My window feeder looks bone dry and haven't seen a bird near it for a couple weeks. I guess it's just leaking, a Kingsyard. Bad design, the seal is just rubber in a groove. So, I went a-shoppin' on Amazon and Ebay looked at a lot of stuff, settled on this:
Kingsyard 2 Pack Window Hummingbird Feeders w/ Ant Moat, Strong Suction Cups - 8 Oz Leak Proof & 5 Bee Proof Feeding Ports $22.99
By and large excellent reviews. Neat stuff:
Looks like it can't leak
A real moat to keep ants out
The moat + nectar tray lift out easily for maintenance
People say the suction cups are real good, mostly
con: Says holds 8oz but one reviewer said more like 6oz.
This kind of design doesn't allow nectar to be stored in a cylinder, so when the nectar gets too low the birds won't reach the nectar.
Got the 2 pack so I can prepare a feeder and swap with the old one any time of day. Last year I cleaned etc. the window feeder and saw a little one settle on the perch and get real frustrated because it couldn't find its juice!