Signpost of the tropics

A 412
The distinctive black silhouette of a great frigatebird (Fregata minor) materialized beneath the swollen white belly of a towering cumulus cloud south of Christmas Island (Kiribati), near the equator in the central Pacific. Light winds filled our genoa and mainsail, Élan’s bow aiming for a point east of Bora Bora, more than 1,000 miles away. Due to our previous careers in commercial fishing, what was at first little more than a black speck riveted our attention. Abruptly, the scissor-like tail twitched, the long, graceful wings folded, transforming a lofty glide into a screaming dive for the ocean below.

Just as the frigate flared at low altitude, a half-dozen silvery flying fish sprayed skyward in response to the explosive neon-blue streak of a large mahimahi just under the waves. The airborne predator wheeled sharply and then used the remaining momentum of the descent to soar rapidly along the sea surface, gracefully snatching a flying fish in midair before climbing sharply. We eased the helm over to swing our trolled lines in front of the hungry mahimahi, and within the hour, the delicious aroma of fresh grilled fillets permeated the aft deck.

Five species of frigatebird — great, lesser, magnificent, Christmas Island (Indian Ocean) and Ascension — three with broad distributions, guarantee that seafarers will enjoy the company of these majestic seabirds throughout most tropical and subtropical areas of the world. Specific frigatebird behaviors have for centuries tipped off the presence of various offshore quarries for fishermen. A straight, relatively high flight pattern, punctuated by dips and dives, usually indicates mahimahi or billfish traveling at the surface. Erratic, low-altitude sweeps and hard turns indicate a surface-feeding school of tuna. This same behavior may actually carry seafarers away from the fish if the frigate is following the common habit of chasing terns, boobies and other species in an effort to get them to drop or disgorge recently captured fish, which the black pirate then swoops in to pluck from the sea, or to catch before it splashes.

Traditional Indo-Pacific navigators have long prized the sight of frigatebirds, a sure sign of land not too distant. While frigates may soar well offshore, beyond the range of gulls, pelicans, and most noddies and terns, their habit of nightly returning to roosts ashore means they are not truly oceanic, like albatrosses, petrels and shearwaters. Unlike these species, the oil-gland production of frigatebirds is not enough to protect their feathers from fatal saturation should they land in the drink. Does this have anything to do with their habit of hovering close to port on the windiest, roughest days?

Frigatebirds nest primarily on isolated tropical islands, often low coral atolls. Their nests tend to be large conglomerations of sticks, usually in shrubs or mangroves, often on the ground. Males initiate the process by developing a large, crimson throat sack, which they inflate and — along with bill clacks, squawks and caws, and wing stretching and flapping — attempt to lure a female to the nesting site. The pair produces a single large egg, takes turns incubating it for up to nearly eight weeks before hatching, and then actively cares for and feeds the chick for at least six months.

Frigates seem relatively indifferent to humans during courtship and nesting. We have closely approached adults and juveniles in the Line Islands and Marshall Islands of equatorial Micronesia. Some Pacific Islanders take advantage of this trait, capturing juveniles and taming them as pets. One text reports that by training these tame birds to identify certain structures with food, the owners can pass messages attached to the legs of frigatebirds released to fly to neighboring islands. Despite such services, frigates do receive the odd invitation to the dinner table, as an entrée, in this part of the world.

Throughout seafaring history the effortless grace of a frigatebird riding subtle air currents far aloft, wings spread wide and nearly motionless, circling slowly overhead, has carried different meanings for different mariners. For all of us past and present, though, like the rustle of palm fronds or a vivid coral reef reflecting through clear water, these magnificent seabirds remain a timeless symbol of the tropics.

By Ocean Navigator