Robert Jan "Roy" van de Hoek
El Camino College
2005 and 2006
Few areas of comparable size in the immediate coastal region of California are hosts to such a great variety of life forms as have been found at El Segundo Sand Dunes. The present paper, a result of observations carried on in this general region intermittently over a long period of time, beginning in August, 1931, deals with the three species of amphibians and sixteen species of reptiles known to occur in the vicinity of the dunes.
Certain biological principles governing animal distribution are readily illustrated in the herpetological fauna of the area. Amphibians, by their very nature being largely dependent upon the presence of more or less permanent pools or streams of freshwater, are consequently poorly represented in the dune area. Indeed, were it not for the occurrence of nearby Ballona Creek, at least one, and probably two, of the species (the Hyla primarily, and the Bufo) would not be found in this area at all. An abundance of decaying leaves, rotting boards, and piles of dead brush, serving as they do to conserve moisture, adequately provides the necessary dampness for Batrachoseps. Without doubt, the influence of the sea in keeping the area moist through the incidence of fog and heavy dewfall is an important factor in producing the amount of humidity required for existence of all three amphibian species in this area.
Conditions in the dunes are especially favorable for most of the reptilian species found there. The sandy nature of the soil makes the area particularly adaptable to such species as Uta, Sceloporus, Phrynosoma, and Anniella. The presence of grassy areas with convenient hiding places under dead brush, boards, and debris is an attraction to such forms as Gerrhonotus, Eumeces, and Diadophus. The brushland and heavily weed-grown portions of the dune region provide suitable cover for Masticophis, Coluber, Pituophis, and Lampropeltis. Here again, as with the amphibians, Ballona Creek exerts its influence in providing at least part of the habitat requirements for some of the reptiles. Particularly referred to are Thamnophis (two species) and Clemmys. Fortunately, because of the danger that might otherwise be presented to picknickers and school children in this locale, the lack of large rocky areas in the dune region probably accounts for the rarity of Crotalus here. At least two of the forms herein included (Lichanura and Clemmys) may be regarded as "accidentals" until such time when further records of them from this area may be available.
An adequate food supply for this herpetological assemblage is ever present in the form of abundance of rodent life for the larger snakes and veritable legions of insects for the smaller snakes, the lizards, and the amphibians.
In the pages that follow, specific accounts are given of the occurrence of cold-blooded vertebrates as found in the course of this survey. In addition to the writer, the members of the sand dunes survey group who have contributed notes and collected specimens of the species herein reported are: Drs. John A. Comstock, W. Dwight Pierce, and Robert L. Rutherford, Miss Frances L. Cramer, Mrs. Dorothy Pool, and Messrs. Chris Henne, Lloyd M. Martin, Gus F. Auguston, Karl Snyder, and J. Ernest Lewis. To all of these fine field workers the writer wishes to express his sincere appreciation for their helpful cooperation and their respective contributions to the present study.
Their chief enemies are snakes, notably garter snakes, ring-necked snakes, and racers. Alligator lizards and shrikes, as well as certain birds, are also known to prey on them.
The food consists of the smallest insects visible to the naked eye.
As may be implied from the racial name, halophilus, this subspecies is quite tolerant of saline conditions in the environment, whereas most amphibians are not so adapted. On February 15, 1938, one was found hiding in sand at the edge of the strand less than thirty yards from the high tide line of the ocean. Here the sand was considerably moist from the saline spray of waves pounding on the shore.
Experiments in the laboratory reveal the toad to be entirely insectivorous.
Enemies of the toad are few in the sand dune area. Because of the presence of dermal poison glands, they are ensured safety from molestation by mammals through the factor of being unpalatable to the mammalian tongue. Young toads are sometimes preyed upon by great blue herons, sparrow hawks, roadrunners, garter snakes, gopher snakes, king snakes, racers, and alligator lizards.
Presumably representatives of this species wander into the sand dune area from Ballona Creek, in the vicinity of Playa del Rey, the nearest body of water suitable for tree-toads to complete their early metamorphic stages in.
Their chief enemies in the sand dune area are alligator lizards, racers, garter snakes, great blue herons, roadrunners, and shrikes.
From our observations the food comprises insects exclusively.
Individuals are frequently found in summer, sunning themselves on the larger limbs of shrubs, such as coyote brush (Baccharis pilularis), lemonade-berry sumac (Rhus integrifolia), or wild buckwheat (Eriogonum fasciculatum). Often they may be observed in the performance of the curious though characteristic "push-up exercise", which may serve as a temperature regulation act. They are apparently exclusively insectivorous.
We have no definite evidence of species preying upon this lizard in the sand dune region, but suspect the larger snakes, sparrow hawk, burrowing owl, roadrunner, and shrike may be classed as enemies.
Often individuals are found with all but their heads covered with sand, lying in wait for their arthropod prey which they pick off the surface of the ground with rapid thrusts of their sticky tongues. The habit of covering the body with sand is also believed to be a protective measure to escape detection during the heat of midday.
Captive individuals have been observed in the process of burying themselves in this manner. It is accomplished by rapid undulatory sideward movements of the flattened body, a few hurried kicks of loose sand thrown over the back, followed by downward thrusts of the legs. Slight up-and-down motions arrange the sand in such a way as to give it the appearance of having been undisturbed. When the body is thus completely hidden from view, the head resembles a small jagged rock, or burr, lying on the ground.
Evidence that the shrike may be regarded as an enemy of this lizard is afforded by an immature Phrynosoma found impaled on a pointed branch of a dead California croton (Croton californicus), October 26, 1939. Other predators known to feed on horned lizards are: sparrow hawks, barn owl, burrowing owl, roadrunner, badger, and gray fox. Some snakes probably also prey on them, though we have no supporting evidence for this belief from the sand dune survey.
The food comprises insects, chiefly ants - though many other insect types are fed upon.
Captive specimens fed readily on sow-bugs, mealy worms, wire-worms, ants and small tenebrionid beetles. Also one large individual devoured a large Batrachoseps and a small Uta placed in its cage one afternoon, and swallowed two small footless lizards on another occasion.
Kingsnakes, great blue herons, sparrow hawks, and road-runners appear to be their chief enemies.
Individuals retained in captivity refused to eat and seldom lived more than two months. In their normal habitat the food is apparently insects.
Its enemies are unknown, though, as mentioned above, a captive alligator lizard devoured two small Anniellas one day.
This is a most surprising record, as the rosy boa is normally an inhabitant of brush-covered valleys and mountains. It is possible that the individual was an escape from some small boy's menagerie in the neighborhood, yet there is a nearby coastal record from Topanga Canyon in the Santa Monica Mountains and it is not impossible to believe that the brush-covered meadow slope of the El Segundo sand dunes may be a suitable habitat for this species, which never appears to be abundant wherever found.
While the ring-necked snake is chiefly insectivorous in diet, it is also known to feed on Batrachoseps and young lizards of small size, killing the latter by contriction. On occasion, Diadophis may be cannibalistic, feeding on its own kind, a few examples of this nature being already on record.
The largest specimen taken on the dunes to date measured 17 inches long. It was found April 2, 1939, in the dune complex on top of the largest dune near a patch of tuna cactus (Opuntia littoralis). A perfect cast skin found July 11, 1939, under a clump of tuna cactus in the fore-dune area measured 14 inches in length. Larger individuals are on record from other regions in southern California.
We have no data on enemies of this snake in the sand dunes region.
Racers are known to feed on salamanders, young toads, tree-frogs, small lizards, young birds and bird eggs, and small mice.
A specimen captured September 4, 1931, in the meadow near the base of the dune, measured five feet seven inches long from the tip of its snout to tip of tail. Dissection of the alimentary canal of this individual revealed that it had swallowed 3 adult and 4 immature pocket gophers, 1 harvest mouse, and 2 meadow mice shortly before it was collected. Another gopher snake taken April 10, 1932, on the meadow slope of the dune, contained 1 silky-haired pocket mouse, 1 coarse-haired pocket mouse, 1 parasitic mouse, 4 white-footed mice, and 2 harvest mice. It was somewhat smaller than the September-taken specimen, measuring only four feet ten inches in length.
Chief enemy of this snake is man, the exterminator.
This species feeds on tadpoles, young toads, tree-toads, and small fish. Occasionally it may feed on small lizards, harvest mice, pocket mice, and shrews.
This is a thoroughly destructive species with few, if any, redeeming characteristics. Its food comprises earthworms, tadpoles, salamanders, toads, frogs, and fish.
Bogert (this bulletin, vol. 29, Jan-Apr. 1930, p. 12) records a specimen from Ballona Creek which gave birth to 16 young on September 8, 1928.
As regards food habits, the three amphibians and five of the reptiles are apparently exclusively insectivorous. Of the remaining reptiles, one may be classed as omnivorous and the rest feed chiefly on vertebrates and occasionally on insects. The carnivorous habits of at least four of the reptiles warrants their being classed as beneficial to man as aids in maintaining a check on the increase of harmful rodents. The same is true of the exclusively insectivorous species as checks on the insects. Two of the reptilian species may be classed as harmful, one because of its danger to man through its poisonous bite and the other because its food habits cause it to prey on beneficial species. Fortunately, these two types are comparatively rare in the area. The remainder may be classed as harmless in so far as man's interests are concerned.
This Afterword to the report by Jack von Bloeker in this second edition, is revised only by this opening paragraph and a subsequent second paragraph. The first item that I would like to report to the readers and users of this essay is how many times the term "Ballona Creek" appears in the von Bloeker report of 1942. I have tablulated 8 times that "Ballona Creek" is stated. If I include one entry that stated "sloughs of the Playa del Rey region" to this tabulation, then the total is 9 times. Interestingly, the term "slough" is mentioned 2 times. And similarly, the term "Playa del Rey" is mentioned 5 times. In one instance, "Playa del Rey" is mentioned in a single phrase with "salt marsh" which appeared as follows: "Playa del Rey salt marsh." Why did Jack von Bloeker use the phrases of "BALLONA CREEK - SLOUGHS - SALT MARSH - PLAYA DEL REY" for a total of 17 times on nearly every page of his 9 page report? Wasn't his report supposed to be about "dunes" as indicated by the title of his article ? In von Bloeker's "Introduction" and again in his "Summary" he also used the phrase "BALLONA CREEK" on 2 occasions. It would seem that Jack von Bloeker could have included the term "BALLONA CREEK" or "PLAYA DEL REY" together with "Dunes" in the title of his report, so much so, that we may wonder why he unintentionally mistitled his article by stating it was solely about the "Dunes." As a careful reader or researcher reads Jack von Bloeker's report it becomes clear that he wanted to teach and share with us the linkages between sand dunes, river sloughs, salt marshes, reed-bed marshes, and salt-water lagoons.
Interestingly, approximately 40 years elapsed before the herpetofauna of Ballona Creek and its wetlands are analyzed again by two young herpetologists. These two herpetologists analyzed the herpetofauna of the open spaces of the Ballona Wetlands, for a chapter of a lengthy report, compiled by the young Ralph Schreiber (1981), and entitled BIOTA OF THE BALLONA REGION. Interestingly, this report completely omitted any reference to Jack von Bloeker and his significant contribution to the biological science and natural history at Ballona. Was it intentional or an innocent accident that there was no reference to the von Bloeker report in the Schreiber report? In any regard, it is hoped that this "Afterword" by this writer is helpful as a scientific natural history essay for understanding the Ballona Wetlands. This essay, together with my compilation and editing of the Jack von Bloeker report for the internet hopefully remedies this oversight of 25 years ago in the Schreiber report. I hope also that the interested public and governmental agency representatives, but particulalry environmentalists and and avocational naturalists will now be able to easily access the von Bloeker report not only for educational purposes and environmental activist guidance, but also for conservation - preservation - restoration (CPR) purposes of the newly acquired state land at the Ballona Wetlands in Playa del Rey, which is currently undergoing a radical restoration planning process by the state of California.
Ballona (Bayona) Valley with its reptiles and amphibians makes up a fascinating urban ecology, which is complex and not easy to communicate to the lay person. I would like to present this complexity via two examples from the herpetology world. These two examples are the California Legless Lizard and the Rattlesnake.
The Rattlesnake was discussed as an ecological component of the fauna of Playa del Rey by Jack Von Bloeker in his report, but it was discussed as being very rare. Thus, the observation by this writer (2005) of a Rattlesnake, and subsequently two conversations with two citizens (2005) is significant. This interesting situation became clear, once I had observed with my own eyes, a Rattlesnake in Playa del Rey, in the spring (2005), amidst some California Beechey Ground Squirrel burrow systems and Pocket Gopher soil mounds, near the old horse stable in Playa del Rey.
The Valley Pocket Gopher and California Ground Squirrel are prevalent in the meadowy prairie-like landscape of the Ballona Valley. This piece of land consists mostly of weedy grasses which is the primary food of the gophers and squirrels, which in turn are the prey for the Rattlesnake. By the way, the main staple of food for the pocket gopher throughout the western United States is grasses. Other plants are less important. The same is true for the California Ground Squirrel. Even Lawn turf grasses are suitable to the Pocket Gopher. And by analogy therefore, baseball fields and sports field turf grasses are very nutritious and suitable for the Pocket Gopher as habitat, and consequently it is also suitable for some the predators of gophers, such a the Great Blue Heron and the Great Egret.
The delicate balance of this ecosystem, with its weedy grasses, gophers, squirrels, Burrowing Owls, rattlesnakes, and many other terrestrial organisms is under threat now that planning for wetlands restoration is underway in earnest. It seems likely that the "weedy" and "grassy" habitats will now fall "prey" to the "predator-like" planning process. It is likely that many of the scientists, especially those with a marine biology expertise, are going to recommend that this area be returned to a salt marsh and estuary with pickleplant (Salicornia virginica) as a main goal of the Ballona wetlands restoration. This action of conversion of a meadowy coastal prairie to salt marsh would be disasterous for the Burrowing Owl and prairie raptors such as the Northern Harrier and Shor-eared Owl, and for smaller raptorial-like birds such as the Loggerhead Shrike. This area is also prime habitat for large flocks of Western Meadowlark. This region should remain as "weedy" coastal prairie replete with thousands of gophers. Furthemore, it needs to remain as short-grass prairie rather than tall-grass (bunchgrass) prairie, so that the raptors and ardeids can hunt most effectively. The area is currently suitable for California (Beechy) Ground Squirrel to increase its numbers and join the pocket gopher's large population base, if the Red Fox could be eliminated from this area. Currently, the ground squirrel is nearly extirpated (locally extinct) in the Ballona Valley's wetlands region. A small population of Audubon Cottontail Rabbits have a small refugium in the bushes (pampas grass and Saltbush) along the west-facing levee slope of Lincoln Boulevard because there is a hedge-like habitat vegetation. Along Culver Boulevard there are two giant Arundo stands of 30' high cane-like vegetation which harbors homeless encampments and is cover habitat for Red Fox. A few palms, arundo, and saltbush are beginning to invade the prairie-liek vegetation, which will be bad for the Burrowing Owl, Ground Squirrel, Ferruginous Hawk, and Loggerhead Shrike. If these arundo, saltbush, and young palms were removed, the red fox and human homeless habitat would vanish. The area would then become a prime area for Ground Squirrel again. The Ferruginous Hawk, in addition to preying on pocket gopher and insects, also hunts ground squirrels, and at one time in the past, was named the "California Squirrel Hawk." Let us hope this area remains as prairie. It should be noted that this region, located between Lincoln, Culver, and Jefferson Boulevards, in high precipitation years, is temporarily covered in a shallow sheet of water, at which time it becomes habitat for watefowl such as Mallard, Ruddy Duck, three kinds of Teal, and Pintail. This is only for a few days to a week or two, and then the area reverts back to prairie and the gophers dig themselves out from the soggy landscape that covered the ground above them.
For a second example, consider the Burrowing Owl. Jack Von Bloeker did discuss this bird in his report (see above list), so we have some baseline information on which to make scientific hypotheses, analysis, and conclusions. This owl which cannot burrow itself, depends completely on the burrowing activities of the ground squirrel. Unfortunately, the ground squirrel is locally extinct at Ballona and consequently, so is the owl. So when does an owl actually have a chance to use a squirrel hole for raising its own family of young owls? It depends on a squirrel hole being found vacant due to death of a squirrel. Squirrels die of old-age, disease, and predation by coyotes and hawks, and it is shortly after a death of a squirrel that a Burrowing Owl gains a nesting place. Now you know why the Burrowing Owl is gone from Ballona but why is the Ground Squirrel gone? The Red Fox has been studied throughout southern California and each location where there is a population of Red Fox, there is no ground squirrel, and consequently no Burrowing Owl. Apparently, the Red Fox is a voracious predator of the Ground Squirrel. One small area at Ballona, on private land adjacent to Del Rey Lagoon harbors the last remaining vestige of a population of the ground squirrel, with an estimated population size of about 8 squirrels. Why hasn't the Red Fox discovered this squirrel population. The squirrels are protected by a fence that encloses the squirrel population and the lagoon which historically remained filled with water. However, for the last year, the tides have been allowed to flow in and out of the lagoon, so that now, there are times that the Red Fox can hunt and wander along the shore of the lagoon, right to where the squirrels have been holding on to a small refuge. The squirrel numbers seem less now in this area, and it may already be too late for them. Eventually, the Red Fox eats everything and then it too will disappear.
I would like to conclude this afterword with some obvious observations that Jack von Bloeker discussed but which others think we do not need to manage for at Ballona, namely the Slender Salamander and the Ring-necked Snake. It seems that we on a path of restoration which may eliminate these two small delicate animals. The lower Ballona Valley has become increasingly suitable for this salamander and snake but the state government, via its agency called the Coastal Conservancy, is rushing forwawrd to destroy nearly all the unique fauna and flora of the Ballona Valley in Playa del Rey. Hasn't enough bulldozing that results in diking, filling, and dredging prairire wetlands and vernal pools happened in Playa del Rey. During the time of the fieldwork of Jack von Bloeker, only 60-80 years ago, there were abundant wildlife of the herp-kind. Reptiles and amphibians were everywhere.. How can it be that we have made the Ballona Valley so unbearable for lizards, salamanders, frogs, snakes, and turtles? The efforts at documenting the natural history of Ballona Valley and Playa del Rey's sand dunes by von Bloeker must not be forgotten. That is why I have endeavored to bring his classic study on the herpetology, back into print, via the internet as a Ballona Institute publication. Is it too late to bring back the herps to their former abundance? Not at all. We need simply to reduce the number of trees, reduce the turf-lawns, put-out more boards for lizards and snakes and salamanders to hide under, and stop the bulldozers. If we maintain and also increase wide open prairie-like areas, remove the fox which increase the numbers of the ground squirrels, which in turn increases the hiding places for herps, as they are fond of moving into squirrel holes. Several of the herps are vulnerable to predation by the Red Fox, either directly or indirectly. These herps that are at risk are described by Jack von Bloeker and were found commonly in the Ballona Valley and Playa del Rey region of the City of Los Angeles. The Red Fox has nearly eliminated the squirrels that dig out their burrows. Finally, the Red Fox is a good burrower himself and he digs out the owls and squirrels from their burrows. The Red Fox, single-handedly, more so than the developers, due to its insidious fox-like behavior, has caused a mass genocide on the native wildlife. The Red Fox is an impostor that was brought by Man from Europe via ship and railroad to California, so that fox farms were established to make furs for the growing Hollywood starlets that wanted fox furs to look "beautiful." Thus, indirectly, the loss of the reptiles, amphibians, owls, harriers, jackrabbits, and squirrels is due to the Hollywood phenomenon and human behavior. Are you surprised? Don't be, it is yet one other way that Ecology functions. Ecological systems can collapse and cascade downward into lower biodiversity just as they can build "staircases" of complexity to higher biodiversity. However, building a staircase takes more time and money than tearing one down. Staircases can also need repair and management on a continuing basis. Thus, the metaphor of a staircase for an ecological system is a good one, not unlike Aldo Leopold's metaphor to a wristwatch, more than 50 years ago, in Sand County Almanac.