I thought he was exaggerating when my friend called and said he had snakes in large numbers in a water trap in his front yard. I grabbed the camera and drove out to his farm. I was amazed when he lifted the iron cover to expose the mass of reptiles inhabiting that small area. Practically every crevasse housed a serpent. They were mainly Bull Snakes with some King Snakes and Rat Snakes. The temperature was in the 70’s, and the snakes were lively and active. There were no venomous snakes that I could discern. We agreed that the large number of Bull Snakes would result in fewer or no rattlesnakes since we have believed for ever that Bull Snakes ate or killed rattlesnakes. I decided to research the actual facts about Bull Snake vs Rattlesnake. I was surprised at the results.
Byron Shipley is a rattlesnake researcher at the Plains Conservation Center in Aurora, Colo. His information is precise and carefully documented. One of the main myths is that Bull Snakes kill or eat rattlesnakes and  that having them around will eliminate the risk of being bitten by a rattler. In all the literature he reviewed, there were only 2 instances of rattlesnakes being found in the gut of a king snake out of 1,000 king snakes examined. That is only 0.5% of the entire list of prey items which is negligible for population control. It has been documented that rattlesnakes and Bull Snakes hibernate together. They can’t cross-breed since the rattlesnakes bear live young, and the Bull Snakes lay eggs.  
Rattlesnakes seem to disappear in mid-spring. I know we see very few of the Massasagua rattlers at the Bottoms after the frequent sightings in early spring. That is due to the fact that rattlesnakes become mainly nocturnal after mid-spring. Bull Snakes are busy day and night in their feeding patterns. Bull Snakes seem to favor warm-blooded animals and bird eggs. I wondered about their effect on pheasant and quail populations, but cannot find any reliable info. Rattlesnakes eat other snakes, lizards, amphibians, and all types of warm-blooded animals.
I was somewhat disappointed to learn that Bull Snakes share space and don’t really mess with Rattlesnakes. Bull snakes are cranky and have a much worse attitude than rattlers when disturbed or caught. Brian and I found a little Massasauga in one of the goose pits at the Bottoms when we were duck hunting last fall. He seemed to appreciate being lifted out of the cold water in that pit and returned to the warm earth of the shore when we exited the marsh. He will probably be the star of a rattlesnake-in-the-marsh photograph one of these days. They are one of the less-appreciated species in our marsh-- but everyone has a place.  
Doc