Publishers Weekly
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This passionate if unpolished account from children’s and YA nonfiction author Castaldo (When the World Runs Dry) explores how squirrels shape the natural world. These ubiquitous creatures, which have entertained and frustrated humans since antiquity, are vital to ecosystems, Castaldo explains. For example, the gray squirrel, which is common in the U.S., hoards acorns in multiple locations, but only consumes some of them. The rest end up far enough away from the parent tree to successfully germinate and grow into oak trees, which benefit a variety of wildlife and help sequester carbon and manage watersheds. Castaldo covers squirrels from every conceivable angle, examining their evolution, how they’ve been prepared as meals, and their depiction in mythology and popular culture. She pushes back on the metaphor equating “squirrel brain” with scattered thinking, pointing out that squirrels’ brains are proportionally larger than those of other rodents and allow for “exceptional problem-solving abilities.” While Castaldo’s expertise and enthusiasm for her subject is evident, the account is diminished by filler that feels more appropriate for kids (like recommendations for children’s songs about squirrels) and odd juxtapositions (at one point, a line from a speech by former president Joe Biden is co-opted to apply to squirrels). The kitchen sink approach makes this a missed opportunity. (Oct.)

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From Booklist, Copyright © American Library Association. Used with permission.

Castaldo, primarily known as an author of children’s nonfiction (Whales in the City, 2025), here turns her eye onto one of the most common and well-known animal families, the squirrels. As the author points out in her preface, the very ubiquity of squirrels makes them underappreciated and understudied. Castaldo seeks to remedy this by pulling together scattered research on squirrels (primarily grey and red tree varieties) into an entertaining examination of their lives and relationships with humans. The book covers topics such as squirrels as keystone species—many forests exist due to squirrels forgetting the locations of some of their cached nuts or seeds—or as ambassadors, city parks providing a home for people-pleasing squirrels worldwide. Introduced grey squirrels invaded the UK and continental Europe; Castaldo devotes several chapters to their ecological and social impact. Accounts of squirrel interactions with humans (love ’em or hate ’em!) make for amusing reading. Finally, a chapter on endangered squirrel species reminds us that not all squirrels are as numerous as the ones we see every day. Chapters are headlined with vintage artwork of familiar squirrels, further deepening our fascination and affection for these ubiquitous backyard friends.