We have found that monkeys, baboons and elephants are breaking a lot of our cellular camera traps antenna. These animals love to chew on and manipulate the antennas usually until they are snapped off or completely destroyed. We use standard omni directional 16 cm screw-in black plastic mms antennas with an adjustable knuckle at the base.
We have tried coating in chili with some success until it washes off. We have also tried using a metal or PVC cover but have found this reduces signal.
I would be interested to hear from anyone else who has found a solution to this problem or a decent inflexible metal antenna that can be used. If I find something in the meantime I will keep you posted.