These tiny birds may fly as many up to 1500 miles in just a few weeks from places as far as central
Argentina. Threats along the way
include the lure of windows and light up skyscrapers, natural predators like hawks as well
as domestic predators like house cats. Weather also plays a huge
factor in the life or death of these birds. A spring storm or cold snap,
excessive heat or a head wind can be the difference in success and failure. It will come as no surprise that a head wind is the most prevalent
weather obstacle. For anyone who has ever tried to run, bike, even walk into the wind you will know it is harder and more
energy is used than when moving with the
wind. During the spring birds will use a southerly tail wind (wind blowing
from south to the north) to aid in this long journey. When the wind is
coming from the north “northerly wind” birds will often reroute or wait for a
change in wind direction.
England a north or northwesterly wind occurs when a high pressure
system pushes a low pressure system out to sea. High pressure systems are not
only the large “H’s” on the weather map they are also associated with cool, dry
weather on the ground, and cloudless, clear blue skies and sunshine above –
the archetypal “nice day.” April
showers bring May flowers and spring as a whole is often a drizzly month.
Days of off and on spitting light rain coat the flowers and tree buds. This
type of warm, humid air is typical of a low pressure accompanied by a south
wind – good migration conditions. What we've seen this spring ( April into early May 2013) is a stationary high pressure
sitting just west of New England. This steady
high pressure has meant clear skies, no rain, and a near consistent northeast
wind – terrible conditions for migrants. So let's pray for some humid air, light drizzle and a breeze from the south and on it will come the birds!