A playful, curious little hippo wanders away and is found by its mother. As Little Hippo (safely) strays from the herd, readers see joyful mud baths and splashy water play. There's a brief moment of childlike moping when Mama Hippo pulls Little Hippo back to the herd, but it's not long before it's grins and giggles once more. Mason's warm illustrations are irresistibly front and center in this board book. The rhyme and cadence of Abery's text gives the story a lullaby feel, with a rich vocabulary. Patterned stanzas--"Little Hippo / puzzling, / nuzzling, / finds a red-billed bird"--work wonderfully when read aloud, and words like "romping / stomping," "bustling / hustling," and "sulking" expose little readers to new verbs. The second word in each rhyming pair is printed in blue, contrasting with the overall purple type. The illustrations have a watercolor feel, with softly mottled grays, pinks, and purples for the hippos' skin, and include nuances like shadows from passing birds and light filtering through water. Little Hippo's face is drawn with minimal features but is nevertheless incredibly expressive, with joy and even remorse easily discernible. Abery and Mason also created the simultaneously publishing Little Monkey, with similar themes of an adventurous little animal who is rescued and loved by its mama. The text follows the same format of rhythm and rhyme paired with lovely illustrations. A delightful animal outing. (Board book. 6 mos.-2) Copyright (c) Kirkus Reviews, used with permission.