two martins lost to wing entrapment

[Craig Dyer]

My first nest check of the season began on a sad note. I found one adult female martin dead in the aluminum crescent entrance hole. Her wing had become trapped. As if that wasn't bad enough, I found another dead adult female entombed within that same compartment. They had probably been fighting over that particular cavity. This occurred in a Lonestar Goliad with porched crescent entrance holes. I plan on creating a small radius in the corners of all of the crescent entrance holes. I hope this eliminates this tragedy from reoccurring. One would think that the manufacturers of aluminum housing would change their tooling and start making the crescent entrance holes with broader corner radii.

[John Miller]

I'm sorry this happened. This is something I've been studying on my own for some time after experiencing the same.

I'm not sure if you can round the corners in a flush crescent. Maybe. Rounding corners helps prevent single wing entrapment, but sometimes we also get "double wing." I suggest that in addition to rounding corners, you consider the weather stripping idea that I've suggested here in other treads to make a "bumper guard."

Clean the surface and stick on one piece at each side about 1.5 inches in length. You can run another slightly longer piece across the top. Set each piece back about one-eighth inch from the entrance. This will create a "bumper" guard. If a bird is pressed sideways against the flat plane of the hole, it should be less likely that wing could then protrude. I use Frost King “Weatherseal” that’s ¾” wide and 7/16” thick.

John

Update 2012...use automotive universal weather stripping, not home kind. Automotive is a more sense rubber and may create a better "bumper." The home kind is very spongy and I had one entrapment with it. either, the aluminum must be very clean for it to stick. I don't recommend using on plastic, such as inside gourd tunnels.

[Craig Dyer]

Thanks John. Yes, I have seen your post regarding the weather stripping. Maybe that alone will do the trick. This is the first time I have witnessed wing entrapment. I don't want a reoccurance. I wonder how common it is.

[Al Denton]

I think John's idea was a very good one. I put these foam weather strip guards on my Coates two years ago, and they are holding up very well.

[John Miller]

How common.... No one knows. I collected reports here for a while. Aluminum crescents with sharp corners are the mostly commonly reported, but I bet many cases go unreported. John

[Sparky]

Craig,
I found this very common when I had aluminum Coates housing. Since, I changed to a wooden T-14, I haven't seen any entrapment. Possibly changing from aluminum to plastic door/entrance material will help as well. I've never seen the problem occur on a plastic gourd, so this may be the way to go. For some reason, the aluminum doors were a problem for me.

[Carlton]

Sorry that happened Craig. Heartbreaking.

I noticed when I bought my MSS-12 house a couple years ago that the manufacturer had switched over to a new form of the crescent entrance. I was crimped over on the inside and more rounded on the "corners". At first I was concerned about it as it looked small to me but the birds loved it and SO FAR there have been no problems. I only use that type of crescent now on my MSS-12 and 8.

Carl

[Guest]

At first I was concerned about it as it looked small to me but the birds loved it and SO FAR there have been no problems. I only use that type of crescent now on my MSS-12 and 8.

Carl

Carlton, can you provide a photo of the type you are referring to? I'm about to start converting (all you guys have made me into a sreh convert ) and I want to do it well the first time.

[Carlton]

Lilyrose,

I hope these are clear enough to show what I am talking about. Notice how the MSS-12 and MSS-8 entrance panels are crimped over at the bottom edge on the inside and how the corners are modified to help prevent entrapment. I think having the crimped over bottom on the inside helps the martin push it's way out of the SREH too. The old Trio entrances were designed with the sharp angle corners and the non crimped entrance. These new ones seem better to me.

Good luck!

Carl

[Guest]

Oh, thanks so much. It looks like the curved side of the crescent is cut, then trimmed along the straight edge, and bent over at a 90 degree angle, facing inside the nestbox. Is that what I am seeing? What is it about the crescent that causes wing entrapment? Is it the thin metal that has no depth to the edge?

[Guest]

I just took a 3/4" rasp on a drill to ease the corners of all my aluminum crescents. I haven't had another martin hung up since I did it. You should be able to make out the shape in the attached pic.

[Guest]

I think it's the sharp corner of the crescent that does it, not the door thickness.

[Guest]

I haven't had another martin hung up since I did it. You should be able to make out the shape in the attached pic.

Looks good, Mr/Ms Gragg. Does it keep starlings out too? What about the crescent entrances works for starlings? Is it the opening height from bottom to top, or the width, or both? Is the chest depth of starlings the cause of their usual inability to enter?

[Guest]

(it's John) Yes you have it exactly right it is the dimension from bottom to top (1 3/16") that keeps them out. Some have found there are extremely smart/persistent starlings that are able to rotate their breast and breach the crescent. This problem gave rise to the excluders and subsequent variations (in the picture I sent the gourds have I think what is called WDC excluders mounted on tunnel intrances I purchased from Sandy Bunn). Those little nibs on the bottom prevent the breach. I must say that I have never seen a starling breach my crescents. I think it was Emil who told me about easing those corners, and I had had several wing hang incidents till I made the modifications, so it's worth doing.

[Guest]

Thanks John. I have a couple of drills, but the only rasp I am familiar with is a wood rasp (the kind you grasp and move up and down the wood grain). What kind of 3/4" rasp can you use in a drill? Are you talking about the drill bits that have a surface that looks like a wood rasp? Why doesn't it shred the edges of the metal? Thanks.

[Guest]

I guess I would call it more of a rotary file than a rasp. See the pic for something similar to what I used. I think I got it at a home center.

[John Miller]

John Gragg

I too would like to know specifically the kind of tool. I tried a small grinder stone on my drill and found I made a mess. Yours look good. P.S. editing now...I see your photo.

Indeed this may prevent most wing entrapment in crescents.

There are occassional reports of "double wing" in various openings, including the WDC (modified excluders) and in two-inch round holes on occassion that people put through interior walls. There's even a double wing entrament photo of double wing in a Trio keyhole entry in the archives.

Now, it may be that double-wing entrapment begins with single wing, which may actually be easier for a bird to with draw with the rounded crescent than a WDC, because of the humps. It's probably also a matter of how much the bird is being attacked on the inside. If you're a bird and got your wing loosely stuck out and somebody is pecking at you on the inside, your inclination may be to open both wings to shield yourself and try to back out the hole both wings open. That's all I can figure as to why double wing occurs sometimes and it's why some sort of addition bumper guard may be helpful too.

John M

[Guest]

I clamped the door in a vice, and essentially just barely rode the file along the straight bottom, being careful just to go straight across until it got all the way to the corner. Then I blended it in with the crescent arc above, if that makes any sense.

[Guest]

Thanks John. I've seen those at HD and Lowe's, and there may even be one out in our toolbox (I think there really may be ). I think I can handle what you described pretty well.

[Glynn B - LA]

Hello J Gragg

I brought this old post back up to see if your crescent modification is still working for you and your martins. I am very interested in trying this. Did you ever figure out exactly what the tool name is that you used to make the mod. I want to try this on my Alamo with crescents.


Thanks: Glynn