Happy Feet could be lost forever.
The transmitter attached to the wayward emperor penguin before his release at the start of the month 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 transmission 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.
The company was still hoping to be pleasantly surprised and for the transmit to start working again.
"But if we don't get further readings then we'll have to hope for the best."