Typical of S&K, these entrances incorporate the latest improvements. Here is the S&K crescent entrance....
We have had great success with the S&K crescent and its flush-mounted porch every year since 2004, and never had a starling invasion of our many S&K gourds.
So it was with some optimism that I adapted some of these entrances to try on our two school sites with starlings in the Conley II Troyer Horizonals.
To use them I cut off the stubs of porches I had left on the Troyers and cut open the entrance plate. The S&K entrance was attached using three 3" quarter-inch bolts.
Coverting all four Troyers on the rack took about thirty minutes. The original gourds were left in place as two of them contain martin eggs.
I should add here that the starling has laid three eggs in the last three days (there were none on Saturday) and will pobably lay again tonight or tomorrow. What we have here is a motivated starling.
For the first ninety minutes the results were encouraging, the female starling repeatedly returned to the gourd, crouching down, sticking her head inside and trying to get in without success.
All three of the other Troyers on the rack are occuppied and those martins easily adjusted to the new openings.
Finally, as dusk closed in, the female starling made a concerted and susutained effort to enter the gourd.
At late dusk, she finally succeeded. This is what the south end of a starling looks like squeezing into an S&K crescent with porch.
Ok, she will probably lay at least two more eggs to the three she has before when commences to incubate, then two weeks of incubation after that. I have some time here.
Out of curiousity, Round Three is going to be the S&K Clinger entrances that Dave sent us with wing-entrapment guards and a flush mounted porch.
My concern is that the martins in the other Troyers may have difficulty with this entrance type even though they easily adjusted to Conley II's and S&K Crescents.
I have never used Clinger entrances before. Is there any reason to suspect that the martins will have problems learning it?
Anyhow, if the Clingers are also breached, round four is gonna be Modified Exlcuder plates.
Rest assured, this will all end badly from the starling's point of view regardless.
Thanks,
Mike Scully
I "think" I have a couple extra Dually and Ace plates I can send too you if you want them. I will look and send you a PM if I do. 
This post made me look a little harder this morning before I started my work on the house and low and behold, I see a bird with a huge load of crap in it's beak headed for a Troyer Horizontal with Modified Excluder. It comes back out and a Martin dive bombed it so, I got my .22 Rifle for a better look. I'll be a Son of a Biscuit eater, sure enough, on the backside where I can't see very well, they had taken over a gourd and stuffed it full of junk. From what I saw, 1 was entering, the other bringing more and more nesting material. I am not sure if one or both were breeching or not? While I did not find any dead Martin's, I lost 1, possibly 2 nest of egg's, as the next gourd in back, the egg's were not viable and threw them out. It took 1 1/2 hour's to get them from my Son's newly installed bedroom window however, Reap It they did 
I have not been paying much attention to my SREH gourd's but, look at my round hole's often. I have been very busy, and just have not taken the time to watch. I have noticed more Starling's this year feeding on the ground then normal. I usually kill 6 a year and these 2 make 5 this year. I will have to take more time to watch, but cannot all the time like I am used to.
All these young punk's and their modern conveniences. 
I reached for my air rifle and headed outside. The starling flew off, and then out of the gourd came its mate. 