[mou] Black Rail search image

[Robert_Russell@fws.gov]

As one of Minnesota and the Midwest's rarest and least known species, I
thought an article published back in 1999 in the Journal of Field
Ornithology (Vol 70, no. 4, pp. 465-480) (authors Larry Spear, Scott
Terrill, Colleen Lenihan, and Penelope Delevoryas) might have some
relevance to Midwest birders trying to locate this mythical creature.  I
say "might " because the article concerns the California subspecies, but
there is enough interesting data that some hints for finding Black Rails
might be applicable to the Midwest population.   Black Rails have been
reported very rarely as far north as the Twin Cities and rumored as far
north as St. Cloud so anyone in the southern half of the state ought to be
aware of its possible presence.  Researchers found detection probability
was relatively stable between late April and early June, but increased from
mid-June to early July, probably because of the appearance of
young-of-the-year.  Detection probability was greatest and variation least
from sunrise to about 1.5 hours thereafter, and likewise for the 1.5 hour
period preceding sunset.  Detections declined abruptly 0.75 hours after
sunset and were similarly low during the 1.5 hour period before sunrise.
Detections decreased with an increase in cloud cover and increased with an
increase in air temperature and moonlight (during the preceding night).
Much of the previous search image of at least eastern birds was based on a
couple of old articles in Birding based on the birds at Elliot Island,
Maryland where they seemed to like to call on full moon nights in May after
10 p.m.  This article shows that another search image might be also
productive.
Bob Russell, US Fish and Wildife Service, Ft. Snelling, MN