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.

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