How can I attach wooden bird houses to a concrete post?

[Ohmnomnom]

I have 3 tall concrete posts in my garden. They are the old fashioned washing line posts that used to have pulley systems to hang your washing outside.

I'd like to put bird houses at the top of each one but can't think of a way to securely attach them. I could screw brackets into the back of each box then wrap wire around the post and thread it through. It gets really windy out the back and I'd be devastated if the box fell down with baby birds inside Is there a really obvious way I'm missing?

Can you just attach them to the actual post, use a concrete drill, some bird boxes come with metal plates with holes in them for the wcrews.

Maybe. I'd have to call a handyman for that as climbing ladders to drill into concrete is not in my skill set

Cable ties.

Bracket of some sort

Oooh cable ties! That's brilliant. I wonder if you can get ones designed for outdoors.

you can buy bird box brackets on amazon, or maybe something like a hanging basket bracket attached to the post then a birdbox which has a "handle" and you hang the box off it.

Construct a wooden cap that fits over the top of the post and fasten the bird house to that. If you made it at least 15cm deep, it might wobble but it wouldn’t blow off

You need to make sure they are on the north side with the post acting as some shelter, but they still might get too hot.
Neighbour lost all chicks last year as he put them on a hit south facing wall.