The third column is color-coded. Yellow means the species was seen the last day of recording. No color means it wasn't seen.
But there are two other colors -- red and blue.
Red means the species was seen and it just up the list, becoming more common!. Blue means the bird wasn't seen and moved down the list. It's ephemeral since the chart changes every day.
What's that got to do with sapsuckers and sandpipers you ask? Yesterday the Yellow-bellied Sapsucker moved into sole possession of 183rd place on the island, beating out Baird's Sandpiper, which dropped into 184th place. The sapsucker's score is 300 (days seen since the inception of the database), and the sandpiper's score is 299.
To see the swap you'll have to check the chart today. Tomorrow things will be different!