About 2-million years ago, much of the northeast flank of Koʻolau volcano was sheared off and material was swept onto the ocean floor (named the Nuʻuanu Avalanche) – one of the largest landslides on Earth.
The Pali is the remaining edge of the giant basin, or caldera, formed by the volcano. Mōkapu Peninsula (where Marine Corps Base Hawai‘i is situated) is evidence of subsequent secondary volcanic eruptions that formed, among other features, the islet of Moku Manu.
The majority of seabird-nesting colonies in the main Hawaiian Islands are located on the offshore islands, islets and rocks. Many of these offshore islands are part of the Hawaii State Seabird Sanctuary System.
These sanctuaries protect seabirds, Hawaiian Monk seals, migrating shorebirds, and native coastal vegetation. These small sanctuary areas represent the last vestiges of a once widespread coastal ecosystem that included the coastlines of all the main Hawaiian Islands. (DLNR)
Hawaiian seabirds today are subject to a number of threats to their survival, including predation by introduced mammals, habitat loss and degradation, and human impacts by people trespassing in seabird nesting areas.
Moku Manu (Bird Island) is three-quarters of a mile off Mōkapu Peninsula. It’s aptly named; it has the most diverse and one of the densest seabird colonies in the Main Hawaiian Islands. The state designated it the Moku Manu State Wildlife Sanctuary. (DLNR)
It is home to Uʻau Kani or Wedged-Tailed Shearwater, Noio or Black Noddy, Noio kōhā or Brown Noddy, ʻOu or Bulwer’s Petrel, Koaʻe ʻula or Red-tailed Tropicbird, ‘Ewa ʻEwa or Sooty Tern …
… ʻIwa or Great Frigatebird, Christmas Shearwater, Pākalakala or Grey-backed Tern, ʻā or Masked Booby, ʻā or Brown Booby, ʻā or Red-footed Boobies and various common shorebird species. (DLNR)
Moku Manu is protected as a state seabird sanctuary like its neighbors to the south, Manana, Kāohikaipu, and Mōkōlea Rock. “It is prohibited for any person to land upon, enter or attempt to enter, or remain in any wildlife sanctuaries …” Regardless, landing by boat is nearly impossible due to the lack of a safe beach.
The island is actually of two parts; the main western one is about 18 acres in extent and the smaller outer part is about three acres.
It has a relatively flat top, averaging about 165 feet in height but running up to 202 feet. The cliffs of Moku Manu drop directly into the sea around more than half of the island.
Moku Manu is perhaps the least accessible to humans of any of O‘ahu’s offshore islands. This fact seems to explain to an important degree the breeding of several species there that do not nest on any other of Oahu’s offshore islands.
Due to the challenging accessibility onto the island, it is rarely visited by unauthorized persons and not often by others (it is prohibited by law to go onto the island without a permit.)
During the last century or more, when the bird populations of more accessible offshore islands were depleted by man, and domestic plants and mammals sometimes introduced, Moku Manu remained relatively free from such influences.
The much longer canoe trip (there are no beaches near the head of Mōkapu Peninsula opposite Moku Manu,) the rough channel, and the uncertainty of being able to get on the island must have combined to keep even the old Hawaiians away much of the time. (Richardson & Fisher, 1950)
I grew up on Kaneohe Bay (on the other side of Mōkapu Peninsula from Moku Manu. No one sailed in our family. Except, as a pre-/early-teen, we did get a car-toppable Sunfish that I used to sail by myself in the Bay, usually in the main basin of the Bay.
However, one day I cruised to Coral Island, then ventured a bit more out the Crash Boat Channel to Turtle Back. And, from there, in the distance, I saw another target, Moku Manu.
After a while, and about halfway to Moku Manu, I realized this was probably not a good idea; folks at home thought I was leisurely cruising in the Bay, now I was in blue water, well outside the Bay.
No one knowing, no life jacket, no radio … a kid with no brains. However, the challenge was there and I eventually circled the island, and its birds, and safely headed home.