You will most likely spot them when they fly from one patch of reeds to another, so watch for birds in flight low over the reeds. You often only get a glimpse for a second or two while in flight, and if you're lucky, they'll land somewhere where you can still see them.
The American Bittern is much larger than the Least Bittern. In my experience, despite their larger size, they are even more difficult to spot than the Least Bittern. They are often found in cattails and bulrushes. When I first started searching for them, I looked mostly in taller reeds, but I now find them in reeds that are much shorter than their full height; they stay hunkered down low still very well hidden. Look for a larger brown brown heron-like bird with a neck streaked brown and white. In flight, the American Bittern has two-toned brown wings. They are darker on the back and outside edges of the wings. You can often see a black streak down the sides of their throat. My favorite quality of the American Bittern is their ability to point their bills up while looking down.
You are most likely to see them when they are moving in the reeds or in flight. Look for movement and then wait to see if you're lucky enough for it to present itself. Or, look for a bill sticking up that looks like the tip of a reed. My first few sightings of this species were of them flying away from me as I was walking right by them--it's really infuriating. For more on locating American Bitterns, you can see another post I contributed to the Birding is Fun! blog.
I think it's common for people to identify any large brown heron as an American Bittern, and this is unfortunate because immature Black-Crowned Night Herons are also brown. I often see immature Black-Crowned Night Herons misidentified as American Bitterns on the web. I even found one online bird identification site include a photo of a Night Heron in the entry for the American Bittern. But immature Black-Crowned Night Herons have white specks on their wings, and they do not have a two-toned brown appearance to their wings in flight.
|Immature Black-Crowned Night Heron|
(note white specks on wings and more uniform brown color)