Category Archives: trails|smmc open space

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September & October are Tarantula Months!

first published & last updated
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Tarantula at Ahmanson Ranch

Updated October 28, 2024.

Since 2005 these are the dates I’ve photographed a tarantula at Ahmanson Ranch (Upper Las Virgenes Canyon Open Space Preserve). The dates are sorted by month and day.

September 05 (2012)
September 08 (2006)
September 13 (2005)
September 19 (2007)
September 15 (2009)
October 3 (2012)
October 9 (2012)
October 11 (2006)
October 12 (2011)
October 12 (2023)
October 17 (2012) (2)
October 22 (2020)
October 23 (2013)
October 28 (2024)

If I see a tarantula, I always try to photograph it. Over the years there may be one or two that scurried into the grass and brush before I could snap a photo.

I did not see a tarantula at Ahmanson during the period 2014 – 2019. There was a five year drought in 2011 – 2015 and the Woolsey Fire was in November 2018. The routes and frequency I run at Ahmanson have not changed appreciably since 2005 .

Autumn is when maturing male tarantulas (Aphonopelma spp.) wander about in search of a mate.

Tarantula in East Las Virgenes Canyon
Tarantula in East Las Virgenes Canyon

The title photograph is from a run on September 5, 2012. The raised abdomen is a defensive posture. Tarantulas will scrape their abdomen with their bristly rear legs, launching irritating (urticating) barbed hairs into the air. Most tarantulas I’ve encountered this time of year do not react defensively — they’re just interested in finding a mate.

A search on iNaturalist shows a few observations ( 2 to 6) of tarantulas in the Ahmanson area each year since 2020.

Some related posts: Tarantula Time, Sting of the Tarantula Hawk, Tarantula Hawk

nature, nature|weather, photography, photography|landscape, trails, trails|smmc open space, weather, weather|el nino, weather|la nina, weather|southern california

Dowsing for Rain: The 2013-14 Southern California Winter Precipitation Outlook

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Rocky Peak Road near its junction with the Chumash Trail

Updated October 17, 2013.

As I started up the Chumash Trail, a patchwork of clouds filled the sky, and the fresh smell of a recent shower filled my lungs. A strong and unseasonably cold low pressure system was producing the first widespread rainfall of Southern California’s 2013-14 rain season.

I hoped there would be another shower during my run. The plants and animals needed it and I needed it. It had been many months since I had run in the rain on a local trail.

As I worked up the trail I thought about how dry it had been. Downtown Los Angeles’ 2012-13 water year (Jul 1 – Jun 30) was the sixth driest on record. Rainfall in Los Angeles since January 1 has been about 25% of normal. The 2012-13 Sierra snowpack was one of the worst on record.

Will this rain and snow season be any better? For months I’ve been monitoring climate data and forecasts looking for something on which to base a 2013-14 Winter Outlook. Historically, ENSO has been the big dog in Southern California rain season weather with El Nino conditions generally producing wetter weather and La Nina conditions generally drier.

But ENSO conditions are currently Neutral and are expected to remain so through the end of the year. Most climate models forecast there will be slow warming of SSTs in the equatorial Pacific (NINO 3.4 region) over the next several months, but at this time of the year it would be very unusual to have substantial warming. The CPC/IRI ENSO Forecasts from IRI’s October Quick Look indicate the probability of an El Nino developing before the end of the year is less than 20% — and 20% seems high.

One computer model that at times has been forecasting above average precipitation this Winter in Southern California is the Climate Forecast System version 2 (CFSv2). The CFSv2 is fully coupled ocean-atmosphere-land-sea ice model used to forecast parameters such as sea surface temperature, temperature and precipitation rate. While skillful at predicting tropical SSTs, the CFSv2 generally performs very poorly when forecasting precipitation over land, so forecasts such as this one for Dec-Jan-Feb must be viewed somewhat skeptically.

Another glass half-full observation is that the Madden-Julian Oscillation (MJO) has been relatively active this year and if this activity continues it provides recurring opportunities for enhanced U.S. West Coast precipitation. The downside is that it can result in periods of dry weather as well.

With the ocean and atmosphere neutral there’s just not much on which to base a rain season forecast. According to the Climate Prediction Center, the current winter precipitation outlook for most of Southern California calls for an equal chance of below average, average, or above average rainfall. I know — that’s no help at all — you might as well flip a three-sided coin!

Update October 17, 2013. The Climate Prediction Center released its updated U.S. Dec-Jan-Feb Precipitation Outlook today. The outlook now indicates an equal chance of below average, average, or above average precipitation for all of Southern California. The October CPC outlook is usually the basis for the initial official NOAA U.S. Winter Outlook.

The title photo is of Rocky Peak Road, near its junction with the Chumash Trail. Here’s a larger version of the panorama.

nature, nature|wildlife, photography, photography|wildlife, trails, trails|smmc open space

Acorn Woodpeckers at Ahmanson Ranch

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Acorn Woodpeckers at Ahmanson Ranch

The health of an ecosystem can be measured by the sounds it produces. The more full the spectrum (and the more niches filled) the healthier the habitat.



One of the spectrum-filling sounds you’ll hear at Ahmanson Ranch (now Upper Las Virgenes Canyon Open Space Preserve) is the squawking and talking of acorn woodpeckers in the valley oaks and coast live oaks.

Acorn woodpeckers have a surprisingly complex social structure, a part of which is related to the maintenance and protection of acorn granaries within their territory.

Despite last rain season’s meager rainfall, the valley oaks at Ahmanson Ranch have managed to produce a decent crop of acorns this Fall, so much of the banter in the oaks overhead must be about that!

For more info about these birds see Cornell Lab’s All About Birds and the Forest Service’s Fire Effects Information System.

nature, nature|wildlife, photography, photography|black & white, running, trails, trails|smmc open space

Missing Snakes at Ahmanson Ranch

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Legend has it that St. Patrick chased all the snakes from Ireland, and while there have been no reports of the 5th Century cleric being sighted at Ahmanson Ranch, I don’t recall a Spring and Summer when I’ve seen so few snakes in the 3,000 acre preserve.

I’ve run at Ahmanson Ranch — now Upper Las Virgenes Canyon Open Space Preserve — more than a decade. I generally run at Ahmanson a few times a week and have become very familiar with the area’s plants and wildlife.

So far this year I’ve seen no mature rattlesnakes and only one gopher snake at Ahmanson. I’ve seen a couple of baby rattlesnakes and a handful of tracks, but that’s it. In some years I’ve counted more than a dozen snake tracks during one 7 mile run.

The reduction in the snake population is likely related to back-to back years with low rainfall. This year Downtown Los Angeles has recorded only 2.72 inches of rain since January 1. That’s a deficit of nearly 8 inches and about 25% of the normal amount of rainfall.

The reduced rainfall not only reduces the population of rodents, reptiles and other prey animals sought by snakes, but also increases the likelihood snakes will be preyed upon by animals higher on the food chain. Snakes, including rattlesnakes, are eaten by a long list of birds and mammals, and may also be preyed upon by other snakes. Humans also kill a large number of snakes.

The title photograph is the track of a Southern Pacific rattlesnake.  The snake was moving from the upper left of the photo to the lower right.

Some related posts: Big Southern Pacific Rattlesnake at Ahmanson Ranch, Southern Pacific Rattlesnake