Sunday, September 24, 2006

 

A Pound of Fish

My son had said before our leaving on this trip that he would be thrilled to see anything, whatever happened to come our way--after all, this was an expedition, not a museum, and there were no guarantees--with only one specific request. He really hoped that this would be his chance to see a frigate bird. Frigate birds are common enough on the Galapagos; however, my son wanted to see not just any frigate, but one with his bright red throat sac wobbling at full inflation. Male frigates swell their throat sacs as a mating display. I wasn't sure how much influence I was going to be able to have over this.

Fortunately, mating turns out to be a year-round proposition for many animals in the Galapagos, frigate birds included. The weather changes so little between seasons and the environment is so unforgiving that most creatures take an opportunistic view of things. When food is plentiful, some of them will happily mate several times in a year.

There are two species of frigates on the Galapagos, the Greater Frigate and the Magnificent Frigate, but they look and act similarly enough that the distinction, while I am sure it is important, is largely lost on me.

Frigates are spectacular gliders that hang in the air like shadows. There are other beautiful flyers in the Galapagos, particularly the exquisite tropic bird, but you can always feel the athletic force pushing their swoops and dives, while frigates hardly seem to move their bodies. They hang; they turn, slowly, through the sky. And then they tilt their notched shapes, only a slight shift--and have in that instant already flicked through a hundred yards and whipped past some thumping booby huffing along. It was only later, when I watched a booby fly by itself and realized how elegant and efficient it is, that I started to understand how beautifully a frigate bird navigates through the air.

Sometimes frigates also knock slower birds on the head to force them to vomit up their last meal, which the frigate then swallows in flight. This maneuver, called "kleptoparasitism," has earned them the nicknames man o' war bird and pirate bird--and no doubt others.

They are not small animals, more or less goose-sized (the Greater Frigate seems to be, as one might expect, somewhat larger), which makes their buoyancy in the air all the more startling. To keep their bodies so light, frigates' bones are as thin as drink-straws and their feathers, unlike those of most fisher-birds, are dry and fluffy rather than oiled and sleek.

Their nests start out functional although not particularly lovely and quickly degenerate, torn apart by their movements and caked in their excrement. Frigates will use almost anything as building materials. I saw a frigate squatting in a nest woven out of a tangle of bones, as if birds had their ogres too.

Frigates can barely walk--unlike sea lions, who are ungainly but effective on land, frigates are ungainly and helpless--and cannot swim at all. Although fish make up almost all of their diet, frigates are limited to scooping them from the surface of the water or, as mentioned before, knocking them out of other birds' gullets. That they cannot swim is not the only problem. They need at least a short drop in order to glide into the air, and so they cannot take off from the surface of the water. Also, their dry, unoiled feathers are not waterproof, so if a frigate is sprayed by even a few droplets, he will plunge into the sea and die. The odds seem very bad; but I saw many frigates fishing, and I saw none fall.

Comments:
I have seen a frigate bird at a distance in Cayman but never knew how fragile they really are. They seem so impervious as they reigh over the air.
 
Likewise, I saw one on St. John in the VI and had no idea it was so fragile. He had his big "sexy" red pouch very visible.
 
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