Migration etc.
Canada Goose, Pelicans and Monarch Butterfly
Geese:
From the vantage point
of our residence on Crescent Lake we can observe the spring arrival of geese on their migration north. We have always watched with interest and amusement
the raising of families of geese – usually one or two families per season each consisting of two parents
and usually 4 to 6 goslings.
The view of migrating Canada geese from our porch in Portage la Prairie, Manitoba |
As
summer comes along they become more organized into groups as they move around
the lake training to “follow the leader” in straight and evenly spaced lines in
preparation for their fall migration south.
This spring we observed a pair of geese with
more than twenty goslings, some of which were obviously hatched prior to
others. This is referred to in the literature as, “adoption, creche or mixed brood, gang-brooding and
kidnapping” which isn’t very helpful in knowing how this feat is accomplished.
The probable answer is in the susceptibility of goslings (and other birds and
even animals) to filial imprinting (from the German for "stamping in") during the first few hours after hatching. The
parents wanting a lager family need only be the closest moving large object at
the right time and the young goslings will follow them as their
"imprint" parents. I imagine this could happen accidentally as a pair
of geese swims past groups of goslings at the opportune time and have them
added them to their family as they go by.A pair of geese and their expanded family |
Imprinting
was popularized in the movie Fly Away Home (1996), based on
the actual experiences of Bill Lishman,
who in 1986 started training geese to follow his ultra light plane
and succeeded in leading their migration in 1993.
Research fostered around imprinting has led
to related learning about the importance of very early experiences
in the development of the brains and activities of animals in a wide range of
activities affecting them throughout their lives, even to the “negative imprinting”
in human siblings (raised together for at least 6 years) that makes sexual activity between them unthinkable for them. Pelicans:
Most years we think it is a major event to see a few pelicans on Crescent Lake for a day or two in the summer. This year we have observed as many as 58 pelicans on the lake (actually an ox bow of the Assiniboine River) at one time.
They
staying day after day to feed in a group frenzy (presumably on the little fish accidentally pumped
into the lake from the Assiniboine River). We have no idea why the sudden
increase in their numbers here.
Pelican flight coming in |
Pelicans feeding as a group |
Monarch Butterflies:
In
spite of a worrisome decrease
in 2010 in the Mexico population of Monarch butterflies, there has been a
breathtaking increase in the general butterfly population
in western Canada in 2012.
Their migration between Mexico and other countries is complicated
by the fact that although the species migrates north and south every
year (like birds) their life cycle dictates that no one individual completes the entire journey which is
spread over a number of generations, The ones that return to
overwinter in central Mexico are at least great-grandchildren of the one who
had left that same 60 square miles
but have never been there before themselves .
The following diagram from Parks Canada
may be helpful, but if it is still confusing take comfort in knowing you are
not alone. The transfer of route information through the generations is unusual
to say the least.
Monarch Butterfly migration to overwinter |
Life Cycle of Monarch Butterfly |
The End
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