There's the dry season ...
And then there's the "dry season."
The second half of the meteorologic dry season, say March through May, coincides with an equally parched landscape to impart the swamp with the full effect of drought. In this case, a shallow sliver of water is still holding on in the center of a cypress dome, but it was filmed in the beginning of May.
Even with today's rain my guess is, as the month draws to a close, that puddle is gone.