Around two in every five people who signed up to the Edinburgh Zoo scheme in 2013 chose to support Tian Tian or Yang Guang.
The UK's only giant pandas have been a major attraction since arriving at Edinburgh Zoo from China in December 2011.
There were hopes that Tian Tian was pregnant earlier this year but in October the zoo said she lost the cub in the late stage of pregnancy.
The pandas, however, are not the only animal selected by supporters of the scheme.
Penguins are also a popular choice for adopters with around one in 12 choosing a gentoo (8%) while around the same proportion chose a rockhopper penguin (7.5%).
Meerkats are in fourth place (7%) and koalas are fifth most popular (6.5%).
Adopters can choose from around 100 animals and receive a fact sheet about the creature, regular updates and an invitation to a special annual event.
At Highland Wildlife Park, the Scottish wildcat is most popular for adoptions, with the rate more than doubling in the last year to comprise a third of the total (34%).
While there are no official figures for how many wildcats are left in Scotland, some reports suggest as few as 35 individual animals are left in the wild.
A plan to halt the decline of the species was launched in September, involving organisations such as the Royal Zoological Society of Scotland (RZSS) which runs both visitor attractions.
The plan is designed to reverse the fall in numbers of the species, dubbed the Highland Tiger, within six years.
The Highland park's two polar bears, Walker and Arktos, are second most popular there (15%). Red pandas are third (10%) and the Amur tigers are fourth (8%). In fifth place is the European grey wolf (7.5%).
Fiona Skiffington, assistant membership and adoption manager for the RZSS, said: "Animal adoption is a great way to support the aims of the Royal Zoological Society of Scotland, a charity that receives no government funding.
"An adoption of one of our animals lasts all year and makes a fantastic gift. You can adopt online, by post or phone and prices start from £40 to adopt one of 100-plus species at either Edinburgh Zoo or the Highland Wildlife Park.
"Adopters get a personalised pack that includes a fact sheet on their adopted animal, regular updates and invitations to a special private yearly event and, depending on the level of adoption, their name at their adopted animal's enclosure.
"The money generated by our adoption scheme is put to good use. As little as £10 feeds a snow monkey for one week, £20 keeps the koalas toasty warm for one day, £25 buys a penguin nest ring for breeding season, £50 pays a conservation field assistant's wage in Brazil and £100 buys valuable education materials for our work in Scottish schools."