bird (mis)behavior question

Perhaps someone here can help me.

There's a robin trying to get into my house. Specifically, she has been flying into one window, about once every two minutes, for 15-16 hours a day, and has been doing so for four days. She launches from various points nearby and charges straight into the window. Sometimes she'll sit on the sill and try a sort of half-leap into the glass.

Now here's the really weird part: this is the 20th year in a row that end of the house has been under spring attack. The first year it was a cardinal. We have had six or seven types of birds over the years. All beat themselves to a pulp, leaving feathers and poop all over. (I'm concerned about the bird, not the mess - just trying to paint a picture.) It will go on for weeks, and it will be relentless and brutal.

We have put foil paper over the windows, played recordings of owls, played music, hung streamers, tied balloons with painted-on 'eyeballs' to the window, covered the window entirely, shone lights from inside to out, and my personal favorite, stood at the window flapping arms and yelling. The Annual Suicidal Bird is unimpressed. Our retired, antique barn cat will sleep directly under the windowsill - granted, he's so old he's nearly immobile, but the bird does not even slow down when he's there.

We've sort of given up on actually stopping this: apparently my dining room contains the avian Holy Grail. But I really, really would like to understand WHY this is happening. I can sort of understand one bird doing it - but one bird a year for twenty years?

katie

It is birds mistaking their own reflection in the glass for an intruder in their territory, so they get all fired up, wanting to chase the "intruder" out of the territory, and if need be, do battle with it until it is gone. They can be very determined and hard to stop!

Resin

Shutter?

We've tried covering the glass with fabric or foil. Neither has worked. THe house looks pretty darn stupid, but it's not stopping the robin; right now it's bashing its poor little head into a tablecloth that totally covers the window, and which is also flapping somewhat in the breeze. I would have thought that would startle it. But no.

Time of day and amount of light doesn't seem to matter. It might habe initially seen its reflection in the window, I suppose, but there would not be a reflection now. Just a tablecloth. Sigh.

katie

He remembers where that varmint was. Last year a male Cardinal covered our cars driver side mirror with poop every day for two months.