Models of wildlife cameras for secret use?

I need cameras for wildlife recording which can be hidden in places where there is very high likelihood of them being stolen. They should be small and with long lasting batteries, no flash, just infrared. Operating range is important, ca 12-15 m is good. I do not need high quality and colour pictures - these features are sacrificed for the sake of secret use. Well, Reconyx are possibly good, but they are big and I suppose will use flash. So please, advise me. Price is not a problem, if there are good chances to hide camera, if not - then I will need to use cheapest ones and make a lot of replacements. Thanks a lot. LB