We then drove over to Willow Run Airport and made a quick pass through the service drive. Lots of Savannah Sparrows singing and perched on the fence. No Grasshopper Sparrows. We saw several Eastern Meadowlarks and a couple of Bobolink. This one landed on the fence near the car and allowed a discrete photo from the car. As we admired the bird an Upland Sandpiper sang its wolf-whistle call across the road (out of site). We didn't stick around to look for it as security was patrolling the area and we didn't want to get stopped.