EPOW - Ecology Picture of the Week

Click on images for larger versions

Weka in the Henhouse: A Lesson on Assisted Reintroduction

Credit & Copyright:  Dr. Bruce G. Marcot
  

Explanation:  This bird in the hand ... is a large flightless rail.  More specifically, a weka, found only in New Zealand.   More specifically still ... this bird has an interesting story to tell about extinctions and assisted reintroductions of wildlife. As humans continue to impact wildlife and their habitats, there is a growing need to conduct translocations of species, to reintroduce them to areas where they have become extirpated.  Sometimes this is called assisted colonization.   Wekas -- of species Gallirallus australis -- occur in New Zealand, historically with four recognized subspecies.  One subspecies is the buff weka, Gallirallus australis hectori, that had become exterminated from its natural range in eastern South Island of New Zealand.    Before extermination, however, in the early 1900s buff wekas were translocated to remote Chatham Island that sits in the South Pacific Ocean some 500 miles east of the main islands of New Zealand.  There, the buff wekas prospered, even supplying the local people with a limited harvest level and are eaten.   Buff wekas now occur only on Chatham Island (where I took these photos) and adjacent Pitt Island.   So buff wekas are an "introduced species" there.  Should they also be considered an "invasive species" as well?  They're not native to either Chatham or Pitt Island.   And Chatham Island is part of New Zealand, so this potentially "invasive, introduced" species was not transported across international line ...  This is truly an odd case of a subspecies, extirpated within, but successfully translocated outside and adjacent to, its native range.        Weka in the henhouse!  (Literally, it's inside a henhouse here.) The buff weka lives on ... outside its native range ... despite it being hunted, eaten, and surviving in an environment unlike where it evolved. The Tropical Convergence Zone bends the north of Chatham Island, putting the island proper in the sub-Antarctic climatic zone.  So buff wekas have been introduced to an entirely different climate realm!   Information:      Gill, B.J. 1999. The kiwi and other flightless birds. David Bateman Limited, Auckland, New Zealand. Acknowledgment:      My thanks to New Zealand wildlife biologist Frances Schmechel for having hosted us on the wonderful wind-swept plains of Chatham Island ... and for catching this week's subject!  That is Frances holding the bird in this week's main photo up top.  (Notice the piece of grass in its beak -- the weka's, not Frances'.  I tried to quickly grab it away for a better photo, but the bird spooked and ... spat a jet of poop directly onto poor Frances.  Sorry 'bout that, Frances!)