Birdseed: a universal foodstuff?

Most creatures are quite specialised in what they will eat, carving out a niche based upon a particular foodstuff in a particular habitat, becoming perfectly adapted via the evolutionary process. However, if the evidence from our garden is anything to go by, many animals will quite happily cast aside millennia of specialisation in order to gorge upon Haith’s Original Wildbird Food. As the name would suggest, this feast of seeds and grains has been concocted with wild birds in mind; small, busy birds like blue tits and robins and chaffinches. It was not, it is safe to say, designed for cats, deer and foxes.

Haith's Wildbird Food: manna from heaven?

Why then do these three in particular go crazy for it? Deer at least are herbivores, and so seed isn't too much of a stretch from their usual diet of leaves, twigs, fungi and the like; foxes are omnivorous, although most of their diet is made up of invertebrates; but domestic cats are carnivores through and through. Their bodies just aren't designed to deal with nuts and seeds. What is it then about birdseed that is just so good?

One possibility is that the cats are simply pretending to eat the seed, lurking around the vicinity of the feeder in the hopes of ensnaring an unwary bird. Or it could be that the seed, having often been kept in garages or warehouses where small rodents abound, smells irresistibly of mice. However, a lot of the time the cats do seem to be genuinely eating the seed, fully concentrated on gobbling it up and as such blissfully aware of what is going on around them. And I have heard tell that dogs will lap the stuff up also.

One factor that may well play a role is the huge amount of energy packed into the tiny seeds. For example, sunflower seeds provide a whopping 6.5 kilocalories per gram (compared to 5.0 kcal / g in custard creams and a measly 0.3 kcal / g in carrots). When it's cold outside and food is scarce, this is not to be sniffed at, providing one has a digestive system that allows it to be absorbed. The ruminant stomachs of deer will certainly be fine, and that of the fox will have a good bash, but cats? They simply don't have the right kind of teeth to even get started on the process.

Perhaps cats are simply not very bright. This is certainly the case for one of ours, and indeed it is she who seems to chomp down the birdseed most voraciously. Or perhaps they are simply economically savvy: after all, Haith’s sunflower seeds for birds cost around £2 per kilogram whereas those designed for human use from Julian Graves come to an astonishing £7 per kilogram. It would thus seem that people should start munching on the birdseed too!