Dr. Jonathan Ballou :
Hmmm - lets see... pandas, tamarins, California condors, black-footed ferrets, - to name a few. No - not harder to work with pandas - we have a very good relationship with our Chinese colleagues and we work very closely with them. We had two Chinese colleagues come to the zoo this breeding season to help us.
What makes pandas challenging is that in China females are often mated with several males (well, usually mated with one male but then artificially inseminated with sperm from other males as well). So determining which male is actually the real father of the cubs is tricky. DNA analysis have to be done to figure that out.