Need some help with ferals......

My friend has feral cats that are coming in her opened window to eat. The window is left open for my friends indoor/outdoor cats to come and go, closing it is not an option. However, the feral cats are messing all over the house.

What can we do to stop them from messing in the house? My friend is going to be leaving Thursday for an extended trip and wants the ferals out of the house.

Does anyone have any ideas? I have already broached closing the window, but she refuses as she will not leave the cooler running while she is gone, and that is why the window stays open, so that her house cats can get out.

She is leaving food for the ferals, because it is a mother and at least two babies, outside on a table. But they eat that and then follow the other cats into the house through the window.

Any advice, help, suggestions, yelling, screaming, drinking, (Vodka, please) , tranquilizers, sodas, seltzer water, anything will be gratefully appreciated.

I can't see how she can stop some cats coming in and out and not others, without installing a selective cat flap, like those operated by magnetic collar keys. Most cats learn very quickly how to use one, but there may not be time for all that before she leaves on the trip!

The answer is simple- shut the window. Leave the inside/outside cats inside. Keeping a window open is not safe- she is opening herself up for theft-

She can trap the outside cats, get them fixed and re-release them into another safer area or into another colony.

They will continue to come indoors after the food, they will spray and poop because that is what feral cats do. keep the window open 24/7 and deal with the cats, or close the window and allow her cats to be indoors all the time. Those are her options, or trap the cats and vet them and relocate them.

Thank you so very much for helping me. I have been begging her for months to shut that window and keep her insiders in. She claims that they will go crazy, that they need the outside, but I disagree. I have four very happy inside cats who do NOT go crazy (unless they feel like it), and are only outside with me, when they are on a leash. I don't know what to do. I can't seem to make the point with her and the window issue is non-negotiable with her.UUUUUGGGGGGGGGGHHHHHHHH

MA basically said it all - I just wanted to say HI!!!!!!!