Attracting Wrens to Nest

I need some help regarding House Wren nesting. I have three wren houses. Two years ago they nested in only one of the house. But last year they did not take up residence at all. My thoughts are that perhaps the locations are too near house sparrow nesting sites, which are getting more and more numerous (they've even hijacked my Robin shelf for the second year in a row).

Thoughts? Thanks.

Could it be lack of feeding habitat, rather than nest holes?

Make sure you have plenty of rough 'weedy' garden with native plants, and tangled brush piles of old branches with brambles, etc., growing through them. And make sure the whole area is pesticide-free (get your neighbours to join in, too!).

Resin

Resin,

Hmm, well the little sweeties are all around the place, just not using the houses. They perch near the houses, and I see them enjoying the neighbor's quince bush.

I provide nesting materials, though the sparrows are usually little piggies hogging it all. And I do organically garden.

I had read not to put too many wren houses together, but don't know if that applies to different birds as well.