It is hard to find words to describe the mass descent of tens of thousands,
likely millions, of monarchs from their clusters. Flying downward does
not seem to do it, although that is clearly what they are doing. They
ride the air like a kite, but they descend. They float on the air, but
ride it downward. They stream in kind of a formation, always downward.
If you look upward, their flight appears chaotic with no apparent direction.
Nearer the ground they are always streaming downward. They land on moist
grass and stick their proboscises into the moisture.
downward movement shows clearly that the once stable winter clusters are
breaking up. Each week the colony is lower on the mountainside. This week
they were about 100 meters lower than the previous week, both at Chincua
and Rosario. Each day they descend and reform lower down. They are headed
home – home being the place where they breed.
There is much mating now. Small males drag their precious cargoes across
dusty trails towards a sunfleck. If successful, they accumulate enough
heat to warm their muscles so they can fly to a safe perch in the trees
above. Here the male will pass a spermatophore to the female and, if lucky,
the sperm will fertilize her eggs. But this is unlikely. A female will
mate many times because she needs the nitrogen from a number of spermatophores
to make egg yoke. (Note: Recent research shows that the last male to mate
with a female fertizes the eggs she will lay, so these early matings are
usually futile for the male.)
There is much cascading now, another sign of colony breakup. There is
hardly anything that dazzles more than the simultaneous falling of tens
of thousands of butterflies from a roost—as if gravity suddenly
pulled with extra force—then all fly off in the same direction before
reaching the ground.
But the most
constant behavior now, and the behavior that dazzles the most, is the
golden flow downward that gives the impression of a blizzard of butterflies
– an experience that one is likely never to forget.
our group includes the Bonnydale Environmental Education Center in Brattleboro
Vermont, a handful of Texans from the Dallas area, and a lone Wisconsinite.