The deep cavity of ChirpyNest resembles the natural woodpecker cavities martins nested in for most of history. A deep nesting cavity provides added protection from the long reach of owls. Since incorporating ChirpyNest, I have reversed the decline caused by owls at my site. In 2010 - 60 pair successfully fledged 241 young. Owls began attacking at my site and by 2015 my colony had dwindled to 21 successful pair and only 82 young. I developed ChirpyNest in response to this decline and in 2019 I eliminated gourds at my site as the martins were choosing ChirpyNest over the gourds. In 2019 my home site fledged 211 young from 57 successful nests.
If the martins fear an attack, I think the birds will retreat down and to the back of the ChirpyNest cavity, sensing a safer option to fleeing the cavity. This deep cavity resembles the naturally deep cavities made by woodpeckers and traditionally used by purple martins.
In 2021 my colony fledged 358 young from 89 nests! My most successful season ever.
Premature fledglings numbers (or jumpers) have gone down to almost zero since changing gourds to ChirpyNest houses. The young stay longer in ChirpyNest since the house is cooler and drier, reducing the chance of pre-mature fledging.
After reaching 103 active nests last season, I am hoping to hit 100 nests that fledge young.