Frigatebirds

Frigatebird/ Fregata sp. / Family - Fregatidae /

Frigatebirds are the most aerial of tropical seabirds.

Their alternative name - 'man-of-war' - stems from their habit of chasing other seabirds until they regurgitate their recently collected fish or squid. The frigatebird usually catches the falling food before it hits the sea.

Adult males are all black, with bright red throat patches, which inflate into balloons during display. Females have partly white underparts, varying depending on the species. Babies have white heads.

Distinguishing features of both males and females include long wings, slender sharply hooked bills, and long deeply forked tails. They have short legs designed for clinging rather than walking.

Habitat

Frigatebirds spend most of their time soaring high in search of prey, or nesting on islands. Nests are usually built on top of low trees, bushes or on the ground, where vegetation is absent. Frigatebirds nest close to other seabird colonies so they can harass them for food. The nests are untidy, built from sticks, feathers and other material. Both parents build the nest.

Reproduction

The female is courted and mated. The male helps in nest making while the female guards the nest in preparation for laying a single white egg. Upon production of a single white egg the male takes over the incubation while the female, after fasting during the long courtship and guard period, flies away to feed at sea for up to ten days.

The chick is naked when born and later covered in grey down. It can take 4 to 5 months to fly but the period of dependence on the adult for food may take longer.

Feeding

Frigatebirds never land on the water and feed by snatching up surface marine food and scraps or harassing other seabirds until they disgorge their catch. They are also known to prey on unguarded eggs or young chicks from nesting colonies of other seabirds.

Threats

Great care should be taken when visiting known breeding grounds for seabirds. Walking or sitting carelessly can destroy eggs or chicks. Some birds are easily frightened and may abandon their eggs and chicks.

Apart from human disturbance, natural pressures such as storms and cyclones also affect seabird numbers. The effects of these natural events can be considerable, but can be tolerated because they are irregular. Unfortunately careless human activity is much more likely to delay or prevent a colony's recovery from natural disasters.

There are many ways we can protect birds and their habitats:

• During the breeding season, some islands of the Great Barrier Reef are closed to all visitors. For example, the Brook Islands are completely off limits during summer to protect the thousands of Pied Imperial Pigeons that migrate from Papua New Guinea to nest there.
• Special fire regimes are in place to manage vegetated islands and cays.
• Preservation of the mangrove forests is vital, not only for birds and other animals, but also to maintain the natural tidal flows and to offset the destructive effects of cyclones.
• Pollution control is necessary to protect the Reef from excessive sediment, rubbish and waste that affect critical mangrove, mudflat and inner reef habitats, and alter food supplies.
• Controlling feral animals will help to reduce predation on nesting birds and young.
• Control of introduced plants will allow native vegetation to regrow.
• Controlling beach access and vehicles on sand dunes will help to maintain these features and protect vulnerable ground-nesting birds. Dunes are a natural part of beaches and are our first line of defence from coastal erosion due to rising sea levels.