I didn't read the first book in this series, so I was a little surprised by the sudden turn in vocabulary about ten pages in. I thought the illustrations were just going to be kind of minimalist and otherworldly, but then 'floogle birds' and 'farfle seeds'. It just wasn't needed.
There are some funny gags in here (Santa Vaca, 12 miles per hour, etc.). Not much of a plot: The squirrels head south with the birds, they phone the guy, the guy comes, then they all go home. Is that a spoiler? Rubin & Salmieri go for the comedy all in the characterization and the straight man / comic setup.