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So as a biologist you are always interested in how animals are adapted to their environment
and Svalbard rock ptarmigans have extreme adaptations because they live in such an extreme
place high up in the Arctic.
It is light all day in summer and in winter it is about minus 20 and it is complete dark
and covered in snow. What they do is something very unique and something very special for
a bird. They actually double their body mass from summer to winter and this is something
we are interested in trying to understand how they cope by gaining this extra body mass.
If you think about putting a backpack on or carrying a heavy load you notice that it is
very hard work, if you are bringing some shopping or something, it's a lot of energy to do this.
So if you have got a natural animal model that can gain body mass yet still function
efficiently, this is what we are primarily interested in studying.
The way we are able to study this is that we actually train these birds to run on a
treadmill so we have them running inside a clear Perspex box and by analyzing the air
in the box when the bird is running at different speeds and when the birds are thin in summer
and fat in winter, we are then able to calculate the amount of energy that these birds use
to run and live around these different conditions.
The two things we have found about these birds so far are that they are extremely efficient
at moving around and, especially in summer, when they actually switch to running around
they actually experience a drop in energy costs so ptarmigans extremely efficiently
and this probably relates to the males having to run around, chase after females during
the mating season.
The other interesting adaptation we have seen in these birds is that in winter when their
body mass has doubled and they are very fat they stop running around. They prefer to walk
or to ground run but they are also able to experience an energy saving in doing this
as well so they also have adaptations for efficient moving in winter when they are very
fat.
Ptarmigan have the same gates that we see in humans so at slow speeds they walk and
at high speeds they aerial run. The different between the two gates is that during aerial
running you have your feet off the ground and as you travel through the air and your
foot hits the ground again for the next stride the tendons in your legs operate like springs
so you can imagine there is a spring just like a pogo stick in your leg.
The spring is compressed as your body weight falls onto that leg and as you launch again
for the next step that spring springs you forward and you continue running. The different
between birds and humans is the birds have a bird gate between walking and running which
is called grounded running and this gate shows characteristics of both walking and aerial
running.
In the ptarmigan what we found was that we get the drop in energy expenditure with walking
speed and then the line flattens out, the energy expenditure flattens out, and continues
flatly all the way through grounded running and then when the bird switches to aerial
running we get another drop in the energy expenditure. So we can see that the benefit
for switching from grounded running to aerial running - you are saving energy.
So what we have got with the Svalbard rock ptarmigan is that we have got a natural animal
model that is able to survive and cope extremely well in an extreme environment with large
fluctuations in body mass so what we are hoping is that the results that we have been able
to get from this study are going to have strong implications for understanding things like
how to improve animal welfare and the welfare of broiler chickens in particular.