An autopsy will be undertaken to find out what caused the death of an endangered Hector's dolphin found washed up on a beach in the Blueskin Bay estuary, north of Dunedin, over the weekend.
Department of Conservation marine ranger Jim Fyfe said he was alerted on Saturday by a resident who reported spotting its remains among the branches of a tree that had fallen into the estuary.
It was not there when he visited, but, after more phone calls, Mr Fyfe eventually found it washed up on a beach near the Mapoutahi Pa site yesterday and recovered it.
The body of the mature female showed no obvious signs pointing to a cause of death, but its remains would be sent to Massey University in Wellington for an autopsy, he said.
That was something that happened each time a dead Hector's dolphin washed ashore, because the population was so vulnerable, he said.
The discovery comes after dolphins were spotted in Otago Harbour last week, but Mr Fyfe said they were bottlenose dolphins and the dead Hector's dolphin was not part of the same pod.
Warrington resident Susan Wigmore told the Otago Daily Times she made the find while out walking dogs on Saturday morning.
''We were throwing sticks into the water for the dogs to fetch and we came across this poor little dolphin stuck in the branches.
''It was on its side, just on the water line. It was really sad to see.''
She feared the dolphin may have become trapped in the branches of pine trees that had fallen into the estuary channel after erosion in the area.
However, Mr Fyfe thought the body may have washed in and out of the tree branches sometime after its death.
''They [Hector's dolphins] echo-locate and they have a fairly good sense of space within the marine environment.''
The area was known to be home to about 40 of the about 7000 Hector's dolphins found only in New Zealand waters, he said.
Results of the autopsy were expected to take several weeks.