Between 3-5 (at least) immature Prairie Warblers were flitting about in High Pines area of Duxbury Beach (MA) 8:30am Aug. 27, 2009.

After reviewing the extensive descriptive info in Peterson's Field Guide to Warblers of North America, I'm comfortable saying these were all immatures (Pg 80: "Narrow, split whitish eye ring separates all fall immatures from adults"). I'm a bit stumped as to gender because the grayness of the cheeks (auriculars) suggests the female, yet the boldness of the striping on some of the individuals suggest the male. Those with less bold striping almost certainly must be females. Two photos (#9 & 10) show underside tail shots that correlate nicely with the picture of a Prairie's tail pattern in Peterson on page 105.

Personal note: the book doesn't emphasize how obvious and solid the gray auriculars were on these birds and how evident the coloration was in the field.