USGS Scientists find abundance of reptiles and amphibians living in El Monte Valley
Dr. Jonathan Q. Richmond, wildlife geneticist with the United States Geological Survey (USGS) led the first ever-comprehensive study on reptiles and amphibians living in the El Monte Valley. The Endangered Habitats League and the El Monte Nature Preserve LLC funded the one-year study by the U.S. Geological Survey. Two entities are currently involved as partners in the sand mining project proposed for the El Monte Valley. El Monte Nature Preserve LLC, formerly known as El Capitan Golf Course, LLC, is purchasing the land from Helix Water District, while the Endangered Habitats League led by Michael Beck, environmentalist and also chairman of the San Diego Planning Commission, would be responsible for restoring couple of hundred acres of sand pit into a riparian habitat after the mining, that may be completed in few decades.
The battle for the valley is almost 20 years old and the community is concerned that Beck and his sand mining partners will win this time, based on his claim that El Monte Valley is a deserted place with no significant wildlife habitat to deserve conservation, thus justifying digging a crater as deep as a 10-story high building and as large as 300-500 acres. That is twice as tall as Qualcomm stadium and as long as the Coronado Bridge.
The recent study completed from June 2015 until May 2016 by Richmond and his team of scientists proves the exact the opposite. The team captured 1,208 reptiles and amphibians, which shows the wide diversity of fauna in the San Diego river bottom. The valley is partially a highly disturbed alluvial soil by the illegal sand mining done here 20 years ago by the same company, Bill Adams’ El Monte Nature Preserve LLC. which was never held accountable to restore the place. The study concludes that this rare coastal shrub habitat is hosting a surprising number of thriving reptiles and amphibians, some of them being sensitive species. Two species found in the valley are covered in the San Diego Multiple Species Conservation Program and 10 are listed as species of special concern by the California Department of Fish and Wildlife. Richmond believes that “the high level of species richness and diversity was surprising, given that the study was conducted during the 5th year of exceptional drought in the southwestern United States.”
The question on many minds is if this scientific study is going to be used as part of the Environmental Impact Report (EIR), expected to be completed by the end of this year in conjunction to the sand mining permit application.
Mr. Richmond, is this study related to the controversial sand mining project in the El Monte Valley?
Richmond: “The USGS has no role in that endeavor, beyond our study's implications for the project. What people choose to do with the information is up to them - our job is to simply provide accurate and thorough information. This study was not designed to address the impacts of the sand mining project – the goal was to provide an up-to-date characterization of the species richness and diversity in the valley.”
“Survey work in the valley (the peer-reviewed scientific publication due out soon in the Southwestern Naturalist_www.bioone.org/toc/swna/61/2). Developed by the five authors of the study, all of the work was conducted solely by USGS employees and volunteers with North American Field Herping Association (NAFHA_www.nafha.org/).”
“We designed the surveys in such a way that they are easily repeatable and verifiable by anyone choosing to do so, and of course we stand behind the work 100 percent. The authors of the study are Jonathan Richmond, Carlton Rochester, Nathan Smith, Jeff Nordland, and Robert Fisher.
How long did it take you and your team to complete the study?
Richmond: “Originally it was supposed to be for six months, but then it was extended for a full year. If you want to get a really good picture of what’s out there, you need to survey for at least a full year. Ideally we would want to survey across multiple years given the annual variability in climate these days, and we’re currently searching for funding opportunities to continue the work.”
Who decided to extend it for a year?
Richmond: “Robert Fisher, my supervisor at the USGS. That was a smart thinking because we would have missed quite a few species had we not sampled throughout the year.”
Such as what?
Richmond: “We would have missed the rarer species. Reptiles and amphibians are most active during the breeding season, which typically extends from early March through May. Animals are more active when they’re searching for mates, which make them easier to observe in the wild. Activity also picks up in the spring once we get some rainfall, then it tends to trickle down during summer when it gets hot and dry. Initially, we intended to survey the valley from June to November 2015 – had we limited the study to just those 6 months, we would have missed the spring entirely.”
“In the end, the study lasted for 12 months and we used a variety of techniques to conduct the surveys. These included fence line snake trapping, cover boards arrays, walking transects, and road cruising. The paper is being published in a peer reviewed scientific journal, which means that other scientists have critically reviewed the work to ensure high quality science. The USGS also conducts its own internal review, so we can assure readers that the work has been thoroughly vetted. Once the paper has a digital object identifier with the journal, it will be publicly available for everyone to read.”
What are your findings in the valley?
Richmond: “We detected twenty-seven different reptile and amphibian species. There were 13 different snake species, 11 lizard species, and three species of amphibians. Greater numbers of amphibian species might be exist further east in the valley toward the dam, but that was outside of our study area. If we’re able to get continued funding, we’d really like to sample some of the areas that are east of Hazy Meadow lane toward the dam.”
What amphibians did you capture?
Richmond: “The most common amphibian species was the Western toad, followed by the spadefoot. Spadefoots have been traditionally recognized as toads, but they actually belong to a separate evolutionary lineage with respect to the ‘true’ toads, like the western toad. We detected the third species, the Pacific tree frog, only by its call, which is very conspicuous during the spring, especially after rain. This species was calling on the north side of the valley on private property that we did not have access too, but the call is so conspicuous that we knew exactly what it was when we were doing night surveys.”
“We found more species of snakes than lizards. The most common snake was the Southern Pacific rattlesnake; the second most common was the California Glossy snake. There were four species represented by single individuals only. This could be due to the drought, but that are numerous other factors that could also be influencing their low abundance.”
What about the lizards, any rare species?
Richmond: “There are no rare species, but there are several that are of conservation concern, mainly because of habitat loss and or because their distributions are small to begin with. The most common lizard species were the orange-throated whiptail, the side-blotched lizard, and the western fence lizard. We also captured Blainville’s horned lizard, the California legless lizard, which indeed is a lizard, but it has no legs and it looks a lot like a snake, two species of skinks (the western skink and the Gilbert’s skinks), the San Diego banded gecko, and a few others.”
“The reptile community in El Monte Valley is uneven, which it means that there are a few very common species that co-exist with others that are far less common. In other words, you don’t have equal abundance of all species.”
When you mention very rare species, you mean very rare for the valley and not endangered species in general.
Richmond: “Correct, rare for the valley.”
Can you please name few of the less common species of snakes you caught in the valley?
Richmond: “The less common species were the ringneck snake, the black headed snake, the San Diego night snake, and the patch-nosed snake. We also found only three red diamond rattlesnakes, one was a juvenile and two were dead on the road. The red diamond was not nearly as common as the Western Pacific rattlesnake.”
What can you tell us about the diversity of the species in the valley?
Richmond: “Well, there was a remarkable diversity for the condition of the valley. There are some areas that retain intact coastal scrub, but much of the vegetation and landscape is highly disturbed. There are lots of invasive weeds and grasses, and large stands of invasive tamarisk and eucalyptus. So, it was surprising to us that the valley still supports a high number of species. The alluvial sands in El Monte Valley are now rare in coastal San Diego County, largely because of the extensive urbanization. Historically, sand mining is also the most lucrative form of mining in the county. This loose, alluvial soil is simply a rare constituent of what little remaining open habitat there is in coastal San Diego. Many of the species in El Monte Valley, like the California legless lizard, Blainville’s horned lizard, and the glossy snake depend on these loose soils for survival.”
How many glossy snakes were you and your team able to find?
Richmond: “We caught 23, 20 of which were unique individuals and three were recaptures of the same individuals. Any glossy snakes we captured, we took small tissue samples for an ongoing genetic study in our lab. This allowed us to tell whether we had recaptured the same individuals of this particular species. For all other species, we didn’t mark the individuals we captured, so it’s possible that some of our total number of captures for different species is slightly inflated. We discuss this and several other caveats about out sampling techniques in the paper.”
Okay, and how is that compared with an average habitat for glossy snakes?
Richmond: “It’s a lot. USGS has been doing similar surveying work across San Diego County since the mid-90s. Of 52,000 species observations over that 20-year time period, approximately 3700 represent snakes of different species. Of those 3700, only one was of a California glossy snake, until this study in El Monte Valley. It’s crazy! That previous record was from Camp Pendleton. So, it’s quite remarkable that we turned up 20 glossies in just one year, in addition to being at the end of a five-year drought.”
That is indeed incredible, congratulations for your hard work.
Richmond: “Based on literature dated back in the 40’s, glossy snakes were common all the way up to the coast. There are interesting stories about them being captured on top of the cliffs in La Jolla. Carlsbad, Del Mar and in other places where you would never see them these days.”
Then it looks like glossy snakes are now thriving in the El Monte Valley.
Richmond: “It’s difficult to say whether they are thriving. They are certainly there in high numbers compared to other areas west of the Peninsular Range in coastal San Diego. We know it’s a reproducing population because we captured both juvenile and adult individuals.”
Is the El Monte Valley a specific habitat for the glossy snakes? Would the glossy snake be able to survive up on the rocky hills and mountains surrounding the river bottom if the current habitat would be severely disturbed?
Richmond: “This habitat is not specific to glossy snakes. Clearly, a variety of species occupy the habitat in El Monte Valley. Glossy snakes generally avoid steep slopes, but they often occur in association with big granite outcrops like ones you see on the hillsides in EMV. When those big granite boulders degrade through erosion, they tend to form loose sandy soil, which is what the glossies and a few of the other species in the valley really like. It's doubtful that they would take to the hillsides in EMV because the slopes are so steep - that nice, open sandy river valley is the reason why they're there.”
What is the native habitat in the valley? Is it specific to reptiles and amphibians?
Richmond: “The general term would be ‘scrub habitat’ of which the alluvial sand is a main constituent. In other words, the sand is a key element of that habitat. Scrub is not specific to reptiles and amphibians.”
I wanted to confirm with you that you also found horny lizards in the valley and I was curious how many, please? The locals told me that there use to be many of them in the valley and I was curious what would be the possible cause for the decrease in population.
Richmond: “Yes, they’re actually called horned lizards. The species that occurs in the valley is Blainville’s horned lizard and is now state listed as a species of special concern. We captured both juveniles and adults. The species is declining range wide, mainly due to habitat loss and the presence of an invasive ant species, the Argentine ant. The Argentine ant displaces native harvester ants, which is the main food resource for the horned lizard. Horned lizards also avoid the thick, non-native and invasive grasses that occur throughout much of the El Monte Valley floor. So, I would say that the two biggest threats in El Monte Valley are the invasive grasses and the Argentine ants.”
People are talking about the red-legged frog being seen in the valley. Is that rumor accurate?
Richmond: “No, unfortunately it’s not accurate. They are probably seeing invasive bullfrogs and mistaking them for California red-legged frogs. We’ve heard that there are bullfrogs toward the dam at the east end of the valley. The CA red-legged frog is extirpated from San Diego County. The closest living relatives, based on genetics, are in the Sierra San Pedro Martir in Baja California. We are currently engaging with Mexican researchers to protect those populations and to possibly re-introduce them to certain parts of San Diego County, but we're still a ways off from being able to do that.”
How did you divide the land to collect your sampling?
Richmond: “We divided our sampling into five sections that stretched from the west side of the valley near Hansen Pond over to the east side near Hazy Meadow Lane. We wanted to look at whether diversity varies depending on location within the valley. The question was whether certain sections of the valley are better able to support certain species or higher numbers of individuals than other areas.”
What are your conclusions to these questions?
Richmond: “Different parts of the valley support a different numbers and types of species. Although for lizards and snakes, we found that a large proportion of species were present in four or more of the sampling sections, suggesting that these species occupy a considerable portion of the valley floor.”
Did you and your team find any species that are more sensitive to a change in habitat in the valley?
Richmond: “Yes, some species in the valley are more sensitive to disturbed habitat than others. Some species are actually quite tolerant of disturbance, like the western fence lizard and southern alligator lizard.”
Could you please name some of the more sensitive species?
Richmond: “Sure, the red diamond rattlesnake, the long-nosed snake, and the coast patch-nose snake are a few examples. The glossy snake can actually tolerate pretty disturbed habitat as long as there is a matrix of scrub with loose soils and an abundance of lizard prey. They mostly eat lizards and small rodent species – in fact the two most common lizard species in El Monte Valley constitute the main diet of glossy snakes, so even the common species are worthy conservation targets because they provide valuable food resources for other taxa.”
What kind of disturbances are we actually talking about?
Richmond: “I am mainly talking about non-native vegetation, particularly the thick grasses, weeds and tamarisk that are now out in the valley, the presence of roads, off-highway vehicle use, trash – all of that would constitute disturbance, but mostly habitat destruction.”
Did you say destruction of the habitat?
Richmond: “Right. The valley has a long history of agricultural land conversion, which resulted in the removal of large swaths of native vegetation. There is human foot and horse traffic, off-highway vehicle use, and there was a failed golf course development in the early 2000s that left giant pits in the ground towards the east end of the study area. The pits have steep banks and the bases are now infiltrated with non-native weeds and grasses – we didn’t find any reptiles or amphibians in them at any point during the survey.”
Is this study going to be included in the Environmental Impact Report that has to be done for the sand mining project in the valley?
Richmond: “All I can say is that it wasn’t intended as an environmental impact study, but because it provides a current characterization of the reptile and amphibian community within the valley, it seems likely that it would somehow play into it. We (i.e. the USGS) have never been told that it will be a part of an official EIR.”