That is a Lincoln's Sparrow with the blue-gray supercilium, buffy malar stripe, thin streaks on buffy flanks, and clean streaking on the back.
The streaking on the flanks of this bird is too well-defined for a Swamp. The back color is just fine for a Lincoln's and the really clean lines are good, too. I think the beak appears larger because its head feathers are flattened.Looks more like a Swamp Sparrow to me. Lacks the gray back of Lincoln’s and the bill is too big, also much more likely than a Lincoln’s in New Jersey, especially in the spring. Habitat is exactly where you’d be seeing Swamp Sparrows too. Basically in the water, foraging along a grassy edge.
Song Sparrows have larger bills, obvious mustachial stripes, messy streaks on the back, and they're just a different color.
Compare to the bird in this thread: https://www.birdforum.net/showthread.php?t=389739
My first impression here was Lincoln's, too. I would have thought a Swamp should show a full, bright rusty cap by May 10th, as well as even more rufous wings than this bird.
The rusty cap is actually one of the reasons I thought it was a swamp. I was actually convinced it was a swamp, it just looks like one. But then I started comparing the back streaming of the two species and I’m much less sure. It’s definitely not a song sparrow. This is Lincoln’s/swamp and I’ve been swayed towards Lincoln’s away from my initial impression, although I still find the face, cap and bill to look much more swamp-like in the photo. Those things are more easily distorted Or misinterpreted in the photo as compared to the back streaking. It’s probably a Lincoln’s.
Agreed.....why not include the definitive photos??????
My point was that if a photo is not definitive and you think you have either a 'lifer' or just a basic bird, go with the basic bird.
But in this case with these photos, it is a lincoln all the way.