The answer is fairly straightforward. They have big ears because most of their hunting takes place in long grass detecting small mammals with their ears. They can pick up the sound of prey travelling through the undergrowth with their highly sensitive ears and huge ocelli (ear flaps). The serval’s long legs go with their long ears because they provide a lot of leverage allowing them to jump high and descend hard on prey.
The serval’s diet normally consists of prey weighing less than 200 grams. This is about 2% of a female serval’s bodyweight. In Zimbabwe a mouse and a rat weighing up to 80 grams and 200 grams respectively make up the bulk of the serval’s diet. In Tanzania the vlei rat makes up most of the cat’s diet. Rodents appear in 90% of the faeces of servals in Tanzania.
Perhaps of all the wild cat species, the serval depends the most on small mammals like rats and mice which means that they have developed particular skills in detecting and killing rodents by pouncing on them, stunning them with a blow from one or both forepaws and then biting them behind the head.
They tend to swallow prey whole and on the spot. If they pluck a bird first and then eat it slowly. Snakes are pounced on and hit with fast blows from their paws or bitten repeatedly. In short, the serval has a particular “high pounce-and-strike and bite rodent killing technique” which as mentioned depends upon excellent hearing and long levers for limbs.
As for their shortish tail, we have to refer to the tail as a piece of anatomy which helps with balance. Servals spend most of their time on the ground hunting prey as mentioned and therefore do not need their tail for balance when climbing trees as other wild cat species sympatric to the serval often do, such as the leopard.
Servals are highly successful predators. In the Ngorongoro Crater in Tanzania a scientific study revealed that about half of their hunting/killing pounces resulted in a meal and each serval there captured between 5,700 prey animals per year which is equivalent to about 3,950 rodents, 260 snakes and 130 birds per serval per year. Impressive.