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State of torpor (1 Viewer)
- Thread starter galatea
- Start date
birdman
Орнитол&
Well, I googled "hummingbird torpor" and got this...
http://research.amnh.org/users/nyneve/hummingbirds.html
...which is worth a look not least for the groovy little hummingbird that follows the mouse pointer around!
http://research.amnh.org/users/nyneve/hummingbirds.html
...which is worth a look not least for the groovy little hummingbird that follows the mouse pointer around!
humminbird
Well-known member
galatea said:
My understanding is that it is a mechanism designed by nature to allow these birds to withstand periods of inclimant weather. People have described finding a bird and thinking it was dead - even to the point of boxing it up and preparing for a burial - only to have the bird "revive" and be successfully released. I recall one account where the person found the bird dormant on the feeder, touched it and the bird fell to the floor, picked it up, put it in a box and left the box on the kitchen table for a minute. When they looked over, the lid of the box was bouncing and their "dead" hummingbird was very much alive.
From what I understand, all metabolic processes are significantly lowered - pulse, respiration and of course, digestion. This allows the animal to survive with little or no energy intake. It is one area, among many, in these fascinating animals that I want to know more about!
Mark
gringorio
Member
torpor
When helping at a MAPS station in Arizona one summer we would often find hummingbirds in the mist nets. Many times they appeared to be dead--just hanging motionless in the nets, but after gingerly removing them and holding them in the flat palm of your hand they would 'wake up' and zoom off as if nothing had happened. I'm sure it was quite stressful for them though!
When helping at a MAPS station in Arizona one summer we would often find hummingbirds in the mist nets. Many times they appeared to be dead--just hanging motionless in the nets, but after gingerly removing them and holding them in the flat palm of your hand they would 'wake up' and zoom off as if nothing had happened. I'm sure it was quite stressful for them though!
humminbird
Well-known member
gringorio said:
I don't know if this would be caused by the same mechanism though gringorio. Torpor is certainly stressful, but I do not know that it could be initiated by a physical stress like that caused by a mist net encounter.
Mark
Bastrop, TX
Nutcracker
Stop Brexit!
gringorio said:
I suspect that is just 'playing dead' to confuse potential predators. Lots of birds do it when caught in mist nets.
After a short and far from complete literature research it seems to me that the definition of "torpor" is not clear. For some torpor means a body temperature at or only slightly above ambient temperature, others difine torpor reached with body temperature between 26-36 degrees centigrade, but that of course should be seen in respect to the normal body temperature of the regarding species and is probably higher for hummingbirds with a normal body temperature (Tb) of 40 degrees centigrade than for a bat with Tb at 32.2 degrees centigrade. Overall, torpor means that the normal body temperature is significantly dropped. However, it differs significantly from poikilothermy (body temperature is always close to ambient temperature, like in lizards), because no heat source from outside is necessary to end the state of torpor. The benefit is to save energy which is mainly achieved by to effects: first, the high energy costs to keep the high body temperature are decreased, and second, all processes are slower. "Life" basically consists of energy requiring chemical reactions in the cells (metabolism), catalyzed by enzymes which have optimal efficiency at normal body temperature. Lowering the temperature also decreases the speed of the chemical reactions, thus slowing down the whole metabolism, so that energy is conserved.
There seem to be basically two mechanisms to control torpor: first, the energy level of the animal. If the energy savings drop under a specific threshold, the animal enters the state of torpor. Second, a time-dependend mechanism, which is responsible for the wake-up. It can be "shallow" for a nightly torpor or seasonal for hibernation. There also seems to be a seasonal control in hummingbirds, since they enter torpor more easily e.g. during migration than during moulting.
I hope this was understandable and somewhat helpful. There still seems to be a lot of work to be done in the research of hummingbirds!
Marcella
There seem to be basically two mechanisms to control torpor: first, the energy level of the animal. If the energy savings drop under a specific threshold, the animal enters the state of torpor. Second, a time-dependend mechanism, which is responsible for the wake-up. It can be "shallow" for a nightly torpor or seasonal for hibernation. There also seems to be a seasonal control in hummingbirds, since they enter torpor more easily e.g. during migration than during moulting.
I hope this was understandable and somewhat helpful. There still seems to be a lot of work to be done in the research of hummingbirds!
Marcella
gringorio
Member
Thanks for the great reply Marcella... it seems like there's lots to consider. Maybe for the hummingbirds in the mist nets, torpor is a way to conserve energy when, at a certain point, the actual struggle to free themselves becomes detrimental (due to significant loss of energy) to their continued well-being (life)... ?
