Muttonbird, mutton-bird or mutton bird refer to seabird

Seabird

Seabirds are birds that have adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations...

s – particularly certain large shearwater

Shearwater

Shearwaters are medium-sized long-winged seabirds. There are more than 30 species of shearwaters, a few larger ones in the genus Calonectris and many smaller species in the genus Puffinus...

s – whose young are collected for food and other uses before they fledge

Fledge

Fledge is the stage in a young bird's life when the feathers and wing muscles are sufficiently developed for flight. It also describes the act of a chick's parents raising it to a fully grown state...

 (see also Muttonbirding

Muttonbirding

Muttonbirding is a seasonal harvesting activity, which may be recreational or commercial, of the chicks of petrels, especially shearwater species, for food, oil and feathers...

).

The species

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...

 most frequently called "muttonbirds" are:

• Short-tailed Shearwater
  Short-tailed Shearwater
  The Short-tailed Shearwater or Slender-billed Shearwater , also called Yolla or Moonbird, and commonly known as the muttonbird in Australia, is the most abundant seabird species in Australian waters, and is one of the few Australian native birds in which the chicks are commercially harvested...
  
  , nesting in south-eastern Australia, particularly in the Furneaux Group of islands in eastern Bass Strait
  Bass Strait
  Bass Strait is a sea strait separating Tasmania from the south of the Australian mainland, specifically the state of Victoria.-Extent:The International Hydrographic Organization defines the limits of the Bass Strait as follows:...
  
  .
• Sooty Shearwater
  Sooty Shearwater
  The Sooty Shearwater is a medium-large shearwater in the seabird family Procellariidae. In New Zealand it is also known by its Māori name tītī and as "muttonbird", like its relatives the Wedge-tailed Shearwater and the Australian Short-tailed Shearwater The Sooty Shearwater (Puffinus griseus) is...
  
  , nesting mainly in New Zealand
  New Zealand
  New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
  
   and islands in the South Atlantic Ocean
  Atlantic Ocean
  The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
  
  
• Wedge-tailed Shearwater
  Wedge-tailed Shearwater
  The Wedge-tailed Shearwater, Puffinus pacificus is a medium-large shearwater in the seabird family Procellariidae. It is one of the shearwater species that is sometimes referred to as a Muttonbird, like the Sooty Shearwater of New Zealand and the Short-tailed Shearwater of Australia...
  
  , nesting throughout the tropical and subtropical parts of the Indian
  Indian Ocean
  The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
  
   and Pacific Ocean
  Pacific Ocean
  The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
  
  s

There are several islands where "muttonbirds" breed and are harvested:

• Mutton Bird Island
  Mutton Bird Island
  Mutton Bird Island is an irregularly shaped island, with an area of 44 ha, in south-eastern Australia. Its highest point is 40 m asl. It is part of the Mutton Bird Island Group, lying close to the southern end of the south-western coast of Tasmania. It is also part of the Southwest National...
  
  , Tasmania, Australia
  • South East Mutton Bird Islet
    South East Mutton Bird Islet
    South East Mutton Bird Islet is a steep islet, with an area of 0.52 ha, in south-eastern Australia. Its highest point is 22 m asl. It is part of the Mutton Bird Island Group, lying close to the southern end of the south-western coast of Tasmania. It is also part of the Southwest National Park,...
    
    
  • South West Mutton Bird Islet
    South West Mutton Bird Islet
    South West Mutton Bird Islet is a dome-shaped islet, with an area of 0.52 ha, in south-eastern Australia. Its highest point is 28 m asl. It is part of the Mutton Bird Island Group, lying close to the southern end of the south-western coast of Tasmania. It is also part of the Southwest National...
    
    
• Broughton Island
  Broughton Island, New South Wales
  Broughton Island is an island north east of Port Stephens, New South Wales, Australia. It was seen by James Cook commanding HM Bark Endeavour on 11 May 1770: he mistook it for a headland and called it Black Head. After its insularity was discovered, it was re-named Broughton Islands, and so appears...
  
  , NSW, Australia
• Titi/Muttonbird Islands
  Titi/Muttonbird Islands
  The Tītī or Muttonbird Islands are located near Stewart Island/Rakiura in the far south of New Zealand.There are three chains, all of them simply referred to as the Muttonbird or Tītī islands. The northeastern chain is located in Foveaux Strait, to the northeast of Stewart Island, between it and...
  
  , New Zealand

Other uses of the term are:

• The Mutton Birds
  The Mutton Birds
  The Mutton Birds was a band from New Zealand formed in 1991 by Don McGlashan, Ross Burge, and David Long.-History:All three members came into the band with experience: McGlashan came from Blam Blam Blam and The Front Lawn, guitarist Long had played in the Six Volts and Burge had played in the...
  
  , band from New Zealand
  • The Mutton Birds (album)
    The Mutton Birds (album)
    The Mutton Birds is the eponymous debut album of The Mutton Birds. It was a huge hit in their native New Zealand, remaining on the charts there for over a year.-Track listing:#"Dominion Road" – 3.55...
    
    

In local Maori dialect, the bird is known as the "tītī" (less commonly spelled "tiitii")