Brown Teal
Encyclopedia
The Brown Teal or New Zealand Teal, is a species
of dabbling duck of the genus Anas
. The Māori
name for it is Pāteke. It was considered to be conspecific with the flightless Auckland and Campbell Teals in Anas aucklandica; the name "Brown Teal" was applied to that entire taxon
. The Brown Teal has since been split, recognizing that the insular A. aucklandica and A. nesiotis are good species. In international use, the name Brown Teal is still more common than New Zealand Teal for this bird.
The Brown Teal is rather nocturnal in habit by dabbling duck standards. This seems to be an evolution
ary response to the fact that most predators on New Zealand, before humans arrived and brought with them carnivorous mammals, were diurnal birds such as Haast's Eagle
or skua
s.
It feeds by dabbling and upending, like its relatives. Its diet consists mainly of aquatic
invertebrate
s like insect
s and their larvae, or crustacean
s. It appears quite fond of mollusks. Small species such as pipi (Paphies australis
) and large wedge shell (Macomona liliana
) are eaten whole and crushed in the gizzard. For feeding on larger cockle
s such as Austrovenus stutchburyi
(New Zealand cockle), at least some New Zealand Teals have developed a peculiar technique, as of now undocumented in other birds, to force their rather soft bills between the cockle shells and tear out the flesh with a jackhammer
-like pumping motion. At night Brown Teal will forage on land some distance from the streams used as a refuge during the day (Worthy 2002).
This species is endangered and occurs only on offshore islands. Formerly, it was widespread on the New Zealand mainland, but it disappeared there due to introduced predators like cats, dogs and rats, which easily preyed on this unwary, weakly flying bird. According to the IUCN categorization as VU D1, fewer than 1000 adult birds remain. The species has recently been upgraded to endangered
by Birdlife International
(Birdlife 2007), and the change will be reflected in the next update of the IUCN red list.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of dabbling duck of the genus Anas
Anas
Anas is a genus of dabbling ducks. It includes mallards, wigeons, teals, pintails and shovelers in a number of subgenera. Some authorities prefer to elevate the subgenera to genus rank...
. The Māori
Maori language
Māori or te reo Māori , commonly te reo , is the language of the indigenous population of New Zealand, the Māori. It has the status of an official language in New Zealand...
name for it is Pāteke. It was considered to be conspecific with the flightless Auckland and Campbell Teals in Anas aucklandica; the name "Brown Teal" was applied to that entire taxon
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
. The Brown Teal has since been split, recognizing that the insular A. aucklandica and A. nesiotis are good species. In international use, the name Brown Teal is still more common than New Zealand Teal for this bird.
The Brown Teal is rather nocturnal in habit by dabbling duck standards. This seems to be an evolution
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
ary response to the fact that most predators on New Zealand, before humans arrived and brought with them carnivorous mammals, were diurnal birds such as Haast's Eagle
Haast's Eagle
Haast's Eagle was a species of massive eagles that once lived on the South Island of New Zealand. The species was the largest eagle known to have existed. Its prey consisted mainly of gigantic flightless birds that were unable to defend themselves from the striking force and speed of these eagles,...
or skua
Skua
The skuas are a group of seabirds with about seven species forming the family Stercorariidae and the genus Stercorarius. The three smaller skuas are called jaegers in North America....
s.
It feeds by dabbling and upending, like its relatives. Its diet consists mainly of aquatic
Aquatic animal
An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...
invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s like insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s and their larvae, or crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s. It appears quite fond of mollusks. Small species such as pipi (Paphies australis
Paphies australis
Paphies australis or pipi is a bivalve mollusc of the family Mesodesmatidae, endemic to New Zealand.The pipi is a shellfish with a solid white, elongated symmetrical shell with the apex at the middle. It is covered by a thin yellow periostracum...
) and large wedge shell (Macomona liliana
Macomona liliana
Macomona liliana, or the large wedge shell, is a bivalve mollusc of the family Tellinidae.-References:* Powell A. W. B., New Zealand Mollusca, William Collins Publishers Ltd, Auckland, New Zealand 1979 ISBN 0-00-216906-1...
) are eaten whole and crushed in the gizzard. For feeding on larger cockle
Cockle (bivalve)
Cockle is the common name for a group of small, edible, saltwater clams, marine bivalve molluscs in the family Cardiidae.Various species of cockles live in sandy sheltered beaches throughout the world....
s such as Austrovenus stutchburyi
Austrovenus stutchburyi
Austrovenus stutchburyi, common name the New Zealand cockle or New Zealand little neck clam, is an edible saltwater clam, a marine bivalve mollusc in the family Veneridae, the Venus clams.-References:* Powell A. W...
(New Zealand cockle), at least some New Zealand Teals have developed a peculiar technique, as of now undocumented in other birds, to force their rather soft bills between the cockle shells and tear out the flesh with a jackhammer
Jackhammer
A jackhammer is a pneumatic tool that combines a hammer directly with a chisel that was invented by Charles Brady King. Hand-held jackhammers are typically powered by compressed air, but some use electric motors. Larger jackhammers, such as rig mounted hammers used on construction machinery, are...
-like pumping motion. At night Brown Teal will forage on land some distance from the streams used as a refuge during the day (Worthy 2002).
This species is endangered and occurs only on offshore islands. Formerly, it was widespread on the New Zealand mainland, but it disappeared there due to introduced predators like cats, dogs and rats, which easily preyed on this unwary, weakly flying bird. According to the IUCN categorization as VU D1, fewer than 1000 adult birds remain. The species has recently been upgraded to endangered
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
by Birdlife International
BirdLife International
BirdLife International is a global Partnership of conservation organisations that strives to conserve birds, their habitats and global biodiversity, working with people towards sustainability in the use of natural resources...
(Birdlife 2007), and the change will be reflected in the next update of the IUCN red list.