Australia’s endangered species: Christmas Island frigatebird

The Christmas Island frigatebird is a large, spectacular seabird. It is one of only five species of frigatebirds, all of which have glossy black plumage, narrow wings, light and agile flight skills, and a long bill with a hooked end.

Three species (great frigatebird, greater frigatebird and lesser frigatebird) are widespread in tropical oceans. Ascension Island Frigatebird Each species only occurs on one island, and what’s even more bizarre is that the Christmas Island frigatebird shares an island with the greater and lesser frigatebirds.

Christmas Island is home to many species found nowhere else, the result of millions of years of isolation and relatively recent human settlement (the 1880s).

The frigate bird is probably best known for KleptoparasitismThis piratical tendency, along with their large size, black silhouette, and skilled flying skills, earned them the honorific name of “warbirds” among early sailors.

Another characteristic of the frigatebird is the bright red throat pouch of the male. Male group display They inflate this tentacle like a grapefruit-sized balloon, then tilt their head back and tap it with their beak to entice females to fly by, away from possible nesting sites (the tree canopy).

status

The Christmas Island frigatebird has many endangered characteristics. They breed only on one island, reproduce slowly (females breed every two years, and chicks require parental care for at least 15 months), and have a relatively low reproductive success rate. Their population size is small and has been declining for decades.

It is listed as critically endangered under the Environmental Protection and Biodiversity Conservation Act and internationally (IUCN Red List).

threaten

William Dampier first visited Christmas Island in 1688, collecting “as many Boobies and Frigate-birds as could be cooked enough for all on board.” Early settlers followed suit.

Despite gradual control of catches, the population declined rapidly, from a natural breeding base of 6,200 pairs in the 1890s to around 3,300 pairs in the 1940s. (Note that population estimates are difficult because the two-year breeding cycle means that some individuals do not appear in any given year.)

Since 1980, most of the island has been designated a national park, prohibiting hunting. However, the number of frigatebirds has continued to decline, from 2,300 pairs (per year) in 1970 to 1,200 pairs in 2005. Statistics show that the number of frigatebirds continued to decline between 2008 and 2011.

Since settlement, Christmas Island’s rich heritage of endemic species has been rapidly disappearing. About 25% of the island’s rainforest has been cleared for phosphate mining. Phosphate dust once covered trees in one of the few breeding sites for the frigatebird, and this pollution may have contributed to the site’s disappearance.

The settlement brought a lot Unwanted plants and animalsOvergrown creepers now smother nesting trees and entangle birds. Yellow Crazy Ant Now cats and rats are swarming in the tree canopy, and cats and rats are causing declines in other seabirds, creating opportunities for kleptoparasitism.

But the species faces wider problems. When not breeding, it ranges widely from Christmas Island north to the Philippines, where it faces risks from hunting, entanglement in fishing tackle, depletion of fish stocks and habitat loss on islands that serve as transit points.

strategy

The survival of the Christmas Island frigatebird depends on reversing the degradation of its restricted breeding habitat. But it also migrates easily across existing political boundaries. Like many other widespread species, its conservation requires international cooperation.

A recovery plan was drawn up in 2004 but little has been implemented and the continued decline has proven a failure.There has been some research into recovery plans, mainly by David James and Janos Hennicke, and more recently with some funding from Australian Geographic.

A regional recovery plan for Christmas Island biodiversity is under development and may provide a more strategic and effective approach if adequately resourced.

in conclusion

The Christmas Island frigatebird epitomizes biodiversity at its most wondrous and challenging. It is perfectly adapted to a specific robust ecological role, but is highly vulnerable in other traits. It illustrates the role of islands as engines of evolution, but also the fragility of these sites. It shows that we have an opportunity to correct our ancestors’ thoughtless and irresponsible attitude toward nature. Perhaps most importantly, it is an example of the need to complement local-scale conservation strategies with collaboration across borders.

The Conversation is publishing a series of articles on Australia’s endangered species. View here