Reptile & Amphibian Forums

I've been going through the old posts and I happened across an unsettling trend. Apparently I'm not the only one observing significant population declines. I'm curious as to just how wide spread this phenomenon may be. With that in mind, I created the quick and dirty survey below.

If you are a long time field observers, don't mind sharing and are curious about the subject as well, then please take the time and fill out the questions below for each of your field sites and post it.

I know, it's not very scientific, but that's all right, I just thought it would be interesting for us to compile this data in one place.

Survey Format
a. Species
b. General Location (Closest City will do)
c. Time Span (duration, year to year)
d. Original Population Size
e. Current Population Size
f. Population Change Assumptions
g. Notes

E.G.: Here's my input. I have 5 populations that I'm personally familiar with.

a. Species: Coastal Horned Lizard (P. Coronatum)
b. General Location: Newbury Park, CA
c. Time Span: 1964 - Current
d. Original Population Size: 5 weekly spring & summer
e. Current Population Size: 0 sited in same location over the last 10 years.
f. Population Change Assumptions: Development & Cat predation.
g. Notes: They were thick in the early 60's, almost as common as western fence lizards.
Found many heads found at homes containing female cats.
Within 10 years of 1st housing development, population plummeted to 1-2/year.
Current widespread development placed on prime localities.
Localities and outlying areas are proving to be completely empty since latest housing boom.
Formally large harvester ant populations are gone as well, replaced with widespread Argentine ant population.

a. Species: Coastal Horned Lizard (P. Coronatum)
b. General Location: Thousand Oaks
c. Time Span: 1980 - Current
d. Original Population Size: 1 each spring field trip
e. Current Population Size: 0 sited in same location over the last 5 years.
f. Population Change Assumptions: Significant development in the last 5 years.
g. Notes: They were thick in the 60's, as common as western fence lizards at first.
Found many heads left at housed containing cats.
Within 10 years of 1st housing tract, population dwindled in all nearby areas.
Current widespread development has removed eliminated all previously known localities,
and outlying areas are proving to be completely empty as well.
Large harvester ant population is gone as well, replaced with widespread Argentine ant population.

a. Species: Desert Horned Lizard (P. Platyrhinos)
b. General Location: Palmdale
c. Time Span: 1978 - Current
d. Original Population Size: 4-5 every spring trip in 70's to 80's
e. Current Population Size: 0 now
f. Population Change Assumptions: Development. All dense populations are now houses. g. Notes: Although this location was well known too many local hobbyists, significant decline did not occur until development took place.

a. Species: Desert Horned Lizard (P. Platyrhinos)
b. General Location:Mojave
c. Time Span:1978 - Current
d. Original Population Size: 4-5 every spring.
e. Current Population Size: 5-10 every spring.
f. Population Change Assumptions: Recent visits showed substantial, unexpected population increase. Suspect migration due to nearby development.
g. Notes: This localized population went through a significant decline as RV's (mostly motorcyclists) started using the area in mid to late 90's.
However, there has been a recent resurgence in the population, but now there's a very high level of development in the nearby area (~ 1mile away).

a. Species: Desert Horned Lizard (P. Platyrhinos)
b. General Location: Lucerne Valley
c. Time Span: 1990 - Current
d. Original Population Size: 2-3 every spring.
e. Current Population Size: 1- every spring.
f. Population Change Assumptions: Hobbyists informed of population, potential collecting issues. Obvious increase in RV use present. Localized drought also apparent.
g. Notes: This localized population appears cyclical. Wetter years seem to produce higher pop's for 1-2 years. Obvious drought present as well as motorcyclist have invaded locality.

Interesting Roger.

I have not kept tabs by numbers on the HL's I observe but I have a few notes to add.

The CHL populations I observe on a regular basis are not in developed areas, far from it. They are also in drier climes than Newberry Park. So I have seen no declines at all and no invasive ant species (I believe due to the drier habitat).
I did walk around in Moorpark and found that almost all of the P. californicus nests were under serious attack by the argentine ants.
So I have a feeling that HL's in moist habitat, with serious development are going to continue to decline, probably to extinction, while the HL's in drier desert habitat without so much pressure from development will continue to thrive.
I don't know what you could do short of getting rid of the people and the ants to stabilize them. I think it's just a fact of life that we will have to accept for these areas.
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The San Diego Horned Lizards are in very low numbers or extinct now everywhere within a few miles of the coast in San Diego County except for possibly parts of Camp Pendleton which is undeveloped. I found three this year, two in the mountain east of San Pasqual and one near a trailhead to Eagle Mountain(which had been burnt by the Cedar Fire), all somewhat remote areas. P. Californicus now seems to be absent to most coastal habitats with under one square mile of open space, expecially where there are invasive non-native plants in which Argentinan Ants easily completely take over. Where they still exist there may be isolated pockets where there are horned lizard populations if they are undisturbed.

I used to work at an orchard on a hill in Carlsbad where there were horned lizards in the 70's. When I was a kid almost 50 years ago they were very common in the fields adjacent to Big Springs Rd in Riverside between UCR and the Box Springs Mountains. The habitats where they used to be very common have been either developed, altered, or their food supply has been eliminated. Domestic preditors and overcollecting also helped in their demise from these areas, once their populations becomes marginal. They aren't resiliant like fence lizards and side-blotched lizards are, and once they're gone you can't expect them to return.

Decades of uncontrolled development in Southern California have resulted in a holocast for many native animal populations and horned lizards have fared much worse than most.

It is actually staggering what has happened in California over the last 30 years. It's a good thing the national forests are set aside or there would be no place for these guys eventually.

It's a lesson for the younger folks and all of us. Hold onto that national forest at all cost!
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Phrynosoma.Org
Phrynosoma.Com

Yup...seen it myself here in Southern CA. U.S. human population hit 100m in ~1916, 200m in ~1967, and the nightly news just announced we hit 300m today. Projections are that the US will hit 400m within the next 50 years and just about each of the southwestern states are predicted to double in population by the year 2050. So where will the wild HL's populations be at that time? And given the fact that along with humans comes Fire Ants and Argentine Ants, where will the Harvester Ants population be at that time? Get's you thinking a little bit, don't it.

Yes it does indeed. I have to wonder how they figure those projections though. There is a point of diminishing returns. When the west gets to a point of being way overpriced and overcrowded there will surely be folks moving back to places with a better quality of life. I moved from Cali two years ago and was just considering going back from AZ. But after a weekend trip to visit we quickly changed our minds. Too many folks and brown air. It's just no fun anymore. LOL
Arizona is Cali 30 or 40 years ago. I'm sure it'll happen here someday, but for a while to come it should be a nice place to live.
So I did my part to depopulate Cali.
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Phrynosoma.Org
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Good point. Always question information not supported with scientific data. The popoulation predictions are really just educated guesses. Unfortunately, the predictions I've been reviewing have AZ as one of the states leading the way in population growth over the next 30 - 50 years, just behind NV and in front of Texas, Utah and CA...all of which are showing up in the top 10 for predicted growth. The warning signs are not good.

Where in AZ are you? I'm thinking of leaving CA as well, considering Southern UT/Northern AZ, somewhere in the middle of the Grand Canyon, Zion, Lake Powel, Cedar city & Vegas. You anywhere near this area? Got any suggestions?

Thanks,
Roger

Hey Roger,
AZ has a long way to go to catch up with Cali at 5 million folks. I am 40 miles east of Phoenix but I applaud your choice of the north country. It's very nice up that way depending on what you want.
A few of the places we really like are Sedona area, Payson and Pinetop / Lake Side. But we are pretty happy where we are too, being close to 4 lakes and lots of herps and far enough from the city to enjoy the peace.
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