One of the disadvantages to having predatory cats is that they occasionally bring me "gifts." Shortly after installing the pet door, I woke up on a lazy Saturday morning, rolled over, and found myself nose to peak with the remnants of a dead pigeon.
One of the cats had killed the pigeon, brought it into the house, gripped it by its neck, and shook it. At the foot of my bed, there was an almost perfect circle of feathers.
The cats also seem to enjoy leaving dead frogs and lizards in my bedroom slippers. I have long since learned to shake out my slippers before putting them on. Insofar as I live in rural Arizona, learning how to shake out my foot ware hasn't been a problem as I routinely do this to check for snakes and scorpions.
On the brighter side, I am also saving a small fortune in kitty litter. Although I continue to maintain litter boxes in the house, I haven't had to clean or change a box since I opened the backyard. The cats now do all of their stuff outside and they even managed to select a sandy area in the furthest corner of the yard!
On warm days, the cats can be found outside - either lying on a paving stone to absorb the sun's warmth or crouching in the shade of a plant.
Having appropriated the backyard from the wildlife, the cats are even making use of the bog garden. They have stopped drinking the "hard" tap water I've put out for them in favor of drinking cool crystal clear water from the pond.