Podcast Summary:

New Books Network – Nancy Castaldo on “Squirrel: How a Backyard Forager Shapes Our World”
Host: Dr. Miranda Melcher
Guest: Nancy Castaldo
Date: February 9, 2026

Episode Overview

In this engaging episode, Dr. Miranda Melcher interviews Nancy Castaldo about her book Squirrel: How a Backyard Forager Shapes Our World (Island Press, 2025). The discussion explores the ubiquitous squirrel—from its surprising diversity across the globe to its misunderstood role as an ecological engineer, cultural symbol, and sometimes, a city pest. Castaldo shares fascinating insights into squirrel behavior, history, cultural presence, and the importance of human coexistence with this often-overlooked mammal.

Key Discussion Points & Insights

1. Why Squirrels? (01:16)

• Nancy Castaldo’s Motivation:
  • As an environmental educator and science writer, Castaldo shifted from writing for young readers to her first adult book, motivated by the omnipresence and overlooked importance of squirrels.
  • Quote: “Why squirrels? ...Why not squirrels? They are everywhere, but we do not know everything about them that I feel since they seem to be everywhere, we should know.” — Nancy Castaldo [01:34]
• Squirrels are both entertaining and frustrating; they are often the first wild mammals children encounter.

2. Squirrel Diversity—More Than Meets the Eye (03:06, 04:02)

• Species Count & Range:
  • Nearly 300 global species, including tree, ground, and flying squirrels.
  • Lesser-known members of the family include chipmunks and groundhogs.
  • Quote: “People see one species, so they think there’s only one species around them... But we don’t often realize that the squirrel family is very large.” — Nancy Castaldo [04:09]

3. Conservation: Endangered Squirrels & Hidden Vulnerabilities (05:41)

• Hidden Threats Despite Ubiquity:
  • Local abundance doesn’t equate to global security—some species face extinction from habitat loss, climate change, war, and wildfires.
  • Story Highlight: The Mount Graham squirrel in Arizona is isolated atop a single mountain, gravely threatened by wildfires.
  • Squirrel populations in conflict zones, like Ukraine, are at risk from warfare.
  • Quote: “There are endangered species, endangered squirrel species, that most people don’t even think they think they're so prevalent.” — Nancy Castaldo [06:15]

4. Unknowns in Squirrel Science (08:44)

• Gaps in Knowledge and Research Funding:
  • Many squirrel species remain unstudied due to inaccessible habitats, nocturnal habits, or lack of research funding.
  • Squirrel behaviors, especially around food caching, remain mysterious.
  • Quote: “We don’t know what we don’t know. That’s part of the problem.” — Nancy Castaldo [09:56]

5. Squirrels in Culture, Folklore, and Art (10:30)

• Cultural Ubiquity:
  • Squirrels appear in mythologies, oral histories, songs, art, and media—often reflecting admired or frustrating traits.
  • Memorable Moments:
    • Native American legends credit squirrels with teaching humans to make maple syrup.
    • Norse mythology features Ratatoskr, a mythic squirrel on the tree of life.
    • Castaldo found a coin depicting Ratatoskr in her great-grandmother’s coin purse.
  • Quote: “You can see how beloved and also how frustrating our squirrels can be in the observations that find their way into all of these stories and art.” — Nancy Castaldo [13:25]

6. Squirrels and Urban Parks – A Manufactured Relationship (14:09)

• Historical Reintroductions:
  • Squirrels were intentionally reintroduced into city parks in the 1800s (e.g., Franklin Park, Philadelphia) to reconnect people with native wildlife.
  • Squirrels became beloved urban creatures and tourist attractions, but this sometimes led to unintended ecological consequences.
  • “They weren’t always there... But as cities grew... native wildlife is pushed out... Folks in Philadelphia decided... it would be good for their souls to encounter native wildlife.” — Nancy Castaldo [14:30–15:00]
• Squirrels in Central Park (17:58):
  • Wealthy city dwellers constructed elaborate squirrel houses; a recent “squirrel census” aimed to count populations, but such efforts are rare.

7. Pets or Pests? The Squirrel’s Split Reputation (19:41)

• Duality of Human Perception:
  • Squirrels are loved by some, despised by others—cuddly pets, social media stars, but also agricultural pests and the cause of power outages.
  • Quote: “Everybody has a story that focuses on them as a joy and entertainment or a nuisance factor.” — Nancy Castaldo [20:31]
• Invasive Interlopers:
  • Squirrels brought as pets to new countries (e.g., North American gray to the UK and Italy) have displaced native species.
  • Personal Anecdote: Castaldo spotted a familiar gray squirrel in a park in Turin, Italy—a jarring example of invasive spread.

8. The Challenge of Coexistence (22:50)

• Managing Wild Neighbors:
  • Research now focuses on how to manage and coexist with squirrels, especially in spaces like backyards where human-squirrel interactions are frequent.
  • Quote: “How do we coexist with our native wildlife, with wildlife in general?” — Nancy Castaldo [23:50]

9. Historical Highlight: The Great Squirrel Migration of 1968 (25:20)

• A Forgotten Phenomenon:
  • Amid major global events in 1968, the eastern US experienced a massive squirrel migration caused by a bumper crop (“mast year”) followed by scarcity.
  • Reading Excerpt (25:21–29:50):
    • Squirrels crossed mountains and rivers en masse, making newspaper headlines.
    • This event shows how ecosystem shifts can ripple through populations—including us.
  • Quote: “It was so interesting... going back through squirrel research and finding squirrels popping up in that same year...” — Nancy Castaldo [25:21]
  • Squirrels’ role as seed spreaders, prey, predators, and ecosystem keystones is highlighted.

10. Squirrel Intelligence & Myth-Busting (30:57)

• Caching Behavior:
  • Squirrels’ food-storing habits are highly organized, not random—some sort nuts by type and size, remember their locations, and even use deceptive tactics when observed by rivals.
  • Quote: “That research is showing that it’s much more methodical... squirrels do sort their nuts by, by nut variety and type and also size. They do not forget where they stash them…” — Nancy Castaldo [32:08]
  • Squirrels are smarter than the “scatterbrained” stereotype.

11. Looking Forward – Squirrels and a Changing World (34:30)

• Future Challenges:
  • Some species are already evolving physically in response to climate change.
  • Castaldo hopes her book will spark more research and support for wildlife coexistence.
  • Quote: “We’re even finding that squirrels, certain species are changing their physicality, their actually their structure evolving based on warming temperatures now...” — Nancy Castaldo [34:35]

12. Castaldo’s Next Research Chapter (36:21)

• Future Projects:
  • Continuing to work on misunderstood species (project yet to be announced), Castaldo is dedicated to highlighting the overlooked creatures that shape ecosystems.

Notable Quotes & Memorable Moments

• On the central question: “Why squirrels? They are everywhere, but we do not know everything about them that I feel since they seem to be everywhere, we should know.” — Nancy Castaldo [01:34]
• On folklore: “There’s a Native American legend about an oral history story that talks about how squirrels helped humans discover how to make maple syrup ... There’s a wonderful Hindu story about squirrels helping ... It doesn’t matter how small you are, but you can make a difference.” — Nancy Castaldo [11:04–11:44]
• On squirrels as pets and pests: “Squirrels are loved as beloved pets and entertaining wild mammals. But also pests... Everybody has a story that focuses on them as a joy and entertainment or a nuisance factor.” — Nancy Castaldo [19:41; 20:31]
• On their intelligence: “Their caching behavior is now being researched further...squirrels do sort their nuts by variety and type and size. They do not forget where they stash them.” — Nancy Castaldo [32:08]
• On coexistence: “How do we coexist with our native wildlife, with wildlife in general, when we are attracting animals to our bird feeders in the backyard?” — Nancy Castaldo [23:50]

Useful Timestamps

• Introduction & Why Squirrels? – 00:05–02:45
• Squirrel Diversity – 03:06–05:08
• Conservation & Endangerment – 05:41–08:19
• Gaps in Squirrel Science – 08:44–10:10
• Folklore & Cultural Significance – 10:30–13:38
• Squirrels in Urban Parks – 14:09–17:58
• Pets vs. Pests – 19:41–22:30
• Invasion & Coexistence – 22:50–24:45
• Great Squirrel Migration of 1968 – 25:20–30:35
• Squirrel Myth-Busting – 30:57–34:17
• Looking to the Future – 34:30–36:06
• Upcoming Work – 36:21–37:40

This lively and thoughtful conversation highlights the rich, unexpected world of squirrels and challenges listeners to view common creatures—and our encounters with wildlife—with heightened curiosity and respect.