In addition to habitat in general being a second subject, specific phenomena can be a second subject, too. Below are a couple examples of photos that are about birds and also about the influx of sargassum that has hit the Caribbean several times in the last few years. This has been a significant occurrence, impacting both man and nature. Sargassum is important to shorebirds at the moment, and shorebirds help tell the story of sargassum and its impact.
There are plenty of other opportunities to combine birds with events or phenomena to create engaging images. Trees without leaves or dry pond beds can tell us about seasonal changes and unusual droughts. I wish I had spent more time photographing cattle egrets as they fed on grasshoppers trying to escape from this brush fire. The presence of a bird is really more evocative than photos of the flames themselves.