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Hi Dave et al,
This is perhaps splitting hairs because the Sandpiper (28g) and Blackpoll W=
arbler (European, probably ~10-11g) are both quite small birds and therefor=
e may be nearly equivalent, but any calculation needs to be framed in terms=
of what mass has to be kept aloft. It would take far more fuel consumption=
per hour to keep a heavy crow (450g) in the air compared to that for a sma=
ll light warbler, if they have similarly efficient lift-generating wings (d=
oubtful). It is usually framed in terms of body mass being proportional to=
the cube of the average linear dimension (LD^3), while lift generation is =
proportional to the square of the LD (LD^2) =97 so you need proportionally =
more wing lift area as the body mass increases until it finally becomes inf=
easible to fly at all =97 from memory the Great Bustard was reckoned to be =
the most massive bird that could still manage to fly.
I may have used this example before: biologist J.B.S. Haldane (an atheist) =
once penned a mischievous essay on the impossibility of the existence of an=
gels, at least in their depiction in medieval manuscripts, because to power=
wings that size (a big LD^2) would require a breastbone extending down to =
the ground to carry the enormous muscles required to flap them (humungous L=
D^3), not so illustrated in the manuscripts.
Albatrosses don=92t count much in this because an engineer C. Pennycuick (s=
p?) in the 1960s calculated that one species he looked at mostly used the u=
pdraft from wave crests to glide along on a sinuous path using lift energy =
derived from that, somewhat analogous to the larger scale thermals used by =
some migrating raptors and storks.
Understanding flight is complicated.
Steve (Hfx)
On Jan 24, 2015, at 3:33 PM, David & Alison Webster <dwebster@glinx.com<mai=
lto:dwebster@glinx.com>> wrote:
Hi Angus & All, Jan 24, 2015
In an e-mail of Jan 7, 2002 I estimated maximum flight duration based o=
n energy content of tallow and with initial conditions of 3 g total weight =
of which 2 g is tallow to be 126 hours (what I call weight would usually no=
w be called mass). In scanning this quickly I noticed two typos but whether=
these introduced error I don't know.
At that time Richard dug out an example which showed this simple model =
to considerably underestimate actual endurance--
START OF PASTE\\\\\\\\\\\\\\\
Hi Richard, Elizabeth & All, Jan 9, 2002
<SNIP>
> -- "A typical Blackpoll Warbler at the end of its
> breeding season weighs about 11 grams, equivalent to the weight of 4
> pennies. In preparing for its transatlantic trek, it may accumulate enoug=
h
> fat reserves to increase its body weight to 21 grams. Given an in-flight =
fat
> consumption rate of 0.6% of its body weight per hour, the bird then has
> enough added fuel for approximately 90 hours of flight for a journey whic=
h,
> under fair conditions, requires about 80 to 90 hours.
This Warbler beats my upper limit, perhaps by being a good weather
forecaster and using rising air currents.
My k equates to a loss of 0.87% of body weight per hour compared to 0.6=
%
loss in the Warbler. And when I plug 21 and 11 grams into my model, I get 7=
4
hours of flight compared to 90 hours for the Warbler.
Yours truly, Dave Webster, Kentville
END OT PASTE\\\\\\\\\\\\\\\
And the link below, for the Semipalmated Warbler, has 6 days of non-sto=
p flight over water (~144 hours).
The Albatross beats all of the above of course by staying aloft for yea=
rs without beating a wing. Holding wings out and tilting them and tail as r=
equired takes energy but still it manages amazingly efficient flight.
Yt, Dave Webster, Kentville
----- Original Message -----
From: Angus MacLean<mailto:cold_mac@hotmail.com>
To: naturens<mailto:naturens@chebucto.ns.ca>
Sent: Saturday, January 24, 2015 9:34 AM
Subject: RE: [NatureNS] Semipalmated Sandpiper migratory route
Can't imagine how thin that little guy was when it arrived at the Orinoco D=
elta!!
Thanks, Eric.
Angus
________________________________
From: E.Mills@Dal.Ca<mailto:E.Mills@Dal.Ca>
To: naturens@chebucto.ns.ca<mailto:naturens@chebucto.ns.ca>
CC: davidmary3@eastlink.ca<mailto:davidmary3@eastlink.ca>
Subject: [NatureNS] Semipalmated Sandpiper migratory route
Date: Sat, 24 Jan 2015 01:31:03 +0000
Courtesy of BCVIBirds, here is a fascinating link about the migratory paths=
of Semipalmated Sandpipers that stage in James Bay: http://goo.gl/at0GMZ
I suspect that geolocators have been used with east coast migrants as well,=
but I don't have that information.
Eric
Eric L. Mills
Lower Rose Bay
Lunenburg Co., NS
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Hi Dave et al,
<div>This is perhaps splitting hairs because the Sandpiper (28g) and Blackp=
oll Warbler (European, probably ~10-11g) are both quite small birds and the=
refore may be nearly equivalent, but any calculation needs to be framed in =
terms of what mass has to be kept
aloft. It would take far more fuel consumption per hour to keep a heavy cr=
ow (450g) in the air compared to that for a small light warbler, if they ha=
ve similarly efficient lift-generating wings (doubtful). It is usuall=
y framed in terms of body mass being
proportional to the cube of the average linear dimension (LD^3), while lif=
t generation is proportional to the square of the LD (LD^2) =97 so you need=
proportionally more wing lift area as the body mass increases until it fin=
ally becomes infeasible to fly at
all =97 from memory the Great Bustard was reckoned to be the most massive =
bird that could still manage to fly. </div>
<div>I may have used this example before: biologist J.B.S. Haldane (an athe=
ist) once penned a mischievous essay on the impossibility of the existence =
of angels, at least in their depiction in medieval manuscripts, because to =
power wings that size (a big LD^2)
would require a breastbone extending down to the ground to carry the enorm=
ous mu