I bought the triliogy and have tested out all the DVDs.  It appears that volume 2 is the most well received of the three and the one I would recommend.  It's funny to watch my cat watch it bc she looks behind the TV trying to find the birds.  I turn this on sometimes when I'm leaving the house, by the time I get home, she doesn't seem to be paying attention anymore but figured she'd at least enjoy the sounds.