I've seen a few porcelain pieces with these birds and wave-type decorations recently. I believe it dates from the first half of the 19th century because of the quality. Am I right?
Possibly late 19th or early 20th century in my opinion. Not sure about the base though.
I would think Daoguang to Guangxu. What I find odd is that there are swallows together with a butterfly on the same item, and even more so with the large chunk of what could be grass or something similar.