[Tweeters] Nestbox (pre-made cavity) nesting swallows

[Mark Borden via Tweeters]

Dear Tweeters,
I also live on Whidbey Island, and would say that the population of Violet Green and Tree Swallows here has been stable. On my home (5ac)  property I have about 75 nest boxes, and most are occupied. Currently we have young in the boxes ranging from ready to fledge, to just hatched. Many clutches have already fledged this season. 

All (about 150, if you include our 83 acre farm) of my entrance holes are 1.5 inches. I have about a dozen boxes with 1.25 inch entry holes, and those are occupied by either wrens, or chickadees, but not swallows.

To see a fencebox video go to medicalwizard9 on X.

The primary key to avoiding house sparrows is to place the box far enough from escape cover. As a Falconer, I have pursued house sparrows with the smaller accipiters. The speed of a House Sparrow across the open is no match for a Cooper’s Hawk, and they immediately seek escape cover, often successfully. They do not like to be in the open, and all of my boxes that are more than 50 feet from escape cover are occupied by swallows, solely. Only just fledged swallows are susceptible to predation by the accipiters.  Adult swallows are occasionally taken by Merlins.

The primary key, in my experience, to increasing Violet Green and Tree Swallow population is to install nest boxes with 1.5 inch openings that are a distance of at least 50’ from cover.

Mark Borden MD
Coupeville, WA.
360-632-748four


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