Starling Resistant Entrance Holes (SREH's); Martins' Preference for Deep Cavities and Starling-free Housing is Stronger than their Preference for Round Holes.
From: Ken Kostka, Edinboro, PA
Date: 12/12/99
Time: 6:48:59 PM
Comments
When debating martin "preference," for entrance
hole type at typical, unestablished sites, I believe we should not be asking
whether martins prefer SREH or round holes, but whether martins prefer starling-free
or starling-frequented housing. The answer is obvious. I believe that SREH's
should be widely used at both established and unestablished colony sites, and
that SREH's will not lessen one's
chances of attracting martins. In many cases, SREH's will enhance one's chances
of attracting martins by eliminating harassment by starlings. Martins can
and will use SREH's at new sites.
Ever since the starling resistant entrance hole (SREH) was first developed by Charles McEwen, PMCA’s 1992 Landlord of the year, a mistaken belief has grown that martin housing at unestablished sites should have traditional round holes so as not to discourage cavity-hunting martins. I believe this line of thinking is erroneous because: (1) it is based on observations at established colony sites, and (2) the "starling harassment factor" is not given enough weight. Martins may prefer round holes, but they have an even stronger preference for starling-free housing when investigating new sites.
(1) When landlords at established colony sites convert their round entrance holes to SREH’s in the off-season, the martins are suspicious and hesitant to enter (at first) because they are accustomed to using round holes, and they know something has changed. It is the slight change that makes them hesitant, not the entrance hole! In every case, the martins eventually entered when given enough time. Nobody has ever lost their martins by converting to SREH’s. (Changing entrance holes is not a radical architectural change. Radically changing the housing is known to cause site abandonment, like when landlords unknowingly switch to a whole new style of house or housing system in the off-season).
(2) Starlings and martins both have a strong preference for deep (10-12" long) cavities. Most people attempting to attract martins aren't willing or able to effectively control starlings. People must work during the day, and even when traps are set up at the perimeter of the colony site, a seemingly endless supply of starlings will attempt to move into the martin housing and harass cavity-hunting martins in the process. So while martins may prefer a round-holed, deep cavity if starlings aren't a factor, the truth is that starlings are usually a big factor without SREH's.
Put another way, I believe that the average landlord
(who cannot rigorously eliminate starlings) is more likely to attract martins
by offering deep cavities with SREH's, than by offering deep cavities with round
holes or small cavities with round holes. (Martin's love deep cavities.)
By the way, I believe this is true whether talking about houses or gourds. Starlings
will use
large, free-swinging gourds, both natural and plastic; I have ripped their nests
out of both type. The only reason starlings are thought to avoid gourds is because
either most gourds offered are too small, or because houses with deep cavities
are available at the same site. Given a choice between a very large gourd or
a very small house cavity, starlings will go for the gourd, in my experience.
One landlord, Ken Fecker, once took down all his houses thinking this would
eliminate his starling problem, but the starlings began to move into his large
gourds within a few seasons..
Again, martins will use SREH's at unestablished sites. One landlord I know of modified a Trio Musselman so that one compartment was enlarged to 6 x 6 x 12" with an SREH, and left ten cavities at 6 x 6 x 6" with round holes. He attracted one pair of breeding martins his first year. It was an SY pair, and they used the deep cavity with the SREH! By the way, I don't think it's a bad idea to leave a few round-holed shallow cavities to enhance "snooping." Just be sure you can convert them to SREH's with deep cavities in case a pair of martins decide to use one. Last spring, I erected a Trio Musselman with three of the cavities converted to 6 x 6 x 12" with SREH's. Two pair bred in the house. One of them used a deep cavity with an SREH and one used a small cavity with a round hole. They ignored a wooden house with 8-9" deep cavities with round holes that was 25 ft. away. The wooden house had been at the site for many years but never attracted martins. I'm convinced that the reason the wooden house was never colonized is because although the owner was constantly shooting starlings off of it, he couldn't keep up with them, and they would harass the martins. Furthermore, I had offered other deep-cavitied aluminum houses at the same site in previous years, but without SREH's, and I was constantly removing starling nests. I encourage everybody to re-read Charlie McEwen's Landlord of the Year article from Update 3(4). It's at http://www.purplemartin.org/LOY/LOY1992.html.
I recommend the original CRESCENT-style SREH's, as I have seen too many failures with the Oval-style SREH's. Also, the SREH is most effective when placed flush with the porch and inside floor.
Ken Kostka
