The sparrows are worse than they have ever been. My arms are so sore from lowering the trap 3 times a day to remove the sparrow nest.
Hope,
First, some photos to illustrate my points....
The above are typical of MOST active martin sites in my area.
The point is, as long as there are open cavities, on a site that has previously hosted a colony, the sparrows alone are unlikely to run off all the martins. It may look absolutely horrible, but martins will come.
Remember that MOST martins i=have to breed under these sorry conditions.
A second point is MERELY REMOVING NESTS WILL NOT GET RID OF SPARROWS. ONe year I tried it on five houses like these every week for three months, there was NO reduction in sparrow nests in all that time. Unlike most wild birds, house sparrows do not appear to abandon the nest site when the nest is destroyed, they just rebuild.
What just removing the nests DOES do is cause the sparrows to invade adjacent cavities occupied by martins and destroy their eggs and small young.
Also, while it may seem like every sparrow in the neighborhood is attacking your housing, my experience over the last ten years has been its usually only two or three pairs out of many. Eliminate THESE and your problems drop off exponentially.
My advice is to target the exact individual sparrows in their cavities. As some have pointed out, very effective entrance door traps are available.
Failing that, shim down the entrance to 1 1/2" so that sparrows can enter but martins cannot. I use the plastic lids from food containers....
If it were me I'd order a sparrow door trap and wait for it to arrive, so that I could catch the sparrows without having to place anything in their nest.
Failing that I would carefully place a mousetrap or glue trap inside the nest, after shimming down the entrance as described so martins could not get in.
Mike Scully