The bird, one of 23 first-year penguins fitted with satellite tags by University of Otago researchers, fledged from south of Owaka on February 19, and had covered more than 950km when it disappeared around Marlborough on Sunday.
Zoology PhD candidate Mel Young, who is leading the marine tracking study, said she was ''quite relieved'' after Takaraha appeared back online.
''I couldn't believe it,'' she said.
From Thursday night when it was near Blenheim to Sunday morning, the juvenile was foraging east of Cape Campbell.
There were several reasons a bird's satellite tag might not send its location: the bird could have been ashore under cover, could have pulled the device off, not enough satellites were overhead to get a transmission, ''or nature has taken its course''.
With the final two birds in the study fledging yesterday from Penguin Place, all 23 birds were in the water, the majority foraging off the coast between Oamaru and Timaru; but four transmitters were now offline.
And because only 20% of juvenile yellow-eyed penguins survive their first year it was ''a reality'' that not all birds would survive the study.
Takaraha's transmitter was paid for by the South Otago branch of Forest & Bird and branch chairman Roy Johnstone said yesterday branch members had been worried.
There were not only natural hazards, but ''fishing hazards'' along the South Island's east coast.
The study was ''absolutely critical'' to understand the area the birds used.
