We're seeing the red-tails on the perch and even on top of the box at times. That means the perch has to come down, unfortunately. I don't think the top of the box would be anywhere near big enough for a red-tail nest, so I think they were just using it as a convenient spot near the perch.
In any event, can you all email me (and send a pic if you can grab one) whenever you see any red-tails on the top of the box or the perch (we'll take it down this weekend)? I want to see if this is going to be a continuing (growing) problem, and I can't watch the webcams all the time...
Steve
Okay, the perch has been removed, so we shouldn't see any more red-tails hanging out by our kestrel nestbox. I don't seriously think they're interested in using the box for anything other than a convenient spot from which to perch and hunt, and given all the spikes on top of the box, it should prove unusable by them for that purpose. Not to say they can't/won't occasionally stand on top of it even with the spikes, but there are better places to sit and wait now that the perch is gone.
There was some concern that having the RTHs around would prevent any kestrels from nesting, but I don't think that should be a problem for several reasons. First, red-tails are pervasive all over SoCal, and there are plenty of birds (including kestrels) living in the same environment with them. Just as lots of other, smaller birds live in the same environment as kestrels and Cooper's and sharp-shinneds, kestrels and Cooper's and sharp-shinneds and others live alongside red-tails and red-shouldereds and such. They've lived alongside each other for hundreds of thousands of years.
Second, they should be hunting different things...red-tails hunt rats, mice, voles, rabbits, etc., while kestrels hunt lizards, bugs, and occasionally small mammals. By and large, they're not competing for resources here in our area. Even if they are, they appear to resource partition, as we've seen both living around us for many years now.
Lastly, red-tails don't usually hunt kestrels (they may occasionally hunt birds, but not in a falcon-like manner). Pale Male notwithstanding, red-tails are perch-and-pounce or soar-and-stoop hunters, looking for ground-dwelling animals. (Even Pale Male, who eats pigeons, usually takes them on the ground or in bushes, using a "brush crash" maneuver). Kestrels are just not a mainstay of red-tailed diets. Not to say it couldn't happen, but it seems fairly unlikely to happen.
So, by now, we've done just about all we can...we've put pigeon spikes on top of the nestbox to keep predators off the top, we've removed the perch to keep red-tails away, we've positioned the box optimally (facing north towards the open space hunting areas...it worked last year), etc. At this point, it's "wait and see". And keep your fingers crossed! Say your prayers, hope for good Mojo, whatever you believe in... :)