(Posted by Andrew D. Smith <[log in to unmask]> via moumn.org)
Please know before reading further that this message is intended to be
educational, and is specifically NOT intended to be critical or pejorative of any
observer/person. My apologies as well for its length.
I was surprised to see earlier today on the MOU website, that the Least Terns
being observed in Rock County are now considered as "confirmed" breeders.
This has also been included on the "Occurrence Maps" on the MOU website,
prior to the birds even being voted on (and accepted) by MOURC. Wow.
The nature of this observation brought to mind similar circumstances of an
observation by Karl Bardon, of an adult and juvenile Least Tern in Dakota
County on 29 August 1992, as detailed in his informative article in THE LOON,
v.64 #4. Note the date as being somewhat close to the present observation in
Rock County. Therein he provides the following information: ..."The possibility
that these Least Terns nested in the vicinity is considered. The observation of
an adult bird feeding a juvenile may infer local breeding in some species (i.e.
most passerines), but in many tern species, including Least Terns, the adults
are known to occasionally accompany and continue feeding juveniles on
migration (THE WILSON BULLETIN 71:313-322)." Kenn Kaufman notes in LIVES
OF NORTH AMERICAN BIRDS, that juvenile Least Terns accompany adults for
2-3 months after hatching. Well into migration timing.
Bardon continues with his very critical look at both birds' molt status, (which
I'm uncertain has been attempted with the Rock Cty birds due to the distance
involved) and concludes: ... "The adult Least Tern and this dependent juvenile
could therefore have flown a considerable distance from the actual place of
nesting." The same may be true of these birds as well.
While I have been selective with the material quoted here, interested persons
are encouraged to read the entire article. Karl is one of the most respected
and knowledgeable birders in the State, and the article is an excellent read.
My intention here is to urge caution before jumping to conclusions. Perhaps
there is additional information about this claim of "confirmed " breeding that is
unknown to me. If so, please share it with us all. I would love to be proven
wrong. Otherwise I suspect that claiming this as a new breeding species for
Minnesota is more likely circumstantial or conjecture than fact.
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