
Contents of this page: Geology of the Galápagos Islands , Galápagos Sea Lion , Blue-footed Booby , Swallowtail Gull , Masked Booby , Prickly Pear Cactus Tree , Galápagos Giant Tortoise , Frigatebird , Bottle-nosed Dolphin , Heron , Pelican , Vermilion Flycatcher , Lava Lizard , Galápagos Land Iguana , Galápagos Sea Iguana
In 1959, Ecuador declared 97% of the land area of the Galápagos Islands to be Galápagos National Park, which UNESCO registered as a World Heritage Site in 1978. In 1986, Ecuador added a Marine Reserve to protect the surrounding waters, which were registered in 2001 as another World Heritage Site.
Female sea lions can choose a bull for mating, and can roam from the beach of one dominant bull to another. Females become sexually receptive about three weeks after giving birth, and males fight most severely over territory about this time. Most male sea lions lack a harem, and they frequently challenge the dominant bull with posturing, barking, pushing, or biting to try to gain territorial rights. When not challenging dominant bulls, the bachelor males usually gather in relatively peaceable bachelor colonies on less desirable areas of the coast, such as rocky cliffs.

Left: Blue-footed Booby male on left and female on right. A dark
pigment surrounding the female's eye pupil makes it look larger than
the
male's.
Below right: Blue-Footed Booby male shading his egg on a
typically
spartan ground nest.

Male Blue-Footed Booby on nest with two chicks.

Blue-footed boobies lay one to three eggs about three to five days apart. After the chicks hatch, the parents feed the largest chick first, which is usually the first born. If food is in short supply, the larger chick out-competes its sibling, causing the smaller chick to starve. Sometimes the larger chick forces its sibling out of the nest, and the parents won't allow the displaced chick to return. Although this behavior seems harsh, it helps guarantee enough food for the remaining chick to survive during hard times.
Both male and female blue-footed boobies share the responsibility to bring fish to their chicks. The naked hatchlings require a parent on the nest at all times for protection and temperature regulation. After the chicks grow a coat of white down and can pant to cool themselves, both parents may risk leaving the chicks to go fishing. Frigatebirds, hawks, and owls may take unguarded chicks. However, the chicks soon grow too large to be threatened by predatory birds.

Left: Male Blue-Footed Booby. Galápagos Islands,
Ecuador.
Below right: Blue-footed Booby.


Masked Booby with egg in bare ground nest.
Masked Booby pair.

Below right: Andando sailboat. Galápagos Islands, Ecuador.

Left: A 5-foot long Galápagos Tortoise walks by two prickly pear cactus trees. Santa Cruz Island, Galápagos Islands, Ecuador. [Published in Wilderness Travel 1990 Catalog.]
Along with other members of the turtle order, Galápagos giant tortoises have a bony shell which is fused with their ribs and some other skeletal bones. The plates of the shell grow at the outer edges, but the rings gradually wear away and cannot reveal a tortoise's age. Galápagos giant tortoises may live up to 50, 150, or even 200 years, but no one knows for sure. The growth of large lichen and fungi patches on the shells of older tortoises hints at their great age. Because tortoises cannot mate until age 20 to 25, and because they live life in the slow lane, they can most likely outlive humans.
Despite the tortoise's extensive body armor, the exposed skin attracts parasites such as ticks. To eliminate parasites, tortoises (and iguanas) have adopted a mutually beneficial cleaning relationship with mocking birds and finches. When a tortoise wishes to be cleaned, it stands erect to expose all skin areas, as shown in this photograph. The mocking birds and finches have learned that tickling the tortoise's neck tells the tortoise to stretch out and expose tasty ticks and mites.
Since the Galápagos Islands formed several million years ago, enough time has passed for a number of hardy reptile species to drift by and gain a foothold. Rafts of vegetation released by flooding rivers have been known to carry animals for hundreds of miles. The giant tortoise originally came to the Galápagos Islands from continental South America, probably floating for two weeks in the prevailing westward ocean currents. Genetic studies indicate that the fourteen subspecies of Galápagos giant tortoises evolved from a common ancestor that probably first colonized San Cristóbal Island. From there the tortoises spread to the other Galápagos Islands, such as to the cloud forests atop the volcanoes of Isabela Island. Each of the five volcanoes of Isabela Island have been sufficiently isolated to support the evolution of their own distinct subspecies of Galápagos giant tortoises.
Four out of the original fourteen subspecies of Galápagos giant tortoises were decimated by whalers, sealers, and settlers, and are now extinct. To restore remaining tortoise populations, the Charles Darwin Research Station on Santa Cruz Island raises baby tortoises up to age five, when they reach a size safe from most predators. Scientists repatriate each tortoise subspecies to its native island or volcano. Each subspecies has a uniquely shaped shell. On dry islands, tortoises have saddle-shaped shells which allow them to reach high into the sparse vegetation. On wetter islands that have plentiful low vegetation, tortoises tend to have low, helmet-shaped shells. This distribution of giant tortoise subspecies greatly influenced Darwin's theory of evolution. Through natural genetic variation and natural selection, each tortoise subspecies evolved a unique shell shape that better survived local conditions.

Magnificent Frigatebird with his bright red pouch displayed.

Magnificent Frigatebird male flying with his bright red pouch
displayed.
Young Magnificent Frigatebirds in their nests.
Left: Galápagos Land Iguana.

The sea iguana feeds off red and green algae found underwater and in intertidal zones. As a consequence of its high salt intake, the sea iguana has evolved the most effective salt glands of any reptile. The iguanas sneeze the salt out of their nostrils, which often leaves their heads encrusted in salt. During breeding season, which varies island to island, males show brighter colors and aggressively defend their territories.
SEA IGUANA GALLERY: |
![]() Sea Iguana on rock. |
Colorful Sea Iguana. |
![]() Sea Iguanas sunning near blowhole. |
![]() Sea Iguana |
![]() Female sea iguana digging nest |
![]() |
![]() Sea Iguanas and Sally Lightfoot Crab. |
![]() Colorful Sea Iguana spines. |
![]() Sea Iguana head closeup. |
![]() Sea Iguanas grazing on seaweed & algae. |
![]() Me and a wild and fearless Sea Iguana. |
![]() Sea Iguana |
![]() Old male Sea Iguana. |
![]() Mature male Sea Iguana |
![]() Male Sea Iguanas in breeding colors. |
![]() Sea Iguana female. |
![]() Sea Iguana slouched on rock. |
![]() Sea Iguana resting leg. |
Reference: Galápagos, a Natural
History,
by Michael Hume Jackson. University of Calgary Press, Canada, 1993.
Contents of this page: Geology of the Galápagos Islands , Galápagos Sea Lion , Blue-footed Booby , Swallowtail Gull , Masked Booby , Prickly Pear Cactus Tree , Galápagos Giant Tortoise , Frigatebird , Bottle-nosed Dolphin , Heron , Pelican , Vermilion Flycatcher , Lava Lizard , Galápagos Land Iguana , Galápagos Sea Iguana
Copyright 1986 & 1994 by Tom Dempsey. Photographs or text may not be copied without permission.