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Why Birds Don’t Get Cold Feet

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Re: Why Birds Don’t Get Cold Feet

#11

Post by climb_stealth »

serf wrote: post #10
dukeofdoom wrote: post #9

Earlier quoted context omitted.

I know the behaviour you are describing, but the pigeon had its foot severed at the ankle. I saw the actual leg, so its not that it was hiding it. Looked more like pirate stub.

Ah , that's too bad. This article mentions a correlation between pollution and loss-of-limbs in urban pigeons. They even mention it may due to human hair entanglement from hair salons as a primary culprit -- that seems far fetched to me, but who knows.[0] I tend to think that it's mostly just environmental entanglement, pigeons are pretty curious animals. [0]: https://www.birdspot.co.uk/bird-brain/why-do-so-many-urba…

I always wonder whether it is the spikes that are used to deter birds from sitting on ledges. At least that's what comes to my mind whenever I see birds with mutilated feet. :/

Re: Why Birds Don’t Get Cold Feet

#13

Post by randoramax »

dukeofdoom wrote: post #4

I was sleeping on a balcony in Hawaii on a trip, when I woke up there was a one legged pigeon that was hanging out right next to me. Ever since then I noticed quite a few birds with a missing foot. Makes me wonder how much sensitivity birds have in their feet.

Attacks from cats and rats, most likely.

Re: Why Birds Don’t Get Cold Feet

#14

Post by throwawayboise »

umvi wrote: post #12
pfdietz wrote: post #7

Countercurrent exchange is a remarkable thing that every engineer should know about.

Can you list some examples of where this is used in engineering (software or otherwise)?

A fresh air exchanger in an HVAC system. The fresh external air coming in is [warmed|cooled] by the interior air being exhausted.

Re: Why Birds Don’t Get Cold Feet

#15

Post by thaumasiotes »

serf wrote: post #6
dukeofdoom wrote: post #4

I was sleeping on a balcony in Hawaii on a trip, when I woke up there was a one legged pigeon that was hanging out right next to me. Ever since then I noticed quite a few birds with a missing foot. Makes me wonder how much sensitivity birds have in their feet.

Looks can sometimes be deceiving with regards to one-legged birds. My pet goose (yeah, weird pet, but she was from an egg I saved and incubated) does a trick where when she sleeps she puts her head under under a wing and lifts a leg up -- she sleeps on a single leg with her head tucked like a big ball of balanced feathers with tremendous balance and grace. She tucks her leg up so high into her down fluff that you can…

> My pet goose (yeah, weird pet, but she was from an egg I saved and incubated)

Did you find the egg in the wild? I was under the impression commercial eggs were generally not fertilized.

On a different note, how does your goose behave toward people? My dad still tells stories of the cute easter chick he raised, which grew into a non-cute rooster that took over the back yard and terrorized everyone except my grandmother.

Re: Why Birds Don’t Get Cold Feet

#16

Post by pfdietz »

umvi wrote: post #12
pfdietz wrote: post #7

Countercurrent exchange is a remarkable thing that every engineer should know about.

Can you list some examples of where this is used in engineering (software or otherwise)?

Open hearth steel mills. Regenerators in some gas turbines. Dialysis machines. Liquid-liquid extraction. Isotope separation cascades. Fractional distillation columns. Most heat exchangers are countercurrent, as it minimizes entropy generation.

Re: Why Birds Don’t Get Cold Feet

#17

Post by Retric »

umvi wrote: post #12
pfdietz wrote: post #7

Countercurrent exchange is a remarkable thing that every engineer should know about.

Can you list some examples of where this is used in engineering (software or otherwise)?

Milk pasteurization is one of the best examples.

You start with milk at 4C, heat it to ~70C via heat exchanger (+66C), then 75c via heating (+5C), wait 15 seconds for pasteurization, cool down to ~9C via heat exchanger (-66C), then just chill to 4C via refrigeration (-5C).

This requires ~1/14th the energy to heat the milk and also rapidly cools it down below ambient temperature afterwards saving even more energy.

You see similar approaches for a lot of large scale chemical processes.

Re: Why Birds Don’t Get Cold Feet

#18

Post by fy20 »

throwawayboise wrote: post #14
umvi wrote: post #12

Earlier quoted context omitted.

Can you list some examples of where this is used in engineering (software or otherwise)?

A fresh air exchanger in an HVAC system. The fresh external air coming in is [warmed|cooled] by the interior air being exhausted.

Also know as a heat recovery ventilator. If you are building a new house, read up on these, as you probably want one.

Re: Why Birds Don’t Get Cold Feet

#19

Post by DoreenMichele »

Retric wrote: post #2

This doesn’t explain why the interstitial fluids and cells themselves in a birds feet avoid freezing. Presumably, either their feet can simply be maintained at slightly above freezing or they use some form of antifreeze. Does anyone know?

The article says this:

It’s pretty much all tendons and bones. So, unlike your human foot, which contains plenty of moist muscle tissue, a bird’s foot contains only very little fluid in its cells.

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