Thank-you, Maeve Kim.  Your approach seems very humane and gentle, and I 
greatly appreciate how you assisted the confused creature.  Agway would be 
an easier shop to manage such a rescue in, I would think, because it is so 
much smaller and has lower ceilings.  But I suppose the end result of just 
needing the bird to stop for a few moments down low enough for us ground 
dwellers to help remains the same.  

I also received a response from my wildlife biologist son, who says that this is 
a common problem at various large stores like Hannaford's, Home Depot, etc., 
where loading doors are open wide in the back.  In his view, birds who venture 
seem to always find their way back out.  "If one has been inside for several 
days it may be that a door that used to be open is now closed, or maybe it is 
going in and out on purpose. There are a lot of seeds/crumbs and such in the 
produce/bakery section to forage for. As for water, birds can survive for a long 
time without water if they have food as they get much of their water from the 
seeds they eat. Also, water collects in the produce trays from the automatic 
misters, so that should not be a problem. Even if there was a concern about 
the bird, it would be almost impossible to catch without a bait and trap 
setup. ... If I was working at Hannafords I would try to make sure there was 
an opportunity for the bird to get to the back section of the store during a low 
traffic time like early in the day. Other than that there is not much to do in 
this situation." 

He also reminded me that House Sparrows are an introduced species are are 
driving out native species such as Bluebirds.  That is immaterial as regards the 
plight of this particular bird, but it also underscores why such problems exist in 
the first place.  Also, I think it could help if large stores made an effort to have 
fewer nesting places around their doorways (such as those elaborate, light-up 
signs with all the extra nooks and crannies).  

Well, back to watching the back yard and waterways, I suppose.  Many thanks 
for the reports here...especially the Christmas Bird Count totals!  I have been 
eagerly awaiting those results and will be watching here for more.