Jack Bowling wrote


You have just given a bang-on description of female American
Robins in basic plumage of the subspecies T. m. _propinquus_. I would
strongly doubt that Eye-browed Thrushes occur in flocks anywhere out of
there normal range. Perhaps there is occasional sex-segregated
migration in the species.


I am very interested in "sex-segreated migration". I will never forget
showing some slides of a trip to mexico where I photographed a Yellow-bellied
Sapsucker. I was surprised to see the sapsucker down there. Alan Baldridge of
Monterey casually mentioned that the female Yellow-bellied Sapsucker migrated
further south than did the male. I was amazed that he had this eclectic bit
of information which he casually tossed out, but I was also intrigued that
there would be such a mechanism. Why would sexes of the same species migrate
in different ways? How would that have evolved? What would be the advantages
of doing this? I can sort of understand why adults might migrate earlier
than juvenilles. There are strategies that make some sense. (Of course I
recognize the whole anthropomorphic realm of sense) But differences between
the sexes in matters of migration is most intriguing.


Jim Rosso
Issaquah
206-392-8440