This is the reason I purchased the new Bushnell Trophy Cam HD Max Trail Camera for the 2012 season . It will trigger and film without any indication of its presents. No more will the elk spook when they are being filmed at night. I only use this older model for daytime recordings which doesn't give you a true picture of what is happening in a location. Trail cams have taught me that it is common for elk to be active all night long making the morning and evening hours even more critical. It is very easy for the elk to move to completely nocturnal behavior when pressured.
Keep hunting till oh'dark thirty.
Hondo
