Welcome to The STEM Sessions Podcast. I am your host, Cody Colborn
California Biodiversity Week kicked off Sept 7
- And better way to celebrate than with an episode about yet another creature I’ve observed in my backyard (and front yard) – the Botta’s pocket gopher
Growing up in Montana, gophers were everywhere
- Some years there were so many it seemed like you’d step on them just walking outside
- They were considered a nuisance by pretty much everyone, with the common complaint being they dig holes that would break the legs of cattle and horses when stepped in
- Now, I don’t recall ever seeing that happen first hand, or even second hand, but that’s an investigation for another time
Scientifically, these animals are Richardson’s ground squirrels, and looked like small prairie dogs
- But everyone called them gophers
- In fact, I wasn’t aware of their being any other animal called a gopher until I finally got a visual observation of the animal leaving piles of dirt in my yard in southern california and identified it as a pocket gopher
Pocket gophers and ground squirrels are in the same order, but only pocket gophers are true gophers taxonomically speaking
- Will I now stop calling the Richardson’s ground squirrels gophers?
- Probably not
- But it’s cool to know there’s a difference
This is The STEM Sessions Podcast Episode 31 – Is That a Gopher in Your Pocket?
Few dozen times a year, I awake to fresh piles of dirt in my yard
- Though a neighborhood prankster isn’t out of the question, obvious answer is the piles are result of animal activity
- Since it always happened at night, the safe assumption is a nocturnal critter
- A skunk or raccoon digging for grubs perhaps
When I was maintaining a turf grass yard, the piles really bothered me
- Blighted gray islands in a sea of green turf grass
- But the annoyance was never enough to try to get rid of the culprit
- It’s just living its life the best it can in an suburban environment
- So I would rake down the pile, and grass would eventually envelop it
When digging up sprinklers and irrigation lines, I occasionally ran into tunnels
- Roughly the diameter of my fist and much longer than my arm
- Clearly not a skunk or raccoon, they don’t burrow
- Ground squirrels burrow, and plenty of parks in the area have very healthy populations, but never saw any scamper in my yard
- So a mole perhaps?
Over the last two years, I’ve converted my yard from turf grass to native perennials and cultivars and wild flowers
- Process involved a lot of digging
- And my southern California dirt – I’ve not even going to humor it by calling it soil – is like cement
- Digging more than six or seven inches is nearly impossible without a pick axe
Any animal that can burrow through that stuff has my respect
- Plus those tunnels were a big help
- Much easier to dig in areas with tunnels than areas without
- So my attitude was keep on doing what you’re doing whatever you are
Finally, one recent evening while watering a newly installed plants, I saw rummaging in the darkness
- A new pile of dirt was being created
- After several minutes of observation, I captured photos and video of the culprit
According to apps like iNaturalist, the chubby little creature I was looking at was a pocket gopher
- Given my location, most likely a Botta’s pocket gopher
Pocket gophers are rodents (order Rodentia) in the family Geomyidae
- Within the family are seven genera, and across the seven genera there are 41 species
- All species of pocket gophers are new world animals, endemic to North and Central America
Pocket gophers get their name from the fur-lined cheek pockets which they use to carry food and nesting material
- These pockets extend back to the animal’s sholders
- Can be turned inside out to facilitate emptying the contents
Botta’s pocket gopher is found in the genus Thomomys
- These are often called smooth-toothed or western pocket gophers, because their teeth lack grooves common in other species and because they’re found across western north america, from canada to mexico
Botta’s pocket gopher’s full binomial (i.e. scientific) name is Thomomys bottae
- Sometimes called the valley pocket gopher
- Resides in the south west including most of california, arizona, and new mexico, and extending into texas, mexico, utah, colorado, and oregon
Other species within the genus Thomomys include the southern, mountain, northern, Wyoming, and Idaho pocket gophers
- About nine extant species in total
Considered a medium sized gopher
- Typical adults range between seven to 10.5 inches (18-27 cm)
- This includes tail two inches long (5 cm) and fur covered
- Males are about 30% larger weighing between 160-250 g (a third to a half pound) and females weighing 120-200 g (or a quarter to just under half a pound)
Colors range from blonde to dark brown, often matching the color of the soil in which they live
- Do not have a stripe down their back that other species do
Strictly herbivores
- Grasses being a staple of their diet
- Bulbs, tubers, roots also on the menu
- Practice food hording to ensure they have enough to eat during the dormant season
- In agricultural areas, hay crops such as alfalfa
- Water is consumed via food
- Evolved a lower than normal basal metabolic rate to conserve calories for burrowing
Speaking of burrowing, the excavations can extend to a depth of five feet
- Sandy soil, clay soil, loamy meadow soil – doesn’t matter, they dig thru it all
- Home territories of a single adult can cover several thousand sq ft with a several hundred feet of tunnels
- Entrances are found in the piles of dirt, but are often plugged to prevent intrusion and to stabilize temperature and humidity
- This is good means of identification, as entrances to ground squirrel burrows are typically open
Typical burrow system consists of a main tunnel
- Smaller side tunnels are used for food storage and dens
- Other tunnels used to remove soil from the burrow and to expose roots for feeding
- A gopher will travel through the entire burrow system once every 24 hours to inspect it for intruders or damage
Botta’s pocket gophers and others in their genus dig primarily with their teeth
- Gophers in other genera dig with their claws
- Their teeth have evolved to have thicker and harder enamel
- Because teeth are harder, and more durable than claws, Botta’s pocket gopher can dig through a much wider range of soil compositions
This allows them to adapt to many ecosystems
- Sea level to above the tree-line in the Sierra (14000 feet)
- Conifer forests, chaparral, coastal scrub, oak forests, agricultural land
- They avoid areas prone to flooding or with large rivers
- High water table makes tunnel excavation difficult
- Also avoid deserts with very sparse vegetation or extra rocky soil
Despite its range of geography and climates, many conservation groups list Botta’s pocket gopher as a vulnerable species or species of concern primarily due to habitat loss
- On the other hand, California Department of Fish and Game lists them as a nongame mammal
- If they are causing damage to property, they are allowed to be taken using gopher traps and poison bait by the property owner
Botta’s pocket gophers are not strictly nocturnal
- Active throughout the day and night
- However day time activities are typically limited to underground
- Surface activities only at night
- This emersion in darkness may have led to their eyes evolving the ability to see in the ultraviolet in addition to visible light
Face predation from the usual suspects of coyotes, snakes, hawks, owls, bobcats
Botta’s pockett gophers do not hibernate and are active all year long
- Relatively short lived with an average life span of three years
- Also solitary animals, coming together only to mate
- Sexual maturity at one year old
After successful mating, the male moves on and female gestates for 18 days
- Give birth to litters of three or four pups, though larger litters are not uncommon
- Young are born blind and hairless
- Can have up to three or four litters depending on food availability and climate
- As soon as the pups are weened, the female is back to living a solitary life
Pocket gophers can be listed as a pest in agricultural areas
- But outside of agriculture, and even within to an extent, presence of pocket gophers can ultimately help vegetation growth
- Tunnels aerate the soil which in turn improves nutrient absorption and water retention
- Turn over soil by pushing soil from lower depths to the surface which moves minerals
I’ve observed dirt piles for at least six years, which tells me the pocket gophers are successfully reproducing
- Whether this means I have multiple on my lot, or just multiple animals in the immediate area, I can’t say for sure
- I know my neighbors aren’t as keen on the piles of dirt as I am, but I’m going to do my best to convince them to not remove the critters
- Ultimately, I think the pocket gophers are doing more good than harm to our landscaping
- And maybe they’ll grow tired of trying to maintain a pristine turf grass lawn and convert to native plants
- That will help everyone
Thank you for listening to this episode of The STEM Sessions Podcast; researched, written, and produced by Cody Colborn. Shownotes can be found at thestemsessions.com. Feedback and corrections are always welcome.
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Please remember, STEM belongs to everyone. We should not allow it to be siloed or gate-kept by experts, policy makers, or talking heads. Bias is found in every message, so always verify what you read and what you’re told.
Until the next episode, stay curious.
REFERENCES
https://home.nps.gov/prsf/learn/nature/valley-pocket-gopher.htm
https://sacsplash.org/learning-resource/bottas-pocket-gopher/
https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/fseprd534285.pdf
https://file.lacounty.gov/SDSInter/acwm/215274_Gopher_pdf.pdf