands to lowlands for suitable nesting places
Beginning of nesting season of giant tortoises
July
Sea birds are active, especially blue-footed boobies on Espanola Flightless cormorants court and nest on Fernandina.
It´s possible to find oyster catchers nesting on Puerto Egas
Lava lizards initiate mating rituals until November
Whales are more likely to be observed, especially off the Western coast of Isabela
August
The Galapagos hawks court on Espanola and Santiago
Masked boobies and swallow-tailed gulls nest on Genovesa
Temperature of the ocean descends to 18° C (64°F) which obviously varies according to the geographic zones among the islands.
Migrant shore birds start to arrive, and stay on the islands until March.
Giant tortoises return to the highlands of Santa Cruz
September
Peak of the dry season
The air temperature reaches its lowest (19°C - 66°F)
Penguins demonstrate remarkable activity on Bartolome until December
Sea lions are very active, specially in the western and central areas of the Archipelago
Most species of marine birds remain active at their nesting sites
October
Lava herons nest until March
The Galapagos fur seals begin their mating period
Boobies raise their chicks on Espanola
Giant tortoises still lay their eggs
November
Sea lion pups are born
Sea lions are sexually active on the Eastern part of the Archipelago
Breeding season of brown noddies
Band-rumped storm petrels begin their second nesting period
December
Hatching of the giant tortoise's eggs begins and lasts until April
Green sea turtles display their mating behavior.
The warm season begins and all of the plants of the dry zone produce leaves.
Galapagos "turns green". The first young albatross fledge
