We hit the trailhead a bit early since everyone was there.  We hiked down the boardwalk and towards Bull Run (river) accompanied by lots of birds singing in the trees.  Later on we stopped to try to identify a few and were pleasantly surprised at the diversity of birds around this sliver of a park along the river and in the flight path of Dulles International at times you could seemingly reach up and touch a 777 flying overhead.  The trail had quite a few bridges as you might expect, but a few were quite bouncy, although very sturdy.

We walked along the river up a few fairly steep hills.  Before the next little hill and before crossing a small stream I heard a bird singing loudly in the bushes.  We stopped long enough to spot the bird and to my surprise, it was one of the most strikingly beautiful birds out there, an Indigo Bunting https://www.allaboutbirds.org/guide/Indigo_Bunting/,.  This particular bird had a surprising long song, which he repeated many times, moving from shrub to tree and back again.  We just stood there in admiration before moving on.  We walked for another 15 minutes and spotted a wood shelter high up on a bluff above the river so we took advantage of the view and the seat for a rest.  Soon we observed a bird flitting about and singing in a tree slighly below us.  Checking a couple of bird websites, we were able to identify the bird as a Black-Throated Blue Warbler (https://www.allaboutbirds.org/guide/Black-throated_Blue_Warbler/id).  We continued on until we reach some Civil War earthworks which was about the 3.5 mile mark and almost 2 hours into our walk.

We walked back and oberved more Indigo Buntings (groups of them in places) and then spotted or third warbler, a Black and White warbler, https://www.allaboutbirds.org/guide/Black-and-white_Warbler.  I have this bird in my back yard each summer (and an occasional Indigo Bunting passing through) but it was still nice to see it here.

We got back to our staring point around 1:30 pm, making for a good 4 hour hike.  This is a great gem of a park in Northern Virginia and definitely needs a revisit.