[Tweeters] Torpor in Hummers

[Steve Hampton via Tweeters]

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 at u.washington.edu> 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 at u.washington.edu> 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 at u.washington.edu> 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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-- 
​Steve Hampton​
Port Townsend, WA  (qatáy)
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