I have been seeing hundreds of robins during the last few weeks, both in
Montgomery County and on the Eastern Shore in Kent County. That got me
thinking. Years ago I heard an intriguing discussion about robin
migration. There were two theories offered:
> 1. Southward shift - This postulated that robins we see in the winter
were
> birds that bred to the north, say Nova Scotia or Newfoundland, while
"our"
> summer birds went further south to Florida. In this theory all Eastern
> Seaboard birds simply move several hundred miles to the south of where
they lived
> in the summer.
>
> 2. Leapfrog - This theory suggested that "our" summer birds stayed at
> roughly this latitude, although moved to appropriate areas where there
were lots
> of berries for winter sustenance. The northern birds leapfrogged in
> migration over "our" robin population to winter to the south.
>
Does anyone know whether either of these theories has been proven by
banding returns or other research?
Bob and all,
This is the sort of question that should be answered on line so it can
be shared. I have long propagated the southward shift theory. If I've been
wrong all these years, I would like to be corrected.
Jerry Tarbell
Carroll County |