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Its hard to judge how big the holes are from your photograph. But if those blocks are wood, and the holes dead-ended, they may be 'native bee'* nesting blocks. More info here:
*Honey bees are not 'native' bees as they were 'imported' into the Americas some centuries ago.
Last edited by Rader Sidetrack; 01-28-2018 at 02:52 PM. Reason: Vance is correct
USDA Zone 7A Elevation 1400 ft
leafcutter bee blocks is my guess, Bumbles use cavities and mouse nests.
I'm seeing perforated sheet metal. It looks like half holes at the end and I don't see any depth. A picture that includes a reference for size would be helpful as would a statement of size and material.
I don't even have a first guess as to what they are.
I say nesting space for leafcutter bees, too. I've seen these in alfalfa fields to increase seed yield.
(1975-1980, and now since 2011; maintain about 10 hives; Zone 5b; 15" rain; 5500')