Depends on how the song is interpreted. The intention is probably “by the 𝑛ᵗʰ day of Christmas, my true love had given to me [list of 𝑛+(𝑛–1)+...1 items]” but the actual grammar means that by day 12, you'd have received 𝑛(13–𝑛) of the 𝑛ᵗʰ item, or
12 drummers drumming
22 pipers piping
30 lords-a leaping
36 ladies dancing
40 maids a-milking
42 swans a-swimming
42 geese a-laying
40 gold rings
36 calling birds
30 French hens
22 turtle doves
12 partriges in pear trees
Total is 184 birds. By day 7, only 69 birds, up 50 % from 46 by day 6. At least the number of received birds stays constant (23) on days 8-12. The geese technically-a-reproducing are not accounted for, as the eggs might not be fertilized and take several weeks to hatch.
Plus, you have to provide room in your house for a huge number of new lodgers. Drummers, pipers, lords, ladies, maids... and then you've got to find a place for all the birds.
Your "true love" is clearly taking advantage of you by unloading all of this onto you and calling it a gift.
From days 8 to 12 your true love gives you milkmaids, dancing ladies, leaping lords, pipers and drummers. Human beings. As gifts. Which makes eating the birds feel a lot more okay.
This carol was written back when Christmas was a mere 12 days long. Now Christmas starts in mid-October. "On the ninety-ninth day of Christmas, my true love gave to me, ninety-nine wall beers..."
People used to routinely eat just about every bird there was. The only reason nobody bothers with songbirds is that they're too small to be worth a damn. Remember the passenger pigeon? The extinct one. Yeah we literally ate that into extinction.
Fair enough. Although I don't think you'd need to bother with the songbirds in this instance seeing as you've been gifted a years worth of geese, French hens, and milk. Unless you're required to feed all the other various humans you've been gifted as well. I guess then it would be time to crack into the turtledoves.