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Mobirders, Linda Bobo asked some good questions, first on the list,
then a follow up off list.  I'm copying my response below for other
birders new to this whole wonderful arena of knowledge.

Edge Wade
Columbia, MO
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Hi Linda,

No, I'm not an ornithologist, just one who stumbled upon birding
about 15 yrs. ago and found the whole related topic fascinating.
I've read a lot on my own and, like you, have asked questions of
other birders.  Nearly every birder I have met has been a cheerful
teacher, eager to share bird lore.

If this is an immature, it hasn't taken this route before, but that
isn't necessarily a problem.  Cranes do usually migrate as a family
group, or at least within a loose flock.  Lone birds, though, are not
uncommon.  One is up in southeast Iowa right now.  These most likely
will eventually wend their way south and locate a flock, probably
along the gulf coast.  Those wonderful bugling calls are great help
to cranes looking for one another.

Most birds seem to be "hard wired" as to migratory route.  That is,
something is built in that gives direction/time to go/etc.  In some
species that nest in the arctic, the adults all leave before the
young are ready to fly.  Sounds counter survival of the species, but
the young are left to get the rich food supplies that the adults
would deplete if they stayed, and the young head south when they are
ready, following roughly the same route their parents took a month
before.

Sometimes a bird gets way off course--maybe because something is
wrong with its internal "gyro" or maybe because it got caught up in a
major storm front, or took up with a large group of a different
species.  These birds are probably in trouble in the long run.  Just
yesterday a Western Tanager that arrived in western Kansas with a
large flock of robins on Dec. 7 was found dead, unable to cope with
the weather and/or find enough of the right food.  The Black-throated
Sparrow in northwest Missouri right now was probably caught in a
storm and taken east.  It may survive the winter, but will find
nothing "homelike" when spring comes.  We'll probably never know if
it makes it back to others of its kind.

Sometimes a bird finds a migration route that (as far as we know)
hasn't been used by its species before.  An example is a Lazuli
Bunting that was seen the first week of May in northwest Missouri at
the same feeders for (I believe) 7 years in a row.  Off course, for
sure, but it found a route that worked for it and repeated it.  The
last year it was seen, there were more than one.  Perhaps this is how
new routes are established.  This, like mutation, can have many
failures but may develop into an expanded option for survival by
spreading the population out into new areas.  They may be marginal
under current conditions, but have the best survival opportunity for
the whole species under changed circumstances (habitat or climate
change, for example).

Another cause for birds out of range is chalked up to "post-breeding
dispersal."  These are most commonly sub-adult males [no, I'm not
anthropomorphizing about men asking for directions].  Perhaps it's a
mechanism for species expansion, as these may find a territory beyond
the main population to return to as an adult in the spring.  As with
mutation, again, there are far more failures than successes with this
phenomenon, too.  Examples of post-dispersal out of range birds
include a lot of wader species (ibis, spoonbills, herons); way out of
range Fork-tailed Flycatchers like the one we had in Missouri this
year; and possibly the Long-billed Murrelet, normally a pelagic (sea)
bird that is erratically found in big reservoirs in the midwest in
late autumn/winter.

That was a long answer to a short question.  But, you get the idea of
how fascinating I've found birds to be.


On Dec 25, 2009, at 3:31 PM, Linda Bobo wrote:

> True. Has it already flown the route? If not, how will it know?
>
> A very grim story. Are you an ornithologist?
>
> I have been seriously birding only a few yrs, so forgive some of my naive 
> questions that you are
> patiently answering.
>
>
> Linda
------------------------
Posted for Edge Wade by:
Susan Hazelwood
MOBirds-L Co-Owner
Columbia, Boone County, MO
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