Q: Is it true that birds will sit on a wire to keep their feet warm?
Thanks,
Avian Fowl
A: Dear H5N1:
In answer to your question we went to Rocky Mountain Power company:
100HB: "I was hoping you could tell me why birds sit on your powerlines. It has been suggested that it keeps their feet warm. Is this true?"
RckPW: "I don't know. I've never heard of that. I guess if it is a hot day and the sun is keeping the wire hot. It is metal...I really don't know. I can tell you why they don't get electrocuted though."
100HB: "No, that is alright, just want to know about why they sit up there."
RckPW: "I think it is becuas they can see prey from up there."
100HB: "As apposed to the wood sections of your poles? I mean why the wire?"
RckPW: "I don't know. But they don't get electrocuted because..."
100HB: "Yes, yes, I know the second wire bit. I just need to know about why the wire."
RckPW: "Beats me."
Oh, I think we will beat you...I think we will.
I went and asked one of our professors in Natural Sciences- he wasn't too pleased with the question. He started going off on how a bird will lift one leg close to its body to keep it warm and how wires provide unabstructed views for hunting.
Wow, you're a REAL professor and everything? So impressive (sarcasm).
The wires contribute no heat themselves to the birds' feet. First we are talking about high power transition lines and not telephone wires. With telephone and cable wires they are insulated so you wouldn't get any heat if it let out any at all. Just feel your cable to your lamp or cable box. Is it hot? of course not.
Now high power transmission lines I read average about 7.2% loss across them, which means somewhere the lines are resisting and changing the electricity into heat. This is due to grounding and the corona effect - a blueish discharge of electricity more than just heat loss in resistence. But b/c aluminum alloys are used in transmission lines it is possible to have some heat. Heat loss to resistence is given by Q = I^2 x R (power loss = current ^2 times resistence) Resistence in aluminum is 0.248*10^-8, average current in line is 100-3000amps (high voltage means low current PV=I (power x voltage = current). This gives about .00558kW in power loss. Power x Time = Energy - so assume you lost ALL of that energy is lost to one bird foot in a second. That's 5.58 kWs or 5.58 Joules. 1 Joule can heat 1 gram of dry air 1 degree Celsius. You release 1 Joule in 1 hundredth of a second. 1 /100th of energy in one drop of beer. So it COULD heat up a bird's foot a very little bit, but I assumed all the heat came out in 1 second at one point. No the bird ain't getting warm.
The real answer most likely has to do with wires warmed in the sun over the day that have a heat from radiation effect. Like sitting on a warm sidewalk. MUCH MUCH more effect from that (magnitudes more). Add in a social, hunting, and need to sit down and raise a foot to keep warm - and you have a handy community perch.
Until the Disney researchers get back with me, the answer is for the birds:
http://www.youtube.com/watch?v=s3IpOFsKcDQ
Thanks,
Avian Fowl
A: Dear H5N1:
In answer to your question we went to Rocky Mountain Power company:
100HB: "I was hoping you could tell me why birds sit on your powerlines. It has been suggested that it keeps their feet warm. Is this true?"
RckPW: "I don't know. I've never heard of that. I guess if it is a hot day and the sun is keeping the wire hot. It is metal...I really don't know. I can tell you why they don't get electrocuted though."
100HB: "No, that is alright, just want to know about why they sit up there."
RckPW: "I think it is becuas they can see prey from up there."
100HB: "As apposed to the wood sections of your poles? I mean why the wire?"
RckPW: "I don't know. But they don't get electrocuted because..."
100HB: "Yes, yes, I know the second wire bit. I just need to know about why the wire."
RckPW: "Beats me."
Oh, I think we will beat you...I think we will.
I went and asked one of our professors in Natural Sciences- he wasn't too pleased with the question. He started going off on how a bird will lift one leg close to its body to keep it warm and how wires provide unabstructed views for hunting.
Wow, you're a REAL professor and everything? So impressive (sarcasm).
The wires contribute no heat themselves to the birds' feet. First we are talking about high power transition lines and not telephone wires. With telephone and cable wires they are insulated so you wouldn't get any heat if it let out any at all. Just feel your cable to your lamp or cable box. Is it hot? of course not.
Now high power transmission lines I read average about 7.2% loss across them, which means somewhere the lines are resisting and changing the electricity into heat. This is due to grounding and the corona effect - a blueish discharge of electricity more than just heat loss in resistence. But b/c aluminum alloys are used in transmission lines it is possible to have some heat. Heat loss to resistence is given by Q = I^2 x R (power loss = current ^2 times resistence) Resistence in aluminum is 0.248*10^-8, average current in line is 100-3000amps (high voltage means low current PV=I (power x voltage = current). This gives about .00558kW in power loss. Power x Time = Energy - so assume you lost ALL of that energy is lost to one bird foot in a second. That's 5.58 kWs or 5.58 Joules. 1 Joule can heat 1 gram of dry air 1 degree Celsius. You release 1 Joule in 1 hundredth of a second. 1 /100th of energy in one drop of beer. So it COULD heat up a bird's foot a very little bit, but I assumed all the heat came out in 1 second at one point. No the bird ain't getting warm.
The real answer most likely has to do with wires warmed in the sun over the day that have a heat from radiation effect. Like sitting on a warm sidewalk. MUCH MUCH more effect from that (magnitudes more). Add in a social, hunting, and need to sit down and raise a foot to keep warm - and you have a handy community perch.
Until the Disney researchers get back with me, the answer is for the birds:
http://www.youtube.com/watch?v=s3IpOFsKcDQ
2 comments:
Thanks for the info. Always wondered. Also thanks for the good laugh at the end. Needed it. I guess my own life might be for the birds...I laughed a long time.
you have been busy 100 board, and i will add to your work load... i have a birthday coming up and this got me wondering, what month has the most birthdays celebrated in? thank you wise one...
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