Crow or Great Black Hawk (GBH)

[h2y]

Crows are easily mistaken for GBHs because they are similar in size and both appear solid black but there is a distinction: the GBH has a white band on it's tail, which is especially noticeable while in flight.

Huge difference: like all raptors, GBHs grab their prey with long, strong legs with talons so they can latch onto a column, etc with one leg & secure any age martin with the other.
Meanwhile, crows grab their prey with their beak. A mere songbird, with relatively short, twig-like legs with "perching" claws, not talons, they are incapable of the above feat. Not completely innocent, opportunistic crows will snatch hatchlings from open top, tree nests of other species and PM hatchlings from shallow, single room housing but with minimal design/safeguards/overhangs that prevent perching, your PMs are relatively crow-safe. So, if 100% black crows are snatching your "pinkies", it's a housing problem.

If a black bird, with any white coloring, carries off a martin while clutching it underbelly, it's a hawk problem.

Great Black Hawk bio: https://biodb.com/species/great-black-hawk/
Crow bio: https://biodb.com/species/carrion-crow/

[h2y]

Seems like the majority of hosts that have crow issues use gourds. Is it horizontal, vertical or both type of gourds that are prone to crow predation?

I've been using barn houses for 26 years & have never seen a crow on them and that's with a murder of crows nesting a 1/4 mile away in a stand of pecan trees. They fly by daily and stop to eat corn & sunflower seeds that are 25 yards away from the PM houses. Evidently, they don't see an "opportunity" (all rooms are converted to 2-room suites, a necessity). I don't add perches, guards, etc to my houses which predators could also utilize. The integral short porches & roofs suffice (for perches) + fences, hi-wires, trees, etc. Crows are very welcome here, even fed, as we want to be included in their "protected territory" to deter hawks, foxes, etc.

However, I'm out of porch room for more houses and already have a bunch of stored gourds for future expansion but don't want to create a crow issue.

P.S. While looking outside 15 minutes before dark last night, saw what had to be a Great Horned Owl on the ground & into a tree 50 yards past the PM houses. Could just see the silhouette but no mistake about the huge head and the wing heft. He was a big boy. Figured I'd have a house ripped to smithoreens this morning but no.
Update: 2 mornings later, found the attached Great Horned Owl feather under a PM house but still no house damage noted.