Blue Footed Boobie


By Aidan MacLeod

aidan.jpg (14837 bytes) I have done this report with the intention that it makes up for some of the missing science in my program. I have (perhaps intentionally) only been sent blocks 2 and 3 but please do not think that I am demanding that you send them. I am perfectly fine with completing my science through reports like this one. I compiled the information for this report at the Mexican bird sanctuary Isla Isobela, (approximately North 25 deg 50 min, West 105 deg 53 min) in a day and a half’s observations. The statements I make could be completely incorrect. I chose the blue-footed booby for research because, due to their stationary and fearless nature, they were by far the easiest and most interesting bird to research.

Blue-footed boobies usually nest with several other nesting females in what I have termed a nesting colony. These colonies contain anywhere from 2 to 20 nesting females. The nests are mostly made of dead grass piled into a circle on the ground, although sometimes they are shallow holes in rock. There were few males in the nesting colonies that we saw. Although blue-footed boobies are aquatic birds, their nests are sometimes quite far from water. Blue-footed boobies have 2 to 3 chicken size eggs, which are (perhaps from dirt and dust) brown in colour and sometimes white. The nesting female has a varying fear of humans. Some females will run from their nest and leave eggs unguarded before you come within 20 feet and some will not move even if you are within one foot of them. Most boobies with eggs will run from you but ones with young will never move. Booby mothers will sometimes wedge their young under their winds when threatened. Having never seen that before I now see the expression "Taken under her wing" in a whole new light. It looks quite suffocating! When the chicks are young they are featherless, curious, and sat on like eggs. The chicks eat by having their parents regurgitate fish for them. At a certain point the chicks become too big to be sat on and instead wedge themselves in beside their mother. By this time the chicks are white and fluffy. By the time their feathers start to change they are alone. I suspect they are flightless until all of their feathers change. During this changing period they are quite ugly. One of the most interesting things we found while on Isla Isobela was the varying stage of maturity among chicks. For example, at one nesting colony most of the mothers may have eggs and there would be few females with young, while another nesting colony will be mainly white chicks and no eggs. We speculated that the varying egg and chick maturity difference may have something to do with how much weather exposure the different colonies get.

Blue-footed boobies are a variety of gannet. They are alike in shape and slightly smaller in size. According to my field guide blue-footed boobies are 26 inches in length and have a wing span of 64 inches. However, the boobies we saw did not seem to have a wingspan longer than I am tall. They seemed to be around 18 inches long to us with perhaps a 42 to 50 inch wingspan. The most distinguishing thing about the blue-footed booby is their almost electric blue webbed feet. Even without any other information you can always spot a blue-footed booby. They have a black, sometimes slightly blue bill, which takes up most of their face. The neck and head is white on the outside and black on the inside so colour is determined somewhat by angle. The neck is also slightly elongated compared to a gull’s but not as much as a cormorant’s. They have a white chest and underbody and brown wings. There is a large size difference between the females and males of the blue-footed booby. Some of the nesting females seemed over two feet long while the males seemed just over a foot and a half long.

bluefoot3.jpg (4830 bytes) Blue-footed boobies eat small, minnow-like fish. They catch these fish by flying high and diving into the water. They can swim up to 50 feet underwater in pursuit of the fish. Sometimes frigate birds will try to attack boobies who have caught fish to steal their food. Also, frigate birds will sometimes dive-bomb injured boobies, for what reason I’m not sure. Other than these minor attacks we found no creature on the island that made predator moves towards the blue-footed booby, although they would
seem very easy targets. For instance, if you approached two nesting blue-footed boobies, it is very likely that one or both of them would hold their ground until you are close enough to grab them. I am sure that if there had been primitive humans on Isla Isobela the booby population on the island would be severely diminished.

The only way for me to explain the blue-footed booby’s habitat is to explain where they nested. Some of the nests were in thin and dry forest, while others were on rocks by the shore. Some others were on the soil at the top of the cliff and in short grass. Some places we didn’t see them was in the thicker forest or jungle, the direct shore, long grass and in trees.

One of the better things about doing research the way I have, is that you observe more firsthand behavior of the animal you are researching. These are all things I found interesting in the behavior of the blue-footed booby. Blue-footed boobies (or at least nesting ones) make two different calls. One is a cross between whonk and a squawk, which is most easily credited to the blue-footed booby and the other is a shrill whistling which we found hard to connect to the birds. Perhaps they have different meanings like a warning and a panic signal? Sometimes when we were approaching a booby nest the male (in the rare occurrence that he was present) would awkwardly hobble away in the opposite direction of his nest to draw a potential predator (in this case me) away from his mate and chicks, relying on the predator instinct of only attacking the old, young, injured or sick. The booby is, of course, not injured and much more able to escape than his young-protecting mate. A very strange but common act committed by the blue footed booby is when a male is near his mate, he will often pick up some dried grass or straw from the ground and pass it back and forth between him and his mate, the female sometimes taking the straw and setting it in their nest or on the ground. This will sometimes be repeated again and again and is quite amusing to watch. Many times during our hike around Isla Isobela we found ourselves close enough to a booby that he should fly away but would not because of the cliff behind him. No matter how close we got to the booby, he would not fly away. The frigate birds, gulls and pelicans would but not the boobies.

In conclusion, blue-footed boobies were very interesting to observe and I greatly enjoyed researching in a new way.

A little about our author:

Aidan MacLeod is 12 years of age and comes from Victoria, British Columbia, Canada. He, his brother and parents are sailing in the Pacific and we met him in Hiva Oa, Marquesas, French Polynesia. Aidan takes part in a Home Study School where he independently works and forwards his schoolwork to teachers back in Canada. Aidan was good enough to share is independent study report on the Blue-Footed Booby.

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