The Potawatomi Zoo announced two red panda cubs were born on June 17.
The cubs were born to 7-year-old Maiya and 9-year-old Justin.
Within 24 hours, zoo staff weighed the cubs and determined one was smaller than the other and appeared to have respiratory difficulty. It was removed from its mother to be hand-reared by animal care staff.
Once the smaller cub has gained weight, staff will try to reintroduce the smaller cub to Maiya.
Within the last three weeks, the red pandas have both gained weight and appear to be thriving.
However, zoo staff are concerned because there is a high mortality rate for red panda cubs.
Red pandas are born with their eyes and ears closed, but they open within three weeks.
They are born with gray, wooly hair, but their reddish guard hairs start to appear after 2 weeks.