Brown Noddy

(Anous stolidus)
Hawaiian Name: Noio koha
Brown Noddy

The Brown and Black Noddies are two species of medium-sized terns found in tropical oceans worldwide. The overall plumage is dark with a white cap, the opposite pattern of all other tern species. In fact, noddies are thought to be the most ancient of all tern species, being closely related to gulls. Brown Noddies are the largest and most widespread of the world’s four noddy species, being found in tropical areas of the Pacific, Indian, and Atlantic Oceans. In Hawaiʻi, Brown Noddies are found breeding in large numbers on all of the Northwestern Hawaiian Islands, with the total population numbering about 75,000 breeding pairs. Smaller colonies are found on Kaʻula Rock and Lehua Islet off of Niʻihau, and islets off the eastern coast of Oʻahu. However, the colony on Lehua Islet appears to have been extirpated due to predation by rats. 

Although the Brown Noddy does not breed on Kauaʻi, it is seen regularly from shore or just offshore with flocks of Black Noddies or following flocks of birds over schools of tuna. It is much easier to see from shore in eastern Oʻahu. The colonies in Hawaiʻi are most active from May to October, with fewer birds present from November to April when most birds are at sea. Brown Noddies disperse widely across the Pacific, but tend to stay close to islands, and usually less than 100km offshore. At sea, Brown Noddies tend to fly in small loose groups, often low to the water. They only occasionally land on the water, but can often be found floating on oceanic debris. 

Like Black Noddy, Great Frigatebird, and the two booby species, Brown Noddies typically build their nests on small bushes or other vegetation, and have thus benefited from the introduction of non-native vegetation to the Northwestern Hawaiian Islands. However, populations in the Southeastern Hawaiian Islands were likely much larger in pre-Polynesian times and were probably wiped out due to predation by humans and non-native mammals. 

The identification of the two noddies from other species is fairly straightforward, with their medium to small size and all dark plumage. Initial confusion is possible with some small dark tubenoses such as Christmas Shearwater and Bulwer’s Petrel, but flight style is completely different, with noddies having a steady, straight flight with steady wing beats instead of the dynamic soaring typical of tubenoses. Brown Noddy can be separated from the very similar Black Noddy by the slightly larger size, brown body plumage with slightly contrasting black flight feathers on the wing, shorter and thicker bill, and the dark tail of the Brown Noddy. Black Noddies in the Northwestern Hawaiian Islands have dark tails, but those in the Southeastern Hawaiian Islands have contrasting pale gray tails.