i put 7 houses around my pond, 18 years ago...found out some interesting information..i had one really nice redwood house, it was up for several years and the martins never nested in it..they filled the trio metal houses first, then a couple home made ones i "had", then the newest plastic houses..they actually went for 2 years after i put the plastic houses up before they would nest in them..i think its because the top is dark green, and it has to get really hot in there..but the metal houses are still nested in first..the ark game and fish folks put out a pamplet several years ago, it said the martins do not send "scouts" and ate very few mosquitos...
gave me another reason not to believe anything the govt says.
heehaw