Q54. One bird weighing 7 g departs Pelee Island, Ontario travelling southwest at an average rate of 43 km per hour on September 13th experiencing an average westerly cross wind of 10 km per hour. A second bird weighing 11 g departs East Fork State Park on September 17th travelling due west for 134 km at an average rate of 21km per hour with an average headwind of 6 km per hour before turning south and continuing at the same rate, experiencing the same 10 km per hour westerly crosswind as bird number 1. Assuming that daily foraging time for each bird is inversely proportional to mass divided by average daily energy expenditure and each mile travelled requires 4122 calories.
On what day will each bird arrive in Nashville?
There are several approaches to solve this problem:
Start with
the right-hand-rule,
given
I = S cos Z
where Z =
cos^-1(sin 36.1658º
sin [{23.4º*2
/(365.242/2)
*266}+{11.5[23.4º*2
/(365.242/2)]+-
23.4º}]+cos 36.1658
cos [{23.4º*2
/(365.242/2)
*266}+{11.5[23.4º*2/(365.242/2)]+-23.4º}]cos 15º(Time-12)
and the ever slanting
dance of light filtered
through the understory;
the lingering chill
in the dew
,and the lightning bugs
snuffed out like
candles;
a subtle twist in the
seat of the soul
and the
irresistible
call of
Zugunruhe
Or,
the heuristic approach:
watch the 12-day forecast
read the bird listservs daily
note the field marks
and check Sibley repeatedly
Or, for extra credit
integrate the obliquity,
eccentricity
and
precessional terms
Thuban drifts and winks over Gizeh
ice swells in the valleys
and pours down across the continents
blitzkrieg by the millimeter-per-year
the little refugee camps
adrift among the
Nunataks
playing the
Hardy Weinberg game
to pass the time
and the continent itself creaking out
and aft and up
like fingernails
(everyone is always saying)
and even before that
the ripple through the Flora Family
the Devil's Tick
like a thumbprint pressed into wet clay
and later South America creeping up
to kiss the scar
down where the bugs never disappear
and the leaves never turn
and anyway all of these approaches converging
on the same results
these
little
drab
olive and yellow
birds
falling
from the sky
and into our garden
on the crisp, unseasonably cool days
around the autumnal equinox
of 2012
and it's almost enough to make you think
the Mayan Long Count had it right
all along
