Hi rc_3. Hopefully you’re getting your rosy directly from the breeder. They can advise you on exactly how the snake is being kept currently, and you can use that info to help the transition be smooth. If you’re buying from a flipper of some sort, they won’t have as comprehensive advice. I have about 15 breeding rosies, and have produced and sold quite a few neonates, but it is still useful to try to make conditions the same as what your particular snake was used to from birth.
Presumably you’re using a glass fish tank, and while that’s fine some rosies don’t seem to appreciate the ‘open’ feeling. So as caron mentioned, a good selection of hides and such is a good idea.
While rosies (like pretty much all snakes) will dig down into many substrates, they’re not adapted to fossorial behavior and so this is an artifact of captivity. Making the snake dig to the glass to find its preferred temp isn’t ideal (though as mentioned above, the thermostat probe goes between the glass and the heat mat – the probe temp is not necessarily the same as the target temp at the place the snake will be). If you provide a couple hides on the warm end, and see to it that those hides hit 90 or a little more inside the hide, that’s good.
But since the temp at the glass will be higher than that target temp if you use only a heat mat in a glass enclosure, the halogen lamp can be useful in conjuction with the mat (run the halogen only during daylight hours, of course). And depending on how the ambient temp in the enclosure settles out, the halogen lamp can make more of the enclosure be at a decent warm temp instead of having one hide be 90F and the rest of the enclosure 70F. Gentle gradients make for more useful space than hot or cool and nothing in between.
Ideally, a thermostat would run the lamp as well (a thermostat should be considered necessary for the heat mat), but this isn’t always practical. You can adjust the intensity of that lamp with a plug-in dimmer switch.
While cold temps won’t likely kill rosies outright, inadequate temps definitely will cause a failure to feed. Captive care and wild conditions are not the same, and not only because animals have adaptive behaviors to compensate for wild conditions that they cannot necessarily engage in in the confines of a 10 gallon tank.
I’m going to disagree on the advice to only offer water periodically. While very high humidity is of course best avoided, if a water bowl causes that much RH increase then the enclosure is inadequately ventilated. Keeping the bowl small and on the cool side will reduce evaporation, but the idea that rosies need things bone dry is often overstated. Withholding the ability of an animal to drink when it “wants” to should be done only in specific and rare circumstances. Chronic low grade dehydration is a real issue in captive herps.
Keep in mind that there are two species of rosy boa, and a couple distinctions within those species, so what works for someone’s adult coastal rosy is not necessarily going to be great for a neonate “Mexican” locale. In general, L. orcutti – especially “coastal” locales – are going to be much more bulletproof and unconcerned with housing details, and the non-peninsular L. trivirgata are going to be less so (high desert and baja locales tend to be somewhere in between)
