Ideas:

1. This 'bird' with hanging 'moe'-head is different from the one in Ea2-2:

Its body is nearly a mirror image of the common one.

2. We have seen this type of glyph in Sunday, presumably indicating the end of the day:

In the calendar of the year it seems to mark the end of summer (autumn equinox):

May we not then think that it also can be used to indicate the end of the waxing moon?

3. In Mamari it seems to be used to indicate the end of each of the 8 periods of the moon. And a total reversal is indicated in the 5th period, after the time of full moon:

In Keiti we now find what looks like a partial reversal and that before the time of full moon. Why not after? And why are there two sorry old birds before full moon? I think I know the answers.

4. However, we can see this type of bird in the period after the full moon too: