New snake lost 10g in 5 days

[Bogertophis]

Sounds to me like she expelled some waste (urates, fecal or both) someplace in her home. But you're right to keep an eye on things. She needs some "TLC" now.

I think that was too soon after arrival to be offering her food- too soon to expect her to eat it, anyway. What works for her brother may not work at all for her.

Her activity suggests she is stressed and still settling in- as you should expect. While it's very reassuring when a new snake eats for you, & all of us can "hardly wait" for that to happen, you need to be patient- a new home is extremely confusing for a snake & some take longer than others.

You didn't mention handling her, so I hope you know that's not what you should be doing until after she's feeding regularly (at least 3 times at normal intervals without refusals).

How you offer prey to a snake, and when, are both very important. BPs are nocturnal ambush predators, not active hunters, so they're more likely to eat after dark (in a quiet room with dim lights) when they're peeking out of a hide, and NOT when they're active in the enclosure. Remember that in the wild, when they're busy swallowing a meal, they're defenseless from predators who want THEM for a meal- those that have survived have instincts to avoid making the mistake of eating out in the open, & they're far too slow for "active pursuit".

They wait to ambush prey that gets close enough to where they're hiding: they recognize that prey by their body heat, so did you warm the f/t prey right before offering it? Many find that warming it quickly with a blow-dryer (AFTER it's thawed & right before offering from tongs) will elicit a strike from the snake, & then hopefully they'll go on to gulp it down if they're undisturbed by your presence- so hold very still- try not to let your startle-reflex drop the tongs when the snake strikes, & wait quietly for the snake to finish swallowing before you even close the cage- the vibration & any movement from you can make them drop the f/t & lose interest- & don't resume activity or brighter lights in the room until the snake has eaten. OK?

If the snake does refuse or drops it after a strike, it's fine to try leaving it overnight to see if they'll eat it anyway, later. Some will, but many won't. It may help to cover their enclosure to reduce outside distractions.

Just one thing to keep in mind: I know that most of you here love to weigh your snakes to know for sure what's going on, BUT keep in mind that weighing counts as "handling" that snake. It's something I NEVER do with a new snake that's not eating. It's okay to weigh a new arrival right when you have to handle them anyway to look them over, but after that, avoid doing so until they're eating regularly for you. Weighing is "handling".