There are some 36 species of shag worldwide. Twelve of these are found in New Zealand, of which eight are endemic (found nowhere else). In many countries, shags are called cormorants. The name shag is thought to refer to the shaggy crest some species have on their heads. Four species of shag are found at ZEALANDIA: the kawau pū (black shag), kāruhiruhi (pied shag), kawau tūī (little black shag) and kawau paka (little shag). These four species all belong to the genus Phalacrocorax, the black footed shags, which are found mainly in freshwater or coastal seawater.
Shags are swift underwater swimmers, with a sharp hooked beak to help them catch fish and small crustaceans. After a bout of fishing, shags must spend a lot of time perched with their wings spread out, preening and drying their feathers. This is because their feathers are not waterproof, making it easier for them to dive and stay underwater, but it also means the birds quickly get waterlogged and cold and must dry off afterwards.
The little shag has highly variable plumage, ranging from all black to pied (black and white). Adults have yellow facial skin and a small black crest on the forehead. Most little shags at ZEALANDIA are the white-throated phase (type) with white around the face and throat but black down the neck, breast and belly. Juveniles are mostly black and develop white plumage as adults. Juveniles and the adult all-black phase can be confused with the little black shag, but closer inspection reveals the difference. All little shags have short, stubby bills, yellow in adults, dark in juveniles while the little black shag has a long, slender lead-grey bill and dark facial skin. The little shag also has a noticeably longer tail than the little black shag.
Little shags began nesting at Zealandia in 2003. Numbers roosting at the sanctuary fluctuate seasonally with up to 70 birds counted during winter, and fewer than 10 in February when nesting is over and fledglings have become independent.