At times I believe that with the ever increasing pressure from European Starlings, it would be just a matter of time before purple martins become extinct! Luckily for us landlords Charles McEwen of Mocton, NB developed the SREH or Starling Resistant Entrance Hole. This development has single-handedly helped save more purple martins than we will ever be able to count.
The starling resistant Crescent entrance, which has given rise to nearly a dozen variations has virtually neutralized the threat of the invasive European Starling to our native songbirds. Many folks deal with the pressure and destruction caused by starlings entering their round holed colonies, rather than converting their entrances to SREH because of the apparent difficulties one can have in teaching your martins how to navigate such an odd looking entrance. Looking at the entrances it is no wonder, the shapes are downright strange and seem to defy logic. How would a bird get in? But trust me! They do!
As I stated before there are many types of starling resistant entrance holes, some of which are protected by patents and copyrights. Some have even touted Starling Proof entrances, though in my opinion, it is a bit premature to stake that claim. You can read more about “starling proof” entrances HERE. There are also many opinions as to which SREH is better or more effective than the next. I have only tried a handful myself and even with SREH I continue to trap non native starlings at my colony.
Most of my 30+ compartments are Conley II (also called “The Clubhouse” entrance) and crescents. I have a gourd with a modified Excluder and one with an Excluder II also. ALL fill with martins.
I must admit that at first I had some issues switching them over but eventually they got the hang of it.
If your colony is established, that is they are bonded to your site and have nested there before, they should figure it out pretty quickly. You may witness the SREH Shimmy (as I call it) which is often mistaken for the martins “not fitting” into the new entrance hole. Do not fret, these designs have been designed and tested with many thousands of martins and they will fit in it. The martin will stick his head in and make it appear as if he can not fit. He may even appear to squeeze and push, to no avail. Trust me though, if the entrance is either bought from a reputable source such as www.EntrancesbySandy.com or www.PurpleMartins-R-Us.com or comes pre manufactured, the sizes are carefully measured and the bird can fit. Be patient. Many landlords suggest keeping a few round holed compartments available. The rounds will fill first but the desire to stay together at the colony will get the other martins to eventually get in the starling resistant entrances. Of course you must intensify the battle against any starlings, as they will now be focused on the few round nests that remain. This will buy some time for the martins to become familiar with the change and master the entrances. It just will take time. A couple of days at the most.
Consider building a repeating nestbox trap or purchase one pre built. Also called a S&S trap these can trap repeatedly without resetting. Since the trapped bird is released into a holding cage, the trapped birds can tolerate it much better than a conventional nest trap. That is to say, if you leave the house for a few hours and a native bird is trapped in the repeater, they will be none the worse for wear when you get home. In a regular nest trap, the bird won’t do well at all. I would never recommend leaving a regular nest trap set while not actually watching it. Stuck in a closed off gourd or house with little air flow-It gets hot quick. Also you can stick the repeating nest box trap in a spot that is less desirable to the martins and lure the starlings away from your martin housing.
If your colony is new, that is you are still trying to attract your first pairs of purple martins, then converting them can be a bit trickier. Hopefully the martins that come to investigate your site come from a colony that uses SREH. If they are familiar with them they will enter the compartments like quicksilver. If they are not familiar with SREH then leaving from a couple of entrances to half the compartments with round entrances will work. Monitoring your housing and keeping starlings out becomes even more important to these new colony sites and trapping and neutralizing is key. Local Starling population control can reduce the pressure form these invasive birds and increase the possibility of attracting and keeping your first pairs of martins.
Now for the downside. Though SREH are a wonderful tool that has helped martins to flourish in otherwise starling infested areas, their are risks. Though not common, Wing Entrapment can kill if not caught. I have encountered this problem a couple of times at our colony and you can read about Wing Entrapment HERE. When using SREH it is recommended that you look at your colony twice a day to observe for any martins that may be entrapped. Entrapment usually happens at the peak of martin breeding season when martins will often have territorial fights within the nest. The birds back up to the entrance while fighting and get their wings stuck. Lowering your housing and gently removing the stuck bird will not only save the life of the martin that is stuck but the 1 or 2 other martins that (I guarantee) are in the gourd with it.
Unfortunately there are no sparrow resistant entrances, when it comes to Purple Martin houses. So getting a good trap either nestbox or a baited trap becomes essential.
REMEMBER, when using traps of any type, monitoring is essential to preventing harm to native birds that may be inadvertently trapped. Native birds may not “learn” that it is a trap and are often caught repeatedly. If you are unable to monitor your traps they should be disabled while you are away.
Credits and copyrights are/may be in effect for SREH designs
Dually entrance design by Ken Landry
ACE entrance designed by R. C. Moser and developed by Bob Flam.
Excluder entrance designs by Duke Snyder
Conley entrance designs* by Willie Conley