WDC type of SREH entrance showing it to be impregnable by this European Starling

A starling tries to gain entrance to a nesting cavity but fails after 37 attempts over a period of 8 minutes. This bird had been sheltering itself every night for some two months before the entrance was swapped out from a round hole to the WDC version of a Starling Resistant Entry Hole. This video pretty much proves that starlings--or at least this one--are unable to gain entry to a cavity protected with this style of SREH making such housing safe for purple martins.

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