Anous stolidus is a large bird, identified by its overall sooty brown plumage. Its size ranges from 36 to 45 cm. The wings are darker in colour and rounded in shape while the tail is wedge-shaped with a small notch at the end. Adult individuals have white eyebrows and foreheads. Male and female individuals are similar in appearance. Juveniles have plumage that is usually paler in colour. Their eyes are yellow and semi rimmed with white and their legs, feet and bill are black. Anous stolidus can often be heard making a hoarse ‘kark’ call.
The Common noddy is also referred as the Brown noddy and is usually confused with the Lesser noddy (Anous tenuirostris). However, the Common noddy is larger in size, has a heavier bill with a thicker base, compared to that of the Lesser noddy. It is also paler in colour, with paler underwings and the grey plumage on its crown does not extend beyond the nape area. It is also mistaken for the juvenile Sooty tern but can be distinguished by its pale forehead, crown and dark instead of white vent.
Anous stolidus is a tropical species and can be found all year round. They are absent from sub-tropical regions during certain seasons. They have a variable diet consisting of squid, small fish, insects, small molluscs and even medusa. Their main foraging sites are coastal lagoons, but they may fly out to the open ocean.
The breeding period usually varies according to the species’ range and may occur in large groups or solitarily, depending on the availability of nesting sites. A single egg is laid. In the case of Mauritius, the Common noddy breeds only on Serpent Island, nesting mainly during October and November. As part of the mating ritual, noddy birds nod at each other.
The Common noddy is of ‘Least Concern’ according the IUCN listing as it is present over a wide range across the globe and population sizes are stable. Major known threats are predation from rats, cats and the brown tree snake, Boiga irregularis.
It is the largest of the noddies.
It has often been observed that Brown noddies steal food from pelicans or catch any remains that fall off their bill.