1. This type of glyph shows two young birds kissing.
2. I guess that their youth is shown by the shapes of their beaks, not with a hook at the tip like the adult birds have.
3. I think this type of glyph was used for the reunion of the Sun Bird with his Summer Wife.
4. Possibly this reunion is connected with a specific point in time, after winter solstice but before spring equinox.