The transmitter attached to Happy Feet before his release appears to have stopped transmitting.
The transmitter had been sending back tracking information which showed he had travelled south and then east of his drop off location at 51 degrees south.
Our Far South, the company helping to use the tracking data to come up with locations, has not received a transmit since September 9.
It was initially thought that solar flares could be disrupting the signal.
However, the company now believes the most likely scenario is that the transmitter has fallen off.
"After all it was only glued on and would have had to survive extreme conditions.
It will be at least a couple of days before we know for sure that the transmitter is no longer working."
Other possibilities included transmitter damage or technical failure.
We can think of at least one other possibility, which might or might not have something to do with a well-fed sea mammal having indigestion whilst trying to swallow electrical equipment.
Unfortunately, Happy Feet's return to the wild was always likely to end in tears; after all; he defied the odds in making it to New Zealand in the first place!
And in a remarkable piece of timing, the other Happy Feet had an adventure of his own this morning:
@angusbhodgson Angus Hodgson
Is this the end of the Happy Feet story?