Touring a 14-square-mile Delta island where sweeping cornfields will provide a home for legions of sandhill cranes come winter, a team of government officials from Mexico got a pretty good idea Wednesday how private lands can be used to benefit public resources. The visit to Staten Island was part of a weeklong tour by the delegation, which has partnered with the federal Natural Resources Conservation Service to swap ideas about how to preserve soil, water and wildlife species while fighting climate change.These issues, after all, transcend political boundaries.