The way jaguars fish may shed some light on why domestic cats mess around with water. Jaguars feed on a wide range of prey including fish. Turtles are an important part of their diet.
The jaguar’s fishing method has been discussed and it seems that there have been disputes over it. Indians sharing the jaguar habitat say:
“the jaguar goes a little way out into the water, and there discharges some saliva, which attracts the fish, which the jaguar flips out onto the banks with his paw…”
That doesn’t shed any light on why domestic cats tap and play with their water rather than drink it. It also begs the question why jaguar saliva attracts fish!
However, other versions state that the jaguar lures fish by tapping on the surface of the water with their tails. Voila! Doesn’t that sound familiar? Well not exactly but domestic cats tap or flick the water in their bowls with their paws. They also scoop water up in their paws. Jaguars scoop up fish once lured in. I think there is a sufficient similarity to be able to hypothesise that the origin of the domestic cat water tapping is in wild cat behaviour as demonstrated by the jaguar.
An interesting aspect of jaguar-water-tapping is that Indians say it imitates the sound of fruit falling into the water. This attracts fruit eating fish. Yes, believe it or not there are fruit eating fish and they are attracted to the sound of falling fruit.
Jaguars catch fish whenever possible. Like the tiger they eat whatever is available from anteaters to squirrels and rodents. They also eat a considerable amount of plant material. Plant material was in 21% of samples which is the same percentage as the most common jaguar prey: brocket and white tailed deer1.
Note: 1. Wild Cats of the World page 314.