Over the last several years I've noticed something questionable. You can learn stuff by watching wildlife. I can't really say what I do for a living but I can say this, there's an old saying there; "The only reason they hire you is so they can fire you." Anyway, I have been through the same neighborhood for several years off and on. Some parts of the area the squirrels will strip down the pine cones and anything else they can devour. Poor pecans don't stand a chance.
That brings me to my observation. I know from my childhood that squirrels will travel miles looking for food. I can be on a street and the pecans have been tore up! A couple of streets over and they rot on the ground. I have notice this for years. I often wonder if there ain't something in the ground that the trees are taking up and the squirrels detect it thus leaving the pecans alone. It's said that in the buckeyes not all of them are poisonous and a squirrel will eat the ones that are not and leave the others. Probably just an old wives fable.