Do pouched mice alter litter size through resorption in response to resource availability?

The pouched mouse, Saccostomus campestris, an African cricetid rodent with a solitary lifestyle, shows a wide range of litter sizes (1-13), both in th e wild and in captivity. The occurrence of this species in areas ranging fr om dry semi-deserts to coastal dune forests as well as their unspecialised diet led us to suggest that it is a true opportunist. This is supported by their unique adaptation to respond swiftly to sudden environmental changes during pregnancy, by being able to resorb part or all of their foetuses as late as approximate to 72 hours prior to parturition. Partial resorptions m ay furthermore occur more than once during the same pregnancy. No correlati on between litter size and rainfall - an indicator of resource availability - was recorded, but litter size was more predictable in dry and wet enviro nments than in intermediate environments. Furthermore, pregnant females wer e recorded throughout the year. We suggest that pouched mice occupy and bre ed in a variety of environments. including unpredictable environments. by b eing able to breed throughout the year and adapt litter size through resorp tion of foetuses when environmental conditions are less favourable.