John Shaw / Great frigatebird (Fregata minor) male at nest site, with gular sac inflated to attract females. Genovesa Island, Galapagos, May.

Claudio Contreras / Great Frigatebird (Fregata minor) departing from nest, San Benedicto Island, Revillagigedo Archipelago Biosphere Reserve / Archipielago de Revillagigedo UNESCO Natural World Heritage Site (Socorro Isl...

Tui De Roy / Great frigatebird (Fregata minor) male displaying inflated gular sac, Galapagos, Ecuador.

Tui De Roy / Great frigatebird (Fregata minor) male guarding single chick. Punta Cevallos, Espanola Island, Galapagos, Ecuador, May.

Cheryl-Samantha Owen / Great frigate birds (Fregata minor) sitting in tree, Aldabra Atoll, Seychelles, Indian Ocean

Tui De Roy / Great frigatebird (Fregata minor) male taking flight at dusk. Espanola Island, Galapagos, Ecuador, May.

Ingo Arndt / Great frigatebird (Fregata minor listeri) drinking freshwater on the wing, Christmas Island, Indian Ocean, Australian Territory, November

Pete Oxford / Great frigatebird (Fregata minor) male displaying, pouch inflated, Galapagos

Pete Oxford / Great frigate bird (Fregata minor) female on nest with chick, Galapagos

Pete Oxford / Great frigate bird feeding chick {Fregata minor} Genovesa, Galapagos.

Pete Oxford / Great frigate bird (Fregeta minor) male with pouch fully inflated. Orgenoves Island, Galapagos

Pete Oxford / Great Frigate bird (Fregeta minor) male courtship display. Galapagos, Tower Orgenoves Island

Tui De Roy / Great Frigatebird (Fregata minor) parent and chick on nest, Genovesa Island, Galapagos Islands, Ecuador

Tui De Roy / Great Frigatebird (Fregata minor) female guarding chick, Galapagos Islands, Ecuador

Tui De Roy / Great Frigatebird (Fregata minor) courting males vying for female's attention, Genovesa Tower Island, Galapagos Islands, Ecuador

Tui De Roy / Great Frigatebird (Fregata minor) recently formed pair, female inspecting male in courtship display with extended gular pouch, Genovesa Tower Island, Galapagos Islands, Ecuador

Tui De Roy / Great Frigatebird (Fregata minor) recently formed pair, female inspecting male in courtship display with extended gular pouch, Genovesa Tower Island, Galapagos Islands, Ecuador

Tui De Roy / Great Frigatebird (Fregata minor) male with inflated gular pouch in courtship display, Tower Island, Galapagos Islands, Ecuador

Tui De Roy / Great Frigatebird (Fregata minor) pair courting, male in full display with inflated gular air pouch, Tower Island, Galapagos Islands, Ecuador

Tui De Roy / Great Frigatebird (Fregata minor) male in courtship display with fully inflated gular air pouch, Tower Island, Galapagos Islands, Ecuador

Bruce Thomson / Male Great frigatebird (Fregata minor) in breeding condition with semi-inflated throat pouch, Christmas Island, Australia.

Bruce Thomson / Male Great frigatebird (Fregata minor) in breeding condition with semi-inflated throat pouch, Christmas Island, Australia.

Doug Perrine / Great frigatebird (Fregata minor palmerstoni) group perched in vegetation, males in courtship display with inflated red throat pouch. Eastern Island, Midway Atoll National Wildlife Refuge, Papahanaumo...

Doug Perrine / Great frigatebird (Fregata minor palmerstoni) nesting and displaying in tree alongside nesting Red-footed booby (Sula sula). Laysan albatross (Phoebastria immutabilis) chicks in foreground. Eastern Is...

Doug Perrine / Great frigatebird (Fregata minor palmerstoni) colony, males in courtship display with inflated red throat pouches. Eastern Island, Midway Atoll National Wildlife Refuge, Papahanaumokuakea Marine Natio...

Tui De Roy / Great frigatebird (Fregata minor) in tree with pair of Nazca boobies (Sula granti) showing mating behaviour, Genovesa Island, Galapagos,

David Tipling / Great frigatebird (Fregata minor) two perched on branch, St Francois Atoll, Seychelles

David Tipling / Great frigatebird (Fregata minor) in flight, St Francois Atoll, Seychelles

Tui De Roy / Tourist photographing male and female Great frigatebird (Fregata minor) Darwin Bay, Genovesa (Tower) Island, Galapagos. May 2011.

Tui De Roy / Tourists photographing displaying Great frigatebird (Fregata minor) Galapagos Islands Tourism, Darwin Bay, Genovesa (Tower) Island, Galapagos. May 2011.

Mary McDonald / Great frigatebird (Fregata minor) male, inflating red gular / throat pouch, Genovesa Island, Darwin Bay, Galapagos Islands. April.

Mary McDonald / Great frigatebird (Fregata minor) male, inflating red gular throat pouch to attract a female, Genovesa Island, Darwin Bay, Galapagos Islands. April.

Sylvain Cordier / Great frigatebird (Fregata minor ridwayi), perched on bushes, Sand island, Midway Atoll National Wildlife Refuge, Hawaii

Sylvain Cordier / Great frigatebird (Fregata minor), courtship ritual, male inflating vocal sac to attract the females, Genovesa Island, Galapagos Island.

Martin Gabriel / Great Frigatebird (Fregata minor), adult in flight, Aride Island, Republic of Seychelles

Martin Gabriel / Great Frigatebird (Fregata minor), white-headed immature in flight, Aride Island, Republic of Seychelles

Claudio Contreras / Great Frigatebird (Fregata minor) chick, San Benedicto Island, Revillagigedo Archipelago Biosphere Reserve / Archipielago de Revillagigedo UNESCO Natural World Heritage Site (Socorro Islands), Pacific...

Claudio Contreras / Great Frigatebird (Fregata minor) chick, San Benedicto Island, Revillagigedo Archipelago Biosphere Reserve / Archipielago de Revillagigedo UNESCO Natural World Heritage Site (Socorro Islands), Pacific...

Claudio Contreras / Great Frigatebird (Fregata minor) colony, San Benedicto Island, Revillagigedo Archipelago Biosphere Reserve / Archipielago de Revillagigedo UNESCO Natural World Heritage Site (Socorro Islands), Pacifi...

Claudio Contreras / Great Frigatebird (Fregata minor) with chick, San Benedicto Island, Revillagigedo Archipelago Biosphere Reserve / Archipielago de Revillagigedo UNESCO Natural World Heritage Site (Socorro Islands), Pa...

Claudio Contreras / Great Frigatebird (Fregata minor) male preening feathers, San Benedicto Island, Revillagigedo Archipelago Biosphere Reserve / Archipielago de Revillagigedo UNESCO Natural World Heritage Site (Socorro...

Claudio Contreras / Great Frigatebird (Fregata minor) adult feeding chick, San Benedicto Island, Revillagigedo Archipelago Biosphere Reserve / Archipielago de Revillagigedo UNESCO Natural World Heritage Site (Socorro Isl...

Claudio Contreras / Great Frigatebird (Fregata minor) female, San Benedicto Island, Revillagigedo Archipelago Biosphere Reserve / Archipielago de Revillagigedo UNESCO Natural World Heritage Site (Socorro Islands), Pacifi...

Claudio Contreras / Great Frigatebird (Fregata minor) colony and Barcena volcano, chick in nest, San Benedicto Island, Revillagigedo Archipelago Biosphere Reserve / Archipielago de Revillagigedo UNESCO Natural World Heri...

Claudio Contreras / Great Frigatebird (Fregata minor) chick in nest at sunset, San Benedicto Island, Revillagigedo Archipelago Biosphere Reserve / Archipielago de Revillagigedo UNESCO Natural World Heritage Site (Socorro...

Claudio Contreras / Great Frigatebird (Fregata minor) chick in nest at sunset, San Benedicto Island, Revillagigedo Archipelago Biosphere Reserve / Archipielago de Revillagigedo UNESCO Natural World Heritage Site (Socorro...

Claudio Contreras / Great Frigatebird (Fregata minor) colony, chick in nest, San Benedicto Island, Revillagigedo Archipelago Biosphere Reserve / Archipielago de Revillagigedo UNESCO Natural World Heritage Site (Socorro I...

Claudio Contreras / Great Frigatebird (Fregata minor) arriving at nest with begging chick, San Benedicto Island, Revillagigedo Archipelago Biosphere Reserve / Archipielago de Revillagigedo UNESCO Natural World Heritage S...