Cresent Versus Modified Excluder Entrances?

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dcsicking@gmail.com
Posts: 4
Joined: Thu Jul 23, 2020 6:46 pm
Location: Fredericksburg, TX

Hello,
We are purple martin colony managers for several years now. This year we had 18 breeding pair and fledged 71 birds. I need to add space if we are to have a larger colony. I am ordering PMCA Excluder Gourds with all accessories.
Question: which type entrances should I order, crescent or modified? I have ruled out the Excluder entrances. I currently have all crescent entrances on my apartments/gourds. They have worked well in that no starlings have entered that I have seen. We do have many starlings around that come and check out the gourds and nest boxes on a daily basis. I am unfamiliar with the modified excluder entrance. What are the pros and cons? Which do you recommend?

Thanks :)
Dan in Fredericksburg, TX
Ed Svetich-WI
Posts: 798
Joined: Tue Jan 13, 2004 10:05 pm
Location: Brooks, Wi (McGinnis Lake)
Martin Colony History: 24 Super and Excluder Gourds on two gourd racks, all SREH. Full occupancy. My philosophy is to maximize fledge % with existing cavities rather than adding gourds to grow colony, thus providing opportunities for new colony expansion. Fledge over 100 nestlings yearly from 24 gourds. Band nestlings in cooperation with state university. 2019 Adendum: Reduced colony size to 12 gourds to focus on more intensive management regimen.

I have both entrances and have never had a starling breach. Starlings try both early in the season, give up and never bother all season. I think that the Modified Excluder would be more difficult for even a smaller starling to enter based on their larger sternum. Others will chime in. All are occupied each year. Some martins, both male and female, struggle every year to enter the Modified Excluders but persist and raise successful nests. It is hard to watch the adults struggle but they have always managed. As far as I am concerned, both are excellent as SREH. I would not hesitate to use them interchangably.

Ed
dcsicking@gmail.com
Posts: 4
Joined: Thu Jul 23, 2020 6:46 pm
Location: Fredericksburg, TX

Thanks Ed. I have had success with the crescent. Thinking about sticking with that. Yes, it would be tough to watch a purple martin struggling to get in or out of the modified entrance.

Thanks again!
Dan
John Barrow
Posts: 944
Joined: Tue Nov 11, 2003 4:12 pm
Location: Corpus Christi / Sandia , Texas

Dan,

All three entrances are starling restrictive. The excluder entrances are the most restrictive due to the built in "pips" that restrict a starling from turning sideways to defeat the entrance. The excluder entrance offered with excluder gourds is the excluder 2. It is the latest design and is the most restrictive to starlings.

I have used modified excluders at three locations along the TX coast for nearly twenty years with good success. I have never noticed a hesitancy or failure of martins to easily navigate that entrance. My wife, Louise Chambers, manages a colony at So. TX Botanical Gardens offering 24 excluder gourds with the excluder 2 entrances, the most restrictive entrance. That is her preferred entrance and has worked well for her. She had 22 of the 24 gourds successfully fledge young this year (House sparrow pressure defeated total occupancy and are almost impossible to eliminate at a public colony). I recently arranged a gift of excluder gourds and a rack for Oso Bay Wetlands Preserve and Learning Center and chose the excluder 2 entrances for that location, having partial occupancy this season.

The excluder gourds are big solid gourds that will last a lifetime. I would caution that when yours arrive to install the interior and exterior porches within 1/4 inch of the bottom of the entrance, preferably 1/8 inch.

Good luck in your endeavor whatever choice you make.

John Barrow
Corpus Christi, TX
~~TEAMED WITH A MARTIN GODDESS~~

Member/Mentor-PMCA. I do regular nestchecks and participate in PROJECT MARTINWATCH!! Coordinated 3 geolocator studies-2009, 2010 & 2013. State and Fed licensed bander (retired Jan., 2020)
dcsicking@gmail.com
Posts: 4
Joined: Thu Jul 23, 2020 6:46 pm
Location: Fredericksburg, TX

Thanks John for the good advice!
One more question: If I install the inside and outside porches 1/8" below the entrance, will the owl excluder guards still fit? They seem to be rigid and the space between the guard installation points will reduce, possibly preventing the installation of the guard.

Thanks again!
Dan in Fredericksburg
johncanfield
Posts: 59
Joined: Mon May 04, 2020 5:13 pm
Location: Texas

Hi neighbor! We're about 30 miles west of you. I have 12 Troyer gourds with Conley 2 openings (and a tunnel.) The only undesirables I have are sparrows. One or two years ago I found a dead adult in one of the tunnels after everybody left for the season. I have no idea what happened to it, its wings were folded in so I don't think it was entrapment. We had a good season this year with 25+ fledged.
John
JJ Ranch
Texas Hill Country
John Barrow
Posts: 944
Joined: Tue Nov 11, 2003 4:12 pm
Location: Corpus Christi / Sandia , Texas

Dan,

You can find a picture of the modified excluder on PMCA main website in their store at the Excluder Gourd section. The ones I used were built into tunnels incorporated in natural gourds.

As far as the excluder gourd owl guards, we have not used those. IMO, owls chase martins out of gourds in the evening-night by grabbing the cavity and shaking the gourd. They then catch whatever flees out for their meal. We use the wire guards that attach to the gourd system itself and hang in front of the gourd entrance. These are intended to keep owls away from the gourd porch and entrance and not make contact with the gourd.

The excluder owl gourds do offer some protection by keeping an owl from reaching in to the back of the cavity and pulling martins out. However, if they latch on to the gourds they can still shake occupants out. In my experience martins will learn to hide at the back of a cavity and not come out, which trait is more easily accomplished by lowering and doing nest checks on a regular basis.

Unless you have a verified and reoccurring owl problem, I would worry much more about the starling problem. With any of the SREH entrances you can exclude all or most starlings, where an owl problem might necessitate the need to cage the system and might still not be foolproof.

Placing the porches within 1/4, (preferably 1/8) inch of the entrance will deter most or all starlings, which are much more numerous and aggressive than owls. However, if you make that change you will not be able to mount the Excluder owl guard to the porch without some tweaking of the angle. Others have bent them to fit; however, in a short search today, I was unable to locate an earlier video that showed how someone has done that.
~~TEAMED WITH A MARTIN GODDESS~~

Member/Mentor-PMCA. I do regular nestchecks and participate in PROJECT MARTINWATCH!! Coordinated 3 geolocator studies-2009, 2010 & 2013. State and Fed licensed bander (retired Jan., 2020)
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