To prevent thief from our farms we could add some security gadgets in it. Some of the common ones are alarm system, cctv, etc.
There are two most use alarm system, one is the vibrate sensor type and the other one is the motion sensor type. The Vibrate type alarms will on if it sensed vibration. This happened when someone hacking the walls or the doors. If the thieves enter thru the Entrances hole without causing vibration then the alarm will not on or sound.
Where as for the motion type the alarm will only on if it sensed movement. Normally it uses the infra sensor beam. It could be placed anywhere in the farm especially at the entrance hole. A timer is set on certain hour for the alarm to function. Some good alarm only sense large object that moved so small birds' movement wouldn't trigger the alarm.
The other way is placing steel bars at the entrance hole. Many are doing it. Somehow if the holes between the bars are not big enough it will obstruct the birds when they fly in and out of the farm.
(thieves really not welcome here...ha..ha..look at the steel bars.)
For this purposes the owners need not to install alarm which he could save money and no worries about alarm is triggered on during lightning or false on which could disturb neighbours.