Birds, feeders and the garden

My Dad loves feeding birds. He spends a lot of money every winter buying enormous bags of bird seed. And the birds love him, too. He has quite a few visiting his feeders for most of the year (he stops feeding them in May and starts up again in September). He loves to look after them, providing cover for them to hide in by planting bushes and native plants, and going out to shovel areas for the ground feeders if the weather is bad. It gives him a sense of purpose.

However.

Garter snakes- a gardener's best friend

Garter snakes are only mildly venomous, and even if they bite you they don't produce enough to harm a human. But they are very effective predators, eating slugs, insects, worms, frogs, minnows, and even rodents if the snake is large enough, all of which (except the worms, minnows and frogs) are generally bad for your garden. They have very distinctive markings- three yellow stripes run their length on a dark or black background. Garter snakes give birth to live young, unlike most reptiles. Adults can range in size from 45cm (18") to over a meter (over 45") at the very top end (but that would be a rare one, and probably wouldn't find enough food to stay in your back garden).