During last summer, I noticed an increased damage in my container garden. After several observations I noticed these are not cats (which the dog would have chased) but crows. (Slightly different than the ravens). More precisely, the hooded crow. http://en.wikipedia.org/wiki/Hooded_Crow
The increase coincides with the time people in the surrounding neighborhoods began using firecrackers with the intention to drive crows and pigeons away.

Later I find that watered containers are more susceptible to damage. I then decided to fill a container with water and place it among the plants. The crows would drink water from the container and the plants were usually left alone. I noticed the water became murky too quickly. Not immediately apparent, but later I noticed that what appeared to be the result of algal growth, was actually food scraps tossed by the crows into the water. They may be smarter than many would think and it is possibly their attempt to raise the water by throwing stuff inside the vase. (I remember I read a story about that, and crows may actually do it!). It was clearly food they carried when last time I noticed there are body parts of birds and rodents inside.

So my question is, did anyone face that problem with carcasses in the water? I thought of using shallower containers but those smaller ones can be easily tipped over by the crows, then they start again dousing for water under my plants. Using a larger container where I can place plants that will feed on the minerals in the murky water is impractical because it is restricted by space. They would normally leave the stones which are scattered nearby, so I guess the practice may be different than I thought.