The Galapagos Sea Lion
is a subspecies of the California Sea Lion. They are extremely similar except that they are about one meter shorter and about 100 times less afraid of humans. We found several things interesting about the sea lions:
During mating, a bull defends his harem against all other males. What we didn´t know was that the harem is really a piece of real estate, it isn´t a set of females. Females wander from one harem to another at will. Also, the bull cannot eat while defending their territory, so each bull´s becomes weak over time and their tenure is limited.
The female sea lion has a baby every year, and the babies suckle for 3 years. It turns out that the second and third baby have a much lower chance of survival than the first. (Why would natural selection lead to this system?)
The young sea lions are like puppies in that they play with great intensity. Their play activities
are actually often practice for the challenges of their adult lives. For example they´ll wrestle each other, in preparation for fighting off other bulls so as to control a harem.
Several times we saw them practice a defense against shark attacks. One pup would poke his nose into his friend´s side, simulating a shark. His friend would shoot into the air, do a back flip, and come down on the other side of the pretend shark.
There are 3 types of boobies in the Galapagos: Red footed, Blue footed, and masked (aka Nazca boobies, who happen to have gray feet).
There is no interbreeding between the 3 types. Why would this be? That is, what difference does foot color make? And why do they have different feet color in the first place? What did the color red or blue do that helped one subspecies adapt better to its environment? We found ourselves asking a lot of questions like this when we were in the Galapagos! A 15 second video of boobies courting is here. Another of a couple walking is here.
The boobies cool themselves by fluttering the skin on the upper forward part of the neck. How could this help cool them? Booby courtship includes a rather elaborate set of dance steps where the potential partners truly appear to be flirting with each other.
The boobies lay two eggs, but only one survives. Why would this be? Video of a parent turning the eggs and then sitting on them is here.
During nest building, the male red footed booby collects nest materials and the female approves or disapproves the materials and “decorates” the nest (sound familiar?). Incubation takes 45 days, and then the baby may spend 6 months in the nest, being fed by mom and dad. In 3 years they will reach sexual maturity, and their feet will change color.
The male courts by inflating a huge red balloon under his chin. He may sit on a branch for up to a week, without food or water, waiting for some female to find his pouch attractive. When a female flies by the males all stand up, spread their wings wide, shake, and call. It´s pretty clear that they are saying “look at me babe!” Evidently the males mate every other year but the females mate every year.
The male makes a noise by rubbing his beak on his balloon. A female says yes by rubbing her beak on the male´s balloon. A video is here.
Frigate birds cannot land in the water, so they fly over the ocean night and day for more than a week at a time. They are not very good at fishing, so they often steal food from other birds – like kleptomaniacs.
Sea Turtles and Land Tortoises
Some of the data about tortoises in general, and the differences between sea turtles and land tortoises is quite remarkable. Most of the differences can be explained by the fact that sea turtles live much more active, risky lives, as compared to their land locked friends:
- Land tortoises generally can weigh up to 250 kilograms (over 500 pounds), with the largest recorded weight being 880 pounds, twice as large as sea turtles.
- Land tortoises lay up to 16 eggs at a time whereas the sea turtles lay 100 to 200.
- Land tortoise eggs are roughly tennis ball size but the sea turtle eggs are just slightly larger than ping pong balls.
Land tortoises don´t reach sexual maturity for 25 years, whereas sea turtles only take 10 years.
- Land tortoises live for about 150 years but sea turtles live for only 60 years.
- We were told that land tortoise populations consist of 3 females for every male, but sea turtles have 3 males for every female. The logic of this escapes us, if it is actually true. We did learn that if land tortoise eggs are incubated at about 29 degrees C, they tend to become female, whereas 28 degrees C yields males.
- Land tortoises mate up on the side of the mountain. The mother then walks several kilometers down to the coast where she digs a nest and lays her eggs. Green sea turtle mothers travel up to 1,600 miles to return to their birth place and lay eggs. We wonder why the land tortoise mothers make their hike to the coast. Is it because that´s the only place they can find soft dirt/sand to bury eggs in, or are they long-ago relatives of the sea turtle, still retaining its preference for coastal nests? A video of a land tortoise living in the lush foliage up on the mountain is here.
- Land tortoises have tongues that are so tough they can eat dried cactus leaves with the thorns, as easily as humans eat potato chips! Video here. Sea turtles munch on their food underwater.
Moult about 2 times per year, prior to breeding. It takes about a week, and during this time they are not likely to swim, so they don’t eat much. But they can swim to catch food if necessary to avoid starvation, since the waters are generally warm. We were told that moulting is necessary because they´d get too hot living on the equator if they did not moult, but we also read that equatorial sun causes plumage damage, so they moult to grow new plumage. These guys are endangered by global warming because their survival is dependent on the equatorial ocean currents which are altered with global warming.
Trivia question: Where can you find penguins in North America? Answer: The northern end of Isabela Island in the Galapagos, which extends just barely north of the equator.
Marine iguanas live 40 years, land iguanas live 70-80 years. This may be because there are far fewer hazards for land iguanas.
Marine iguanas are the only reptiles that can swim and eat underwater. There´s a video of marine iguanas here.
The goats on Bartolomé Island learned to drink salt water. They were pests though and were eradicated through an official program to kill them all.
Crabs are cannibals. Periodically they moult, shedding one shell and then growing another larger one. During this period of vulnerability they may be eaten by another crab.
When pelicans fish, they are followed by brown nottys. When the pelican dives into the water and fills its beak with fish, the brown notty lands on its head. Sometimes, when the pelican is straining out the water, an end of a fish slips between the pelican´s jaws and the brown notty steals it.
Waved Albatrosses are medium sized, as albatrosses go, with a wingspan of 7.4 feet. Their long wings permit them to soar effortlessly for hours, but they have trouble taking off and landing. Their preferred method of take off is to jump off a cliff.
We were fortunate to see them courting, mating, making nests, and sitting on eggs. All of this was taking place on a plateau above a cliff. The plateau was littered with rocks. One poor fellow who wanted to land and take part in the
activities kept flying by at about 10 feet off the ground. Finally he got up the nerve to land. He flared his wings, slowed down, dropped to the ground, ran a short way, and then came up with an abrupt stop when his chest came up against a boulder.
Their courting behavior is something to watch. They click their big yellow bills together left to right, circle their bills, bow, upraise their bills, and make a whoo hoo sound. They mate for life.