Use the chart below for the monarch data, and look for similarities and differences between the 2 species. Don't let their small size fool you, because hummingbirds are BIG eaters. Maybe this explains why people rarely see hummers when they aren't eating. In order to gather enough nectar, hummingbirds must visit hundreds of flowers every day. And, just one day of cold temperatures or bad luck finding flowers can mean death.
Hummingbirds press the limits, and live their lives only a few hours from starvation.
Thus, hummingbirds have devised a fascinating way to conserve energy. During torpor, the tiny bird's body temperature can drop by 50 degrees, the heart rate slow from 500 beats per minute to fewer than 50, and breathing may even stop for a period of time. A hummingbird consumes as much as 50 times more energy when awake than when torpid. If you were to find a hummingbird in torpor, it would appear lifeless. While torpor has benefits, there are risks too.