- dropped or missing tail
- missing or stumpy arm/leg
Tail dropping is a natural defense mechanism in response to sudden loud noises, pinching, squeezing, or grabbing. In the wild it is used as a means to escape predators.
Limb loss is very rare, as mourning geckos rarely squabble to the point of inflicting serious injury — however, it can happen, especially if the injured individual is a younger member of the colony. It can also happen if a gecko gets pinched by the terrarium door/lid.
Mourning gecko tail loss is not a medical emergency, and there is no special care needed. The stump will eventually grow back, although the replacement will never look the same as the original.
Limb loss is also not a medical emergency. You may attempt to disinfect the wound or remove the gecko to a quarantine enclosure, but mourning geckos are often too small and fast for these measures to be practical. Make sure terrarium conditions are kept hygienic, and you may need to upgrade the colony to a larger enclosure to make sure the girls have enough space.