Guests come to your zoo to see your animals and are attracted to different animals for different reasons.
The source of this attraction is the animal's Appeal and is based on a number of factors:
Species Appeal
Some species are just more interesting and therefore appealing to guests than others and will have a high Appeal score.
Genetic Quality
Within a given species, animals with the strongest genetics tend to be the most appealing to guests. When looking at the animal exchange, look out for the shiny medals; these indicate the animal's genetic strength.
Not only will animals with great genetics have a tendency to produce strong offspring, they are also likely to be larger and healthier than other animals, therefore improving their appeal.
Star Rating
If an animal is well looked after and therefore has excellent welfare, its star rating improves over time. The larger the rating, the higher the appeal If the rating reaches five stars, the animal becomes extremely attractive to guests.