The serval has a short tail that measures little more than a third of its head and body length. Tails are used for balance. Arboreal cats such as the clouded leopard have thick, long tails. The snow leopard needs superb balance on the steep 40 degree mountain slopes and it too has a very long, thick tail.
By contrast the serval is a much more a ground dweller feeding on small prey such as rodents in the long grass. The short, thin tail tells us that the serval has less of a need for a balancing aid.
The large ears are linked to the same behavior. The serval can stand tall – it is the wild cat with the longest legs compared to body size of all the wild cats. The height coupled with very large ear flaps allow the cat to detect small prey in tall grass. The serval is a specialist small-mammal catcher.
Even the serval’s small head and relatively weak jaws support this style of hunting.
The serval does occasionally kill larger prey such as hares and young antelope but over 90% of the serval’s diet consists of prey weighing less than 200 grams which is about 2% of the female serval’s body weight.
Servals kill prey by pouncing on the animal when detected by their keen sense of hearing. I think you’ll find that the precise location of prey is often assessed through the sense of hearing.
Servals have short tails and big ears for the same reason: they hunt small mammals in long grass on the ground. It’s a evolutionary, anatomical characteristic reflecting the cat’s hunting behavior.
See: Serval description for more