Date: 12/30/25 6:13 am From: Steve Hampton via Tweeters <tweeters...> Subject: Re: [Tweeters] Torpor in Hummers
One study showed Anna's go into torpor for only about 3-5 hrs per night, so
not the whole night. It takes them about 30 minutes to go in and out.
See Figure 2 at Spence and Tingley 2021.
Body size and environment influence both intraspecific and interspecific
variation in daily torpor use across hummingbirds
<https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/1365-2435.13782>For those new to the topic, or just waking up (!), when hummingbirds are in
torpor, their heart rate drops nearly 90%, from about 450 beats per minute
down to 50; their body temperature falls from 107°F to as low at 48°F; and
they seem to barely breathe. A hummingbird in torpor sits fluffed with its
eyes closed, looking nearly lifeless.
On Mon, Dec 29, 2025 at 11:33 PM Robert O'Brien via Tweeters <
<tweeters...> wrote:
> Wow, I had never heard of anyone else who had such an experience.THANKS.
> This was long ago and I do now have heated feeders.
> Maybe going out of torpor at or before dawn is normal, even when it is not
> so cold and even if there are not feeders available. In the wild, that
> is. And I have had these feeders at night in the cold with the porch light
> on. I wondered whether they would feed at night but didn't see it. But, I
> could easily have missed it.
> Bob
>
>
> On Mon, Dec 29, 2025 at 10:42 PM Louise via Tweeters <
> <tweeters...> wrote:
>
>> I had similar experiences to you, Bob. I would bring in my feeders at
>> night when it was cold enough to freeze them, then put them out at the
>> first hint of light, and I had hummers leap onto the feeder while it was
>> still in my hand, before I could even hang it.
>>
>> Someone here on tweeters (I forget who) told me that in winter, the
>> hummers will even wake from torpor and feed in the dark, so bringing the
>> feeders in at night can be detrimental to them. So I bought one of the
>> feeder heaters (one of the little lamp bulb versions that puts out just
>> enough heat to stop it from freezing) and I always leave them out. This is
>> the type I have - it just clips onto the bottom of the feeder. I only need
>> it for about one week a year on our area, but it was cheap enough.
>>
>> Louise
>>
>> On Mon, Dec 29, 2025 at 4:08 PM Robert O'Brien via Tweeters <
>> <tweeters...> wrote:
>>
>>> Over decades of birding I've experienced 'torpor' or 'not' twice. This
>>> seems an appropriate time to discuss them for possible feedback.
>>>
>>> 1. I had a hummer feeder on my front porch. When I went to refill the
>>> feeder I accidentally dropped and broke it. No backup. So I got an olive
>>> jar about 2"x 4"deep, filled it with 'the, 'juice' and fashioned a way to
>>> attach it. That worked fine. The male Rufous just landed on the edge and
>>> sipped away. I sorta forgot about it, but one day, when I returned home, I
>>> happened to glance at the jar and noticed an apparently dead male Rufous,
>>> bill down in the jar, now empty of juice.. I guess it had to dip further
>>> and further down, until it actually fell in. Oh, no. No idea how long it
>>> had been in there, but I knew about torpor, so I cupped it in my hand for
>>> warmth and went into the house. In 5-10 minutes I felt a 'stirring' 5 or
>>> so minutes later, I released it back outside, apparently none the worse for
>>> wear.. Great.
>>>
>>> But, conversely. Years ago, we had 3 or 4 nights here, SE of Portland,
>>> with a low of 6 degrees F. I had a bona fide feeder back on the porch that
>>> I took in during the night so it did not freeze. I got up each morning
>>> when it was just barely light to replace the feeder in case any hummers
>>> were surviving, which seemed unlikely. When I did this the first morning,
>>> a female Anna's immediately flew up from low weeds on the ground 15 feet
>>> away, and started partaking. This repeated the following two nights after
>>> which it warmed up.
>>> Now, this hummer was undoubtedly in Torpor (or not?) during the night,
>>> aided likely by some amount of ground heat to prevent freezing, even in
>>> Torpor. So,
>>> 2. How did the hummer know to spend the night on the ground?
>>> 3. How is it that the hummer was 'awake' at barely first light, as
>>> though waiting for me to replace the feeder. I don't think they can come
>>> out of torpor immediately, can they?
>>> And at 6 degrees I wasn't loitering on my porch, I put the feeder up and
>>> the hummer arrived immediately.
>>>
>>> Hmmmmmmmmmmmmmm? Bob OBrien Portland
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