How to tell what is nesting in the compartments?

[neckbone]

My T14 has been up a week today. I opened up everything to place pine straw in each box.
To my surprise there was a twig or more in every nesting box (more in some).
I saw a House Sparrow coming out of one box.
Not being able to watch who comes and goes from each compartment, how can I tell if other than PM are nesting when I look in?
Do I wait for eggs and destroy them as a deterrent?

[Forum Admin]

You don't want to destroy eggs unless you know they belong to house sparrow or european starling - and it's better to get rid of those two before they get to laying eggs. Twigs are often a sign of house wrens, a native, protected species, so they can't be harmed, but you can remove incomplete nests daily. Put up a single box for them away from the martin system. It seems early for house wrens in PA, but a photo would help confirm whether it is or not. House sparrows usually build a big ball of grass with tunnel entrance.

Here's an ID of nests: https://www.purplemartin.org/uploads/me ... id-378.pdf

[neckbone]

I'm screwing up somehow. I thought I understood that pine straw should be placed in the nest boxes. It would seem silly to now remove it to discourage some species of bird.
Should I not use pine straw?

[Forum Admin]

Leave the pine straw in place - you said the bird brought in twigs, remove those, but still try to ID the bird as well.

[threelilkids]

Wrens will put twigs in many holes they like to have false nest near by, just in case . Mary