Good morning all,

I hope you can give me some hibernation advice please.  I have two Hermann's tortoises, both hatched August 2017, which I have had since August this year.  One of them was quite poorly when I got him (I am aware at two years old they are too young to sex, but I refer to them both as boys even though they may not be), but I nursed him back to health and I am pleased to say that as from mid September they were both eating really healthily and were very active.  

They lived outside in the outdoor enclosure connected to my greenhouse until the end of September when it became a little too cool, so I brought them both in to ensure they continued to eat well and fatten up before hibernation.

They are the same size with an SCL of 100mm, and the slightly heavier one weighs 208g (or at least he did at the start of the wind down process), and the slightly lighter one was 198g at the start of the wind down process, so both around 0.20 on the Jackson Ratio scale, so I considered it safe for them to hibernate.

I commenced the wind down procedure a few weeks ago, by stopping feeding completely and over the course of three weeks gradually reducing the length of time their Arcadia heat/UV bulb was on, and turning off any other background heating, whilst bathing them in tepid water every day to begin with, then less frequently as the three weeks elapsed.  Their indoor enclosure is in a spare bedroom, and I turned off the heating and had left the window open to ensure the room stayed nice and cool, and it got down to around 10 degrees in there during the last few days, because we had a rather nicely-timed cold spell. 

The last few days they both dug down into the substrate a little and they completely shut down, so after a couple of days I transferred them to their hibernation boxes, which were then placed in a larger box stuffed with shredded newspaper, and transferred the box to the shed.  They went into their boxes on 30th November.

Fortunately, the temperature during the last week has been ideal, with overnight lows of about 3 degrees C and day time highs of about 6/7 degrees, so right in a good range.  However, the forecast for the next few days is for much warmer weather, around 11 degrees today and up to about 14 degrees over the weekend.

I had prepareed for this eventuality by purchasing a small fridge which is also kept indoors to hibernate them in that on days when it was either too warm or too cold to be outside, but after monitoring the fridge temperatures for several days, I am concerned that the temperature fluctuates inside wildly, with lows of 0.1 degrees C and a high of 12.4 degrees C (and this in a fridge which supposedly has a temperature range of 2 degrees at its coldest and 8 degrees on its lowest setting!).  Given that the fridge is clearly unreliable I am at a loss what to do now, as I do not trust the fridge to keep a steady 5 degrees and am terrified of them freezing to death in there given the unreliable thermostat, but it is too warm for them outside at present, so I just don't know what to do.

If they wake up over the next few days is it safe to leave them until the temperatures drop off again, or am I better off just accepting that hibernation has failed this year, and to overwinter them indoors and resume feeding?  I would be grateful for any comments or advice.

I am also considering purchasing the Lucky Reptile Herp II incubator too, as this supposedly is able to maintain a steady 5 degrees and as it is ventilated means that in theory they can be safely left in this unit without needing to open the door periodically to allow sufficient airflow.  Does anyone have any experience of this or can recommend any other alternative fridge solution?

Many thanks, Richard