All that glitters is not necessarily gold, as keepers at the African Plains section of Dublin zoo have learned.
For months they have been trying to discover if one of its female white rhinoceros, Ashanti, is pregnant or if her companion, Zanta, is fertile.
The only way to determine the hormone levels in either animal is to review their excreted waste twice a week over a three-month period.
This presented the zookeepers with a problem. They could not tell one rhino's waste from the other - until they had a bright idea.
They added different coloured glitter - silver for Ashanti, blue for Zanta - to their feeds.
The glitter is non-toxic and has proved to be both simple and safe.
The zoo is hopeful the results, due in the new year, will show that Ashanti is pregnant.
White rhinos, which are actually grey, are very difficult to breed in captivity and it is 14 years since a baby was born at the zoo. Unfortunately, that rhino, Dorothy, was shot after she tried to escape while being loaded on to a trailer.
While the zoo keepers are hopeful Ashanti is pregnant, everything to do with a rhino pregnancy is laborious.
Attempts to get the dominant male rhino, Sam, to mate with Ashanti were unsuccessful when Sam proved literally not up to the task - despite receiving industrial-strength levels of Viagra from vets at the zoo.
Ashanti was mated with the younger male, Chaka, in January, after a short courtship.
As there is no rhino equivalent of the human pregnancy test kit there will be a period of suspense before the test results are returned.
A rhino's gestation period is 16 months, the longest term after the elephant and the whale in the animal kingdom, so the calf should be born in April, assuming that Ashanti is pregnant.
Helen Clarke, team leader of the zoo's African Plains section, said they "can't wait" for the results.
"We assume that she's pregnant because she hasn't come into season since last January, but we'd like to check for sure.
"We were struggling until we had this idea and are so pleased that it seems to be working. It's an ideal way of getting good samples without separating the rhinos, or worse still, following them around all day with a shovel."
