Use feeding tongs to feed snakes, it works much better than using hands..especially once you switch them over to frozen thawed (which is good ideal to do, especially with ball pythons which can be rather finicky, so best to get them on frozen thawed as soon as possible, or at least fresh killed)
Holding a frozen thawed rodent with your fingers is asking to get bit. If the rodent isn't quite warm enough or has cooled between sink (where it was warmed up) and the cage, it can cool pretty quickly..SO, your snake is presented with something that smells like food and the hottest object it sees will be your hand, and it may strike your hand in mistake...instead of the cooler form of the rat below your fingers. Feeding tongs puts that much more distance between your fingers and the rodent.
All my ball python bites have been feeding responses because I was stupid and offering food with my hands. Or trying to pick up my snake after handing mice/rats and forgetting to wash my hands and arms first.
Young ball pythons can be nippy, its normal. Sometimes they are more nippy during their shed cycle. Most grow out of it. Some never do. But, like any living thing, there are always those that are more aggressive, more calm, more etc. than the average.
I never feed my snakes outside the cage....more work than its worth and I don't want them to associate coming out of the cage as meaning 'I am going to be fed' It is much easier for a snake to bite when its outside its cage and already in your arms...In their cage you can see how they come out of their hides if they are about to bite. Besides, I rarely take my snakes out of their cages during their prime hunting/activity time (ie evenings for most snakes) I take them out during the day or early evening but before dark. I find they are more calm (being asleep) and typically content to explore a bit. I don't keep them out long though, unless I am presenting them at a show or something. Even then I give them breaks after they have been out for awhile.
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PHLdyPayne