Would you believe the biggest killer of birds in the United States -- 1.3 billion feathered friends per year -- are cats? If you have a pet cat and can't keep it inside, be sure to add a bell to its collar. Since cats have the ability to stalk their prey and pounce, a small bell can make just enough noise to give warning to the birds (and other small animals) that they're in harm's way. You can find other collars designed to prevent cats from harming birds, but a simple bell works just fine.

If your car is parked and idling for more than 10 seconds, turn it off. Even though you're not driving at highway speeds, a car that's on but not moving is still using one-quarter to one-half a gallon of gasoline per hour. In the colder winter months, if you want to warm up your car, it's recommended you do it for no more than 30 seconds total. With new models, that's not even necessary; it's driving that actually warms up the engine, not simply turning it on.

A timeless tip but a good one: Always bring reusable bags to the grocery store. According to EarthShare, if you grocery shop once a week, in five years' time, you'll have prevented anywhere from 250 to 1,000 grocery bags from getting into the landfills. But why only bring reusable bags to the grocery store? Use them at the hardware store, when you shop for clothes or at any store where you can opt out of using a bag. And if you forget, ask if the store can put your items in a cardboard box -- there are usually lots in the back -- and put it in the recycling bin as soon as you get home.