I have homemade ant traps on all of my hummingbird feeders.  I have 
seen non-hummingbirds perch on the ant traps and drink or bath in the 
water.

To repeat what was said here earlier, they are easy to make.  Take a 
spray paint can lid or anything that resembles one, drill a tiny hole 
in the center of the bottom of the inverted lid.  Push a stout wire 
through the hole and bend it into an S hook.  The wire should be long 
enough that the top S hook lies outside the cup.  A dab of hot glue 
or aquarium cement around the hole, top and bottom, will insure that 
it does not leak.  Fill it with water and enjoy.  If you see start to 
see ants again, it either means your trap has tried out or that the 
surface of the water is covered with dead ant.

I have noticed that Ruby-throats become much less

Ruby-throats will eat small insects and small spiders.  They capture 
insects by hawking,gleaning the  from leaves, snatching from spider 
webs.

It is my personal observation that as Ruby-throat numbers go up, some 
threshold is past, beyond which the share food rather that expend 
energy dogfighting each other.  Most of the times they only eat one 
to a feeder, no matter the number of ports.  But when there are too 
many, the swamp out the aggressive behavior and I have seen as many 
as 6 on a 6 port feeder.
-- 

Rick Hollis
North Liberty, IA