 Hummingbirds spend an average of 10–15% of their time feeding and 75–80% sitting and digesting.Because their high metabolism makes them vulnerable to starvation, hummingbirds are highly attuned to food sources.Some species, including many found in North America, are territorial and will try to guard food sources (such as a feeder) against other hummingbirds, attempting to ensure a future food supply for itself.