Seabirds

Ua'u

(Hawaiian Petrel)

Photo credit: Maui Nui Seabird Recovery Project

Fun Fact:

-Once the most common seabird on the islands, there were so many that they would blot out the sky when they came back from sea onto land.

- The Hawaiian petrel is a monogamous species, and the male and female will take shifts during incubation. While incubating the egg, the bird does not have access to food and water, so it usually spends the whole time sleeping in order to minimize the loss of energy. The female lays only one egg per year.

- Unlike some seabirds, the Hawaiian petrel does not dive into the water to feed. It usually feeds by seizing prey whilst sitting on the water or picks it off the water’s surface while flapping just above, often pattering the water with its feet.

Diet:

- Adults feed on squid, fish, and crustaceans and pass food to chicks by regurgitation.

- The Hawaiian petrel mainly forages for food at night, flying in flocks with other species of marine birds. 

Status:

Endangered

- The ‘ua‘u was once abundant on all main Hawaiian islands except Ni‘ihau. Today, the largest known breeding colonies are found at Haleakala Crater on Maui and on the summit of Lana‘i. Other colonies are on Kaua‘i, the island of Hawai‘i, and possibly Moloka‘i.

- Threats to this endangered seabird include predation by introduced mammals, development, light attraction and collision, ocean pollution, and disturbance of their breeding grounds.

- The petrel does not have any natural defenses against predators such as rats, feral cats, and mongooses, and their burrows are very vulnerable.

 

Ua'u Kani

(Wedge-tailed Shearwater)

Photo credit: Maui Nui Seabird Recovery Project

Fun Fact:

- Produces a variety of wails and moans that surely inspired the Hawaiian name of this bird which means “calling or moaning petrel.” They can sound like crying human babies.

- Can dive 150 ft. underwater.

- Drinks salt water, filters it internally, and then excretes the salt through their nares.

 Diet:

-  In Hawaii, diet primarily consists of larval goat fish, flying fish, squirrel fish, and flying squid. 

- Ua‘u kani use a variety of foraging techniques, most frequently plunges head into water while on the wing, also seizes prey will sitting on the water; often follows fishing vessels.

 Status:

- Common but protected under migratory bird act

- In Hawai‘i, population estimated at 270,000 breeding pairs 

 'A

(Brown Booby)

Photo credit: Mike Pazzani

Fun Fact:

 - Meaning “white stomach”, the Latin name of the brown booby is a reference to its striking white lower breast and belly,

- Once formed, breeding pairs may remain together for many years, continually reusing the same nesting site. Displays by members of pair include bill-touching, bowing, throwing head back with bill pointing skyward.

- The brown booby usually breeds at an age of four to five years, and may live for over 25 years.

Diet:

- In North American waters, diet includes flying fish and mullet, also squid and shrimp. 

- Foraging is frequently carried out alone or in small groups, by flying over inshore waters while searching for shoals of small fish driven to the surface by marine predators.

-Techniques used to catch prey include diving at a shallow angle and snatching prey from the surface, as well as steep plunge dives from up to 20 meters above the water surface, reaching prey over two meters below.

- Some individuals also snatch unwary fish while floating on the surface, or steal food from other seabirds.

 Status:

 -Brown Booby populations are declining.  

- Considers it a Species of High Concern.

- Brown Booby are on the 2014 State of the Birds Watch List which lists bird species that are at risk of becoming threatened or endangered without conservation action. 

A'o

(Newell's Shearwater)

Photo credit: Brenda Zaun

Fun Fact:

- The Newell’s shearwater is a medium-sized shearwater measuring 12 to 14 inches with a wing span of 30-35 inches.

-  Its claws are well adapted for burrow excavation and climbing.

- A'o have a loud and nasal call that resembles the braying of a donkey and the call of a crow.

- The age at first breeding is likely to be around six or seven years.

 Diet:

-The ‘a‘o primarily feeds on squid and fish.

 Status:

- Endangered

- The Newell’s shearwater was once abundant on all main Hawaiian islands. Today, the majority of these birds nest primarily in mountainous terrain between 500 to 2,300 feet on Kaua‘i.

- This seabird was reported to be in danger of extinction by the 1930s. The introduction of the mongoose, cat, black rat, and Norway rat may have played a primary role in the reduction of ground nesting seabirds such as the ‘a‘o and the ‘ua‘u (Hawaiian petrel).

 

 Koa'e Kea

(White-tailed Tropicbird)

Photo credit: Glen Tepke

Fun Fact:

- The white-tailed tropicbird is the smallest of the tropicbirds, a group of elegant seabirds renowned for their greatly elongated tail streamers.

- This is the national bird of Bermuda, where the "Longtail" is familiar to all and is given complete protection.

- Courtship displays include two birds flying gracefully in unison, one above the other, with higher bird bending tail down to touch tail of lower bird.

- Tropicbirds are remarkable for being able to remain at sea for indefinite periods, and can sustain long periods of flight.

Diet:

-Forages by plunging into water from flight, submerging briefly; sometimes by swooping down to surface without striking water, perhaps taking flying fish in the air. May feed most actively in early morning and late afternoon. Feeds on a wide variety of small fish, but seems to favor flying fish, which are common in tropical waters. Also eats small squid, snails, crabs.

Status:

- This species is classified as Least Concern (LC) on the IUCN Red List

- Protected under migratory bird act

 

Layasan Albatross

Photo credit: Cameron Rutt

Fun Fact:

Albatross have the 2nd largest wingspan in the avian kingdom.

- These expert soarers can travel hundreds of miles per day with barely a wing beat.

- Laysan Albatrosses live very long lives. They usually don’t start breeding successfully until they are 8 or 9.

- The oldest known individual was 65 years old, when she was identified in 2016 by the band on her leg while she was at her nest.

- Adults with chicks to feed take foraging trips that last up to 17 days and travel 1,600 miles away from their nest (straight-line distance).

 Diet:

 - Laysan Albatrosses eat mainly squid as well as fish eggs, crustaceans, floating carrion, and some discards from fishing boats.

 Status:

 - Laysan Albatrosses as with all albatross species there are serious threats to their population, and this species is on the 2014 State of the Birds Watch List. 

 - Laysan Albatrosses face threats from longline fishing, plastic trash in the ocean, and predation by dogs, rats, and cats.

 

References and further reading

http://kauaiseabirdproject.org/

https://www.nps.gov

https://abcbirds.org

http://www.audubon.org/

http://www.arkive.org

http://www.birdlife.org

http://identify.whatbird.com/

https://www.allaboutbirds.org

http://www.birdweb.org/

https://www.fws.gov

http://dlnr.hawaii.gov/wildlife