I have some friends that have had issues with trespassing and here are a few suggestions...Put up alarm signs. "protected by Sentry alarms" etc. The idea is the trespasser may believe that they have triggered an alarm and that the authorities or owner are on the way.
Another suggestion for land that is served by electricity is to put motion detector lighting in. Put it on your main road and when you drive in at night it will trigger and light up and also can make an alarm sign more visible. This can also be connected to a buzzer. If someone passes through our main gate a buzzer goes off at our house letting us know someone has entered. This can work to startle a trespasser.
Finally, consider occassionally carrying a holstered sidearm with you when you know neighbors kids or others are in the area. Make sure they see you carrying it. A friend of mine has a big Colt pistol that he carries frequently when he is on his property for a number of reasons. He has had some break ins and vandalism to deal with. There is something very intimidating about a stern looking land owner walking around with a cannon strapped to his hip that will make you think twice before wanting to cross him!
