Both refined beet sugar and cane sugar are sucrose. I can offer a few
alternatives.
1) hummingbirds generally disappear in the spring and summer to their
breeding grounds, returning to urban/suburban feeders beginning with
the post-breeding dispersal in August. Perhaps your sugar change was
coincidental.
2. perhaps the brand of beet sugar has a dessicant or preservative not
found in the brand of cane sugar you bought.

I have been reading stacks of hummingbird papers all summer and have
not come across anything about beet sugar vs cane sugar. There's
plenty on "don't use honey," "don't use artificial sweetners" and
preference for sucrose over glucose, fructose, maltose, etc.

Sounds like the makings of a backyard science project...

"John Shelton - ext. 4051" wrote:
>
> To whoever posted the article about hummingbirds' dislike of beet surgar.
>
> Thank you, thank you, thank you.
>
> I watched the hummingbirds shun my feeder all summer. Switched to cane
> sugar and Voila! the next day two hummingbirds are vying for control.
>
> John Shelton
> Portland, Oregon

--
Mike Patterson The common view of science is that it is a sort of machine
Astoria, OR for increasing the race's store of dependable facts.
mpatters at oregonvos.net It is that only in part; in even larger part
it is a machine for upsetting undependable facts.

----- H.L.Mencken
http://www.pacifier.com/~mpatters/bird/bird.html