Genovesa Island
Today was a true paradise for birders, as the island sometimes referred to as Hitchcock’s Island combines a series of factors perfect for large colonies of seabirds. As we learned today from National Audubon guest lecturer, Steve Kress, over 90 % of all marine birds nest in colonies, for several reasons. Amongst these are predator protection, proximity to good feeding grounds, perfect nesting conditions and other social reasons. Genovesa is the perfect place for seabirds, and contains, amongst others, enormous colonies of red-footed boobies. Though we had hardly come across this colorful bird until today, it is by far the most numerous booby in Galapagos, numbering approximately 700,000 on this island alone! Being oceanic birds, the northernmost islands are closer to their feeding grounds, but the main reason we had not seen them before today was the presence of our one important native predator, the Galapagos hawk. Because Genovesa Island is separated from the central archipelago by deep waters, it never joined to other islands by land bridges, even during past ice ages. The central islands are separated by relatively shallow waters, so when the sea level was lowered, the spreading of terrestrial reptiles such as the lava lizard, main food source for the hawk, was facilitated.
Other large breeding colonies on the island include the Nazca booby, the wedge-rumped storm petrels, red-billed tropic birds and our wonderfully unique swallow-tailed gulls. This gull, Creagrus furcatus, is the most beautiful gull in the world (admittedly, I am besotted by the Galapagos, so not particularly objective), with its red feet and crimson eye ring which set off the wonderfully textured black, gray and white plumage. This bird is so markedly different from other gulls, in many features of its biology and behavior, that it has been placed in a genus of its own. The most remarkable difference is that it is the only nocturnal gull in the world, leaving its colonies at dusk, amidst much screaming and display, to feed on the squid that rise to the surface at night. There are around 10,000 to 15,000 pairs of this magnificent bird in Galapagos, which constitutes practically the world population of the species, and each pair attempts to breed every ten months or so. It was an incredible honor to walk amongst these breeding colonies, getting close to the action and observing the clever nests the birds make. Swallow-tailed gulls collect pebbles and shells of different sizes and colors, which they arrange so as to make speckled nests which perfectly camouflage their one, large speckled egg.
Today was a true paradise for birders, as the island sometimes referred to as Hitchcock’s Island combines a series of factors perfect for large colonies of seabirds. As we learned today from National Audubon guest lecturer, Steve Kress, over 90 % of all marine birds nest in colonies, for several reasons. Amongst these are predator protection, proximity to good feeding grounds, perfect nesting conditions and other social reasons. Genovesa is the perfect place for seabirds, and contains, amongst others, enormous colonies of red-footed boobies. Though we had hardly come across this colorful bird until today, it is by far the most numerous booby in Galapagos, numbering approximately 700,000 on this island alone! Being oceanic birds, the northernmost islands are closer to their feeding grounds, but the main reason we had not seen them before today was the presence of our one important native predator, the Galapagos hawk. Because Genovesa Island is separated from the central archipelago by deep waters, it never joined to other islands by land bridges, even during past ice ages. The central islands are separated by relatively shallow waters, so when the sea level was lowered, the spreading of terrestrial reptiles such as the lava lizard, main food source for the hawk, was facilitated.
Other large breeding colonies on the island include the Nazca booby, the wedge-rumped storm petrels, red-billed tropic birds and our wonderfully unique swallow-tailed gulls. This gull, Creagrus furcatus, is the most beautiful gull in the world (admittedly, I am besotted by the Galapagos, so not particularly objective), with its red feet and crimson eye ring which set off the wonderfully textured black, gray and white plumage. This bird is so markedly different from other gulls, in many features of its biology and behavior, that it has been placed in a genus of its own. The most remarkable difference is that it is the only nocturnal gull in the world, leaving its colonies at dusk, amidst much screaming and display, to feed on the squid that rise to the surface at night. There are around 10,000 to 15,000 pairs of this magnificent bird in Galapagos, which constitutes practically the world population of the species, and each pair attempts to breed every ten months or so. It was an incredible honor to walk amongst these breeding colonies, getting close to the action and observing the clever nests the birds make. Swallow-tailed gulls collect pebbles and shells of different sizes and colors, which they arrange so as to make speckled nests which perfectly camouflage their one, large speckled egg.
