SREH Wing Entrapment of Purple Martins

So not even a week ago I wrote a blog entry entitled “Switching Martins From Round Entrances to SREH” and in that post I mentioned Wing Entrapment. Well this morning I look out my window and lo and behold a case of entrapment staring me in the face.

For those not familiar with wing entrapment, it is a phenomenon that is increasing due to the advent of SREH. It is basically when a martin gets stuck in the SREH (Starling Resistant Entrance Hole). Without removal the bird will ultimately die as will any birds that are stuck within the compartment itself. Though I am still a strong believer of SREH, entrapment highlights the need to be an active participant in the conservation of purple martins.

A customer asked me only today if getting Starling Resistant entrances were worth it with the threat of entrapment. My response was that the cases of death by starling would always be more common place. That the threats to adult martins, nestlings and eggs is much greater than the risk of entrapment. Never mind the fact that a martin house devoid of martins and producing starlings makes life difficult for all other cavity nesting birds. So in starling prone areas, SREH are a vital component that requires vigilance on the part of the martin landlord.package of weatherstripping foam

A case in point of why doing walk unders is so important. The ASY female would have surely died, had I not freed her. Oddly enough, no other martins were in the gourd. The worrisome part of this case of entrapment is that it occurred on a tunneled entrance that I had placed a wing entrapment protector made of 1/2″ insulation foam weather stripping. Placed above the Conley II entrance, the strip of stiff foam is supposed to (in theory) extend the distance from the foam tapeopening making it less likely for the bird to be able to lean against the opening and have a wing pop through and be stuck.

The PMCA has recently began selling (at cost) a plastic wing entrapment protector as part of a study to determine its effectiveness. The idea for those protectors came from the discussions on several purple martin forums. These discussions brought about the foam weatherstripping modification.

Here are the details of this case of wing entrapment.

1. SY male martins present this AM

2.Troyer horizontal gourd

3.Conley II entrance non-traction stripped tunnel (original)

4.Partially modified troyer neck (NOT cut all the way around as now recommended) though in looking at the interior of the martin she was stuck in such a way that this does not appear to be an issue. It almost seems that her body became stuck due to some conflict that was occurring on the outside of the gourd rather than a fight on the inside as what is usually seen.

wing entrapment tunnel interiorIt is important to note that entrapment can happen on any type of gourd or house that has SREH. My previous cases of entrapment have been on a troyer and on a S&K gourd. One with a Conley II entrance and one with a clinger entrance.

In the worst case scenario of delayed discovery of wing entrapment, the results can be devastating with the deaths of 1 or more birds. But through vigilance and monitoring of your site the benefits of using SREH entrances far outweigh the risks involved.  Though in satellite colonies or purple martin colonies that are not monitored daily, wing entrapment may be cause for more concern. Other techniques to control starling populations, a phone number to call if trouble is detected should perhaps be posted or even more frequent monitoring in the time frame where SY martins return, should be employed.


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