Wednesday, February 20, 2013

Really Weird Birds: Part 12

Frigatebirds, also called Man of War birds or Pirate birds, are truly masters of the sky. 

There are five species in this amazing family (Fregatidae)--the Magnificent Frigate, the Great Frigate, the Ascension Frigate, the Christmas Frigate, and the Lesser Frigate.  They are large seabirds that are found in tropical and subtropical ocean habitat.
Frigatebird range shown in blue.
They were given their nicknames due to their aggressive behaviors toward others birds.  While in flight, Frigates will poke and bite at other birds in order to steal their food.  Even worse, Frigates will sometimes grab other seabirds in flight by their tail feathers and shake them until they drop their meal or regurgitate a recently swallowed meal!  This is called Kleptoparasitism, parasitism by theft.
 Great Frigatebirds chasing a Red-footed Booby in order to steal its food.
Frigatebirds have the ability to fly extremely well and have excellent aerial control.  The reason for this is their wingspan.  These birds have the longest wingspan for their weight compared to any other bird.  For example, the largest species, the Magnificent Frigatebird, can have a wingspan of up to 7.5 feet and weighs only 3.3 pounds.  In comparison, a bald eagle with that same wingspan of 7.5 feet would weigh 12 to 14 pounds.
 A male Magnificent Frigatebird in flight.
 Birds have an oil gland, called the uropygium, at the base of their tails.  Birds spread the oil from this gland on their feathers to help their feathers stay waterproof.  Frigatebirds only have a small oil gland and thus their feathers have little waterproofing.  So they cannot dive into the water, let alone swim in it like some other seabirds.  They will capture their prey by snatching it out of the water with their long beaks.  They will also use their superb aerobics to catch flying fish out of the air.

These birds cannot walk well either, and will spend most of their time in the air, only landing to roost, breed and nest on trees or cliffs.  They can stay in the air out at sea for more than a week!  Frigatebirds are the only seabirds in which the males and females are noticeably different.  Both have iridescent black feathers as adults, but females have a white underbelly and males have inflatable red throat pouches called gular sacs.
 Breeding pair of Great Frigatebirds.  
Frigatebirds are seasonally monogamous and the males perform courtship displays for the females.  The females fly above as the males perch on the tops of trees.  The males will inflate their red throat pouches, flap the ends of their wings and shake their head.  When a male is chosen, the female will land by him and the male will respond by wrapping his wings around the female to protect her from other males.  Click here to see a video of a male Great Frigatebird trying to attract a mate.
 Male Great Frigatebird on display. 
The Ascension Frigatebird is listed as vulnerable and the Christmas Frigatebird is listed as critically endangered by the IUCN Red List of Threatened Species.  The Christmas Frigate is only found on Christmas Island in the Indian Ocean.  Habitat loss, over-fishing, marine pollution, and entanglement in fishing nets are all causes for their decline.  Also, the accidentally introduced Yellow Crazy Ant attacks and eats newly hatched chicks.  This ant has devastated the wildlife and ecology on the island. 

If you want to help endangered birds, the World Bird Sanctuary’s mission is to secure the future of threatened bird species in their natural environments.  You can help us fulfill our mission by simply visiting us and spreading what you’ve learned, becoming a member or friend, or adopting-a-bird, which feeds that bird for a year!

Submitted by Sara Oliver, World Bird Sanctuary Naturalist

No comments: