Ruby-throated Hummingbird

For such a small bird, Ruby-throated Hummingbirds have a lot of attitude, and are known to chase all manner of birds much larger than they are – including raptors. But most of their ire is directed toward other hummers – or perhaps the occasional pollinating butterfly or bee – and late summer is the perfect time to observe these little aerialists in all their pugnacious glory. Young have usually fledged by late July, resulting in a noticeable increase in numbers at feeders and gardens. When more than one hummingbird has located a good nectar source there’s likely to be a turf war of some kind, as more dominant individuals repeatedly chase others away from “their” feeder. You might think there’s plenty of nectar to go around, but hummingbirds didn’t evolve in a world where flowers had a seemingly-infinite supply like feeders do. As a result, they’re doing what they’d do in “natural” conditions and defend a reliable source of food like their lives depend on it.​

Which may very well be the case. Hummingbirds have extremely high metabolic rates and need to feed almost constantly to fuel their active flying lifestyles. If a human scaled their diet to that of a hummingbird they’d need to consume over 150,000 calories a day – that’s roughly 600 average energy bars. A day. Don’t try this at home. At night, when they can’t forage, hummingbirds often go into torpor: lowering their body temperature so less heat is lost to the cooler evening air. Hummingbird physiology can be even more impressive during migration, when these tiny birds (they weigh the same as a penny) build up fat reserves – sometimes almost doubling their weight – to fuel sustained flight. This is enough for them to fly over the Gulf of Mexico, although most probably take the long route around to reach their Central American wintering areas. ​

Contrary to popular belief, keeping feeders out does not prevent hummingbirds from leaving in the fall. Our birds ​are mostly gone by the end of September (with males leaving before females and immatures), and unless there’s ​something wrong with them they’re not going to stick around.