Red kangaroo has the ability to freeze the development of an embryo until the previous joey is able to leave the pouch. This is known as diapause, and will occur in times of drought and in areas with poor food sources. The composition of the milk produced by the mother varies according to the needs of the joey. In addition, red kangaroo mothers may "have up to three generations of offspring simultaneously; a young-at-foot suckling from an elongated teat, a young in the pouch attached to a second teat and a blastula in arrested development in the uterus". The kangaroo has also
Nelson's kangaroo rat that litters consist of two young. Nelson's kangaroo rat has a wide range in central Mexico where it is generally uncommon, being present at an estimated density of 9–20 individuals per hectare. The total population is presumed to be large and it faces no particular threats so the International Union for Conservation of Nature (IUCN) has listed it as being of "least concern". Nelson's kangaroo rat Nelson's kangaroo rat ("Dipodomys nelsoni") is a species of rodent in the family Heteromyidae which is endemic to the central plateau of Mexico. Nelson's kangaroo rat reaches a length of about including a tail