Domestic cats much prefer mice to birds no matter what source of information you refer to (including personal obesrvations by the cat owning public). In order to assess what, at a fundamental level, domestic cats prefer as prey animals you have to go back to their wild ancestor which is the African-Asian wildcat, otherwise knows as the North African wildcat.
Dr Desmond Morris writes in Cat World that in order to understand the diet of domestic cats it helps to look at the natural food of their wild relatives. The African wildcat (Felis sylvestris libyca) has a similar diet to its European counterpart but with various kinds of African mice making up 70% of their diet. Birds are a “minority interest” at 10 to 20% and only slightly more popular than reptiles at 10 to 13%.
The definitive book on the wild cat species, Wild Cats of the World states that the diet of the African-Asian wildcat is primarily unidentified voles (at 42.9% of prey in scats in south-east Kazakhstan). Gerbils of various species make up 40% of its prey. Pheasants and other birds amount to around 18%. I have not itemised the other prey animals because I’m emphasising the fact that birds are not a priority prey animal for the domestic cat’s wild ancestor.
Below I have provided a spreadsheet showing the breakdown of prey animals for the domestic cat’s ancestor; the figures of which come from a third source as stated. Once again the point is emphasised. Domestic cats prefer mice or small mammals such as gerbils and voles over birds.
Translated into domestic terms it means that the ideal diet for the domestic cat would be canned role or mouse with a little bit of roughage and an added vegetable supplement (the stomach contents of the small mammals it eats).
It should be noted, therefore, that the public profile or perception of the domestic cat as preferring to attack and kill birds in their billions across the planet is misplaced and unjustified. Although this perception has been going on for centuries.