Where do squirrels live? Wherever they can.

We have always had a big population of squirrels in our neighborhood, probably because we have many big trees, including our coast live oak.  Oaks in California had a big mast year in 2021, which means they produced many more acorns than usual.  The population of squirrels increased significantly, which is typical of mast years.

Some of the big trees in our neighborhood before they were pruned or removed. Google Earth

In the fall of 2021, several of our neighbors radically pruned their trees, presumably because they wanted more light in their yards and their homes. They also cut down several trees including a big, old tree behind us and several fruit-bearing trees down the street from us.   

Same trees after pruning.

We didn’t give it a lot of thought when that happened.  We respect the rights of our neighbors to do what they think is best on their property. I remember thinking it wasn’t nesting season for the birds, but I also should have given some thought to the squirrels. (California Department of Fish and Wildlife biologists have defined the nesting season as February 1st through August 15th.) Even if I had, I doubt that I would have objected because it wouldn’t have been neighborly.  I have always confined my activism on behalf of trees and wildlife to public land that belongs to everyone (although I have also tried to help property owners to save their trees at their request).  

Fox Squirrel, the species in our neighborhood. Source: University of Utah, Natural History Museum

 We didn’t realize that our neighbors’ trees were the homes of many of the squirrels who are now searching for new homes.  Squirrels have gnawed holes into the eaves of our roof and the wood shingled siding of our home.  They are living in the walls of our home.  If we can’t move them on to new homes, they will soon have their babies inside our home. 

We have found a service that uses humane methods to coax the squirrels out of one-way doors and seal their holes behind them. If you have a similar problem, I recommend the Wildlife Detectives in San Rafael. 

I had not predicted the impact of tree pruning and removal in my neighborhood.  As we try to deny squirrels access inside our home, it only recently occurred to me why the squirrels are seeking refuge inside our home and our neighbor’s home after 15 years of living in peace with them. 

This has been a humbling experience because I considered myself fairly knowledgeable about both trees and wildlife.  Apparently I’m not.  Humans aren’t very good at anticipating the consequences of the choices we make in nature and our choices rarely take wildlife into consideration because our understanding of their needs is limited.  That’s one reason why I often advocate for the “leave it alone” approach to land management.

The Big Picture

The squirrels looking for new homes in our neighborhood are a reminder to keep wildlife in mind when making changes in our gardens and homes.  Our gardens are food and habitat for wildlife. 

But protecting wildlife goes far beyond our own homes because the activities of humans have an impact on wildlife on a population level.  Here are a few examples of projects that have kept wildlife in mind…or NOT!

  • The federal infrastructure bill includes $350 million to construct wildlife road crossings.  Such road crossings help to prevent serious accidents caused by cars hitting animals and save animal’s lives.  California is building a wildlife bridge over the 101 freeway to connect split portions of the Santa Monica Mountain National Recreation Area.  A vegetation bridge is also being built over the Ventura freeway in California.  These wildlife corridors benefit wildlife populations by preventing genetic isolation that can weaken the species. The California Governor’s budget for 2022-2023 includes funding to build more wildlife corridors. 
  • Scientists have learned it is possible to relocate burrowing owls before their underground burrows are destroyed to build new developments.  The owls are enticed into their new homes by surrounding them with the poop of other burrowing owls.  The owls are more willing to stay in their new homes if they believe other owls are living there.  Just like people, they want to live among friends.
  • We must convince native plant advocates to quit destroying important food and habitat for wildlife.  The birds don’t care if Himalayan blackberries are not native.  It is a primary food source that is more productive than its native relative.  When Himalayan blackberries are sprayed with herbicides—as they are regularly in San Francisco—the birds are being poisoned as well.   

There are many more opportunities to take wildlife into consideration in everything we do.  Please write a comment to add more examples. 

Unseen City: A tribute to urban nature

It was pure pleasure to read Unseen City (1).  Unlike most nature writing, Nathanael Johnson asks readers to notice and appreciate the urban nature that we tend to take for granted.  Ironically, the plants and animals that we see every day and in great numbers do not get the attention they deserve.  Most nature writing tends to focus on rare and remote species to which we have little access and often laments their absence where we live.  Conservationists often advocate for expensive programs to reintroduce rare species to urban centers where they haven’t lived for decades, if not centuries.

Johnson’s focus on the ordinary species around us is refreshing.  We were happy to take a break from the usual hand-wringing about loss of biodiversity and instead enjoy the richness and beauty of the nature we have.  It is our loss when we ignore the nature we have. Johnson’s intense focus on urban species reveals that they are every bit as interesting as the rare species we seldom see.  Johnson’s approach to nature is analogous to the optimist’s “glass-half-full” approach to life.

Another appealing aspect of Johnson’s approach is that his story is told from the perspective of a young father, introducing his toddler daughter to the mysteries of nature.  One of our primary concerns about the museumification of our parks by native plant advocates is that children are being deprived of the opportunity to interact with nature.  Being required to stay on trails or observe from behind fences is no way for children to appreciate the complexity and beauty of the natural world.  Johnson takes his daughter deep into the weeds to experience nature in a physical, tactile way. 

A few examples of the homely creatures in our cities

Johnson wrote his book while living in San Francisco and then in Berkeley.  So, the species he encounters and studies are those with which we are all familiar.  Here are some of the creatures he tells us about, with a few of the interesting things we learn about them.

  • Pigeons are reviled by many serious bird watchers. In fact, they are remarkable creatures in many ways.  They mate for life and they are extremely devoted parents.  They tend to nest in the same place and their ability to find and return to that nest from long distances is one of the reasons why humans have formed intense relationships with them.  There is a long tradition of keeping homing pigeons that are raced by their keepers in competitions that occur all over the world.  The pigeons are taken long distances from their nests and then timed on how long it takes them to return home.  Johnson tells remarkable stories about how pigeons overcome challenging attempts to prevent them from finding their way home.
  • Eastern grey squirrel. Creative Commons

    Squirrels are both extremely agile and very resourceful. Here is an example of how squirrels defeated an attempt to keep them out of a bird feeder: “…squirrels had to climb up through a vertical pipe, leap onto a blade of a spinning windmill, cling to it, and then sail off on the right trajectory to land on a platform.  Then they had to go paw over paw upside down along a suspended chain that passed through a series of spinning disks, negotiate a revolving door, run through a slack canvas tube, and keep their balance while crossing a pole covered with slick spinning rollers.  From there, it was a six-foot jump to another tunnel, through which they had to ride a sliding vehicle made to look like a rocket ship by pushing it along with their paws.  Finally, there was an eight-foot jump to the food.” (1)  I retell this to story to spare our readers the pointless effort of trying to prevent squirrels from raiding their bird feeders.

  • Turkey vulture in San Jose, California by Dan DeBold. Creative Commons

    The turkey vulture is another underappreciated bird. They eat primarily dead animals and many of those animals died of diseases or toxic chemicals and are rotten and maggot infested when they are finally found (by smell) and eaten by the vulture.  The digestive and immune system of the vulture is capable of detoxifying chemicals and killing bacteria and viruses in the dead animal.  In other words, the vulture is cleaning up the remains of dead animals.  India has learned the value of vultures the hard way.  They killed many of their vultures with an anti-inflammatory drug they were feeding to their livestock.  When their vulture population dwindled, they were buried in dead animals, many dangerously diseased and toxic.  We eradicate animals at our peril because we often don’t understand the roles they are playing in the ecosystem.

Defending novel ecosystems

In addition to asking his readers to appreciate the positive qualities of the creatures in our cities, he also asks us to reconsider the deep prejudice against them that has become the conventional wisdom.  Plants and animals that people believe were transplanted by humans into places where they did not exist in the distant past are considered “alien invaders” that dominate their predecessors, driving them out and reducing biodiversity.

This narrative, which originated in academic science as “invasion biology” in the 1960s, has become a popular story with the media, which is always attracted to scary stories.  The media is significantly less interested in the peaceful resolution of their horror stories.  With few exceptions, an introduced species that initially seems to be a problem eventually fades into the woodwork to become just another player in the ecosystem.  Johnson uses the Argentine ant as one of many examples of an introduced species that spread rapidly, but 20 years later has nearly disappeared.  In other cases, a species initially considered an unwelcome intruder becomes a valuable asset, such as zebra mussels which filter pollution from lakes and have become a source of food for diving birds.

Novel ecosystems are the future

Johnson concludes his book with this reminder that novel ecosystems have been created by human disturbance and that we should be grateful for the plants and animals that are capable of surviving our abusive treatment of the planet:

“The species that I’ve written about here are, at best, invisible, and at worst, reviled.  We honor least the nature that is closest to us.  As Courtney Humphries put it in Superdove, ‘We create and destroy habitat, we shape genomes, we aid the worldwide movement of other species.  And yet we seem disappointed and horrified when those plants and animals respond by adapting to our changes and thriving in them.’

“Because they are associated with human disruption, the organisms that spring up from our footprints look like corruptions of nature.  But I’ve come to see it the other way around:  These species represent nature at its most vital and creative.

“Nature never misses an opportunity to exploit a catastrophe.  When humans bulldoze and pave, nature sends in a vanguard of species that can tough it out in the new environment.  These invasive species are not nature’s destroyers, but rather its creators.  They begin setting up food webs, they evolve and diverge into new species.  Because humans purposefully import exotic plants—along with the insects, seeds, and microbes we accidentally bring in from around the world—cities are remarkable centers of biodiversity.  These creatures crossbreed, hybridize, eat one another, form cooperative relationships, and evolve.  And so, at a time when thousands of species are at risk of extinction because of our destruction of wilderness, new species are springing up in the new habitats we have created.” (1)

Worshipping the rare at the expense of the common

The ONLY known Raven’s manzanita plant is in the San Francisco Presidio. Its exact location is a secret to protect it.

Vast sums of money are being spent in often futile attempts to reintroduce rare plants and animals to urban environments where they have not lived for a long time.  The National Park Service and San Francisco’s Natural Resources Division are having little success with their efforts to reintroduce Mission Blue butterflies.  After over 30 years, the National Park Service has still not successfully germinated endangered Raven’s manzanita from seed.  These fruitless efforts are not just wasteful of resources, they also inflict damage on the environment by using pesticides and setting fires to eliminate competition and destroying trees to increase sunlight on rare plants and host plants of rare insects.

The veneration of rare plants and animals is often at the expense of the plants and animals that are adapted to present environmental conditions.  In Unseen City Nathanael Johnson invites us to place greater value on the ordinary creatures who are capable of living with us.  We can treat them with the respect they deserve by not destroying them in pursuit of a fantasy landscape populated by fantasy creatures that are not capable of surviving the changes we have made in the environment.

  1. Nathanael Johnson, Unseen City: The majesty of pigeons, the discreet charm of snails and other wonders of the urban wilderness, Rodale Wellness, 2016