# fish tank + cold + baby nest = problem (?)



## Cereal Killer (Nov 23, 2014)

So, now it is basically winter and I don't use heating in my flat so this is pretty comparable to temperatures inside a shed. I am sure that the adult mice will cope with that in their fairly shielded fish tank in my wall cabinet, but I have observed the following with infant mice which I find concerning:

When the female mouse is pregnant, she will start building her nest. She rips off large pieces of cardboard and starts to build it as deep as she can. But here is the issue: after a couple of inches she hits the bottom of the tank because I only reasonably fill it with that much bedding and then she can't dig deeper. I believe that her instincts tell her that the hole has to be at minimum so and so deep, e.g. about half a foot to 1 foot deep. I have also observed that they try to 'extend' the height of the floor around the nest by digging the bedding around in the cage (opposed to just making a pile above it, they actually rather will raise the whole floor around). This leads me to believe that the depth of the nest actually has a much higher priority in the mouse's evolutionary program than other considerations, like heat insulation. The glass floor conducts heat very well. With plastic this would be less of an issue.

The last generation of mice I saw the same thing happening after the 8th day or so I checked and saw them on the bare floor. But it wasn't as cold as it is now and they all turned out fine and developed eventually even faster than normal. Now I checked from below the tank where I saw them seemingly trying to escape the cold of the glass floor (or maybe rather/also the light I shined through?) unsuccessfully. I think what happens is that they will shuffle the few sparsely layed cardboard scraps on the bottom away after a few days when they got older and expose themselves to the floor (and this is only possible because the glass is so extremely slick). The mother then cannot really undo that, or isn't even really aware of it. I touched it from below and it was very warm, as warm as my hand ... That implies that those 6 furless perfectly heat-conducting mouse children are busy with heating up a palm sized surface of a quarter inch thick glass up to body temperature below them (which is quite a lot to my perception). Also since yesterday I hear them making noises all the time, as if complaining.

What I now did was to tape a low powered sock heater (8W or so) below the tank at the blank spot. They are no longer making noises now, but I can't really tell if it is because of the heat. I hope it is not too much heat, but I wouldn't believe so since those heating pads are very weak and designed to work with 9V batteries ... also it takes quite a lot of energy to heat up that glass without having the heat dissipate into the entire surface of it.

I think this is an issue with glass tanks in general and the mother mouse can't help to build the nest wrong and escape any suggestions to nest differently. I would rather not want to disturb the nest and move them by hand somewhere else in the first days, not even first 2 weeks.

Perhaps there are other ways, like filling a cardboard box with bedding up to the top of the tank in one corner?

Do you have observed the same?


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## Cereal Killer (Nov 23, 2014)

Ok, so ... lession learned: *don't use heating pads even if it is just 3 watts or something!* Although I was checking and touching the pad after it ran 5 minutes and it wasn't warm at all it seems that it must have suddenly gotten more effective especially when not exposed to air under the tank ...

I checked and touched the glass and it was uncomfortably hot, in one small spot even so hot it would be painful. Luckily the mouse mother had reacted quickly to the temperature change and when I checked she had put about half an inch of toilet paper between the glass and the babies.

So .. the temperature must have been fine all along(?) and she would have changed the nest if it wasn't. And also I think I quite misjudged how well glass conducts heat. I think a little heating would still be good but I am not using those pads anymore. Just too dangerous. It is really strange how it could get that hot under there when the pads just feel a little warm to the touch in open space. The babies all seem to be fine.


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## Cereal Killer (Nov 23, 2014)

Now they started chirping again ... I recorded the calls they make:






I don't know if they just are more lucent now that it is colder ... or if they are complaining it is too cold. I only know this is new and proably a sign of discomfort rather than constant alarm that they are alive.


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## Cereal Killer (Nov 23, 2014)

So I added the heating pad again with tape from below but on half the power now and wrapped in aluminium foil tape so that it has triple the surface area and shouldn't create any hot spots. I could barely feel the heat when I left it under a different spot for 15 minutes or so. I hope that will help. I have read that pups will mostly call if they are cold and that makes the most sense to me. I only hope that the underpowered pad does anything at all. After all they can apparently shield against too much heat easily, but creating it is a whole lot more difficult. I am not so sure how intelligent the pups are individually to avoid being braindamaged by a powerful heating surface. So I don't want to do anything too much.


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## Ruth (Jul 3, 2014)

I really think you need to just leave them to it, they know what they are doing. If you must use a mat , and I wouldn't advise it, then make sure there is a gap for airflow to prevent over heating , between the mat and the tank. You can raise the tank using scraps of wood and then place the mat below, the airflow will dramatically reduce the chance of overheating.


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## SarahC (Oct 3, 2008)

it's very important not to disturb the nest in cold weather even to clean it.As long as the nest is intact they will be fine.


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