Ask Sam: Why Do Hummingbirds Fight Each Other?
Every other Friday on Morning Edition NHPR’s Sam Evans-Brown tracks down answers to questions about the environment and outdoors for our listeners in a segment we call “Ask Sam."
Debbie Beauvair from Deerfield, N.H., asks: "I have a question about hummingbirds. We’ve noticed in the last 3 weeks or so that the number of hummingbirds have increased and the fights are off the charts. Our feeders are socially distanced by humminbird standards — at least 20 feet apart — but they’re swooping and chasing all over the place. What’s going on?"
Now, in a first ever, we’re actually going to do a two-fer, because relatedly, Sue in Bradford emailed to ask: “Do hummingbirds sleep and if so, where? I can't see any nests.”
And while it might not be obvious at first, I will show that these questions are indeed related.
So our hummingbird expert is Anusha Shankar who is doing a post-doc at the Cornell Lab of Ornithology.
"They always fight, that's what they do, that's how they exist," Shankar says.
She says the reason that our caller is seeing more hummingbirds is straightforward: fall migration has begun, and all of the ruby-throated hummingbirds — which is the only species that you’ll commonly see in the entire eastern United States — are headed south to Central America where they accordion in to a tiny overwintering ground all together.
And Shankar says they fight because they really, really, really need the food sources that they find.
"They don’t have much of an energy store as a backup if they dont’ feed all the time," she explains, "So they feed every 15 minutes sometimes, and they could die if they don’t feed for like two hours. They’re operating on a really, really thin edge … like a very tight energy budget."
Hummingbirds are just constantly burning calories. Shankar's research shows they spend as much as 80 percent of their days flying or hovering. And one hummingbird scientist calculated that if we wanted to do the equivalent work and consume the equivalent amount of sugar to power it relative to our body size, you’d have to drink a can of soda every minute to keep it up.
Now this gets us to the connection between the fighting question and the sleep question. They fight all the time because they need to eat all the time. They also need to sleep, which is tricky when you need to eat all the time, and every night, they sleep HARD. They enter a state called torpor.
"If you were actually torpid and I shook you, you wouldn’t be able to to do anything for it for 20 or 30 minutes, because so many functions in your body would be just switched off, and you wouldn’t be able to respond to outside stimuli," Shankar says.
During torpor, the heartbeat of the ruby throated hummingbird drops from 600 per minute to less than 50 per minute when they sleep. Worse than your teenagers.
And just to round out this 5 minutes of absolutely BANANAS hummingbird facts: hummingbird females do make nests. They are tiny, adorable little jobs which the females make by gathering SPIDERWEBS to hold together all the little nest bits. How about that?
Sam Evans-Brown, is host of NHPR’s Outside/In which you can subscribe to where-ever you get your podcasts. If you’d like to submit a question you can record it as a voice memo on your smartphone and send it to firstname.lastname@example.org, OR call the hotline, 1-844-GO-OTTER, OR submit it here.