Endangered Species in the Santa Clarita Valley
There are three federally listed endangered species in the Santa Clarita Valley. They are:
- Unarmored Three Spine Stickleback (gasterosteus aculeatus williamsoni)
- Least Bell’s Vireo (vireo bellii pusillus)
- Arroyo Southwestern Toad (Bufomicroscaphus californicus)
In addition, the Southwestern Pond Turtle (Clemmys marmorata pallida) is threatened, though not endangered.
Unarmored Threespine Stickleback
(gasterosteus aculeatus williamsoni)
Sticklebacks are small, rather inconspicuous fish with compressed, spindle-shaped bodies, covered with a few bony plates or shields in place of scales. Three sharp erectile spines precede the soft dorsal fin. The mouth is small, with a projecting lower jaw. The ventral fins have sharp erectile spines. Their color is greenish or olive above, grading to silvery on the lower sides and belly. At spawning time, the males have a scarlet throat and belly, blue eyes, and greenish fins. The females at this time have a pinkish throat and belly.
The unarmored threespine stickleback, gasterosteus aculeatus williamsoni, (williamsoni for Lieut. R. S. Williamson, who first collected this subspecies), is usually unarmored, or may have 2 or 3 anterior plates. It is found in several coastal streams in southern California and has been introduced into the Mojave River.
Their food consists of small aquatic organisms, primarily insects and crustaceans. Algae are also eaten. Breeding occurs in the late spring and early summer. The male builds an elaborate nest of grass and sticks stuck together by a glue-like secretion. The nests may be located on the bottom or concealed in holes, cans, bottles, etc. Several females may deposit eggs in one nest. The male guards the nest until the eggs hatch and the young are on their own.
The stickleback provide a particularly interesting case of adaptive variation as each location typically contains a distinctive form of stickleback, quite comparable to the morphological variability in Darwin’s finches.
This species is known to be an efficient osmoregulator and can be found in the lower reaches of rivers and in the salty ditches draining into them. (Osmoregulation is the ability to control the volume and composition of body fluids, especially to adjust the salt balance to cope with different salinities.)
The stickleback may be found in SEA #23, the Santa Clara River.
Least Bell’s Vireo
(vireo bellii pusillus)
The least Bell’s vireo is predominately an insectivore. During the early and mid portion of the nesting season most foraging occurs in the vicinity of the nest site, predominately in willow, Salix spp., Both high and low shrub layers are used as foraging substrate. These birds use non-riparian habitats occasionally and will travel an average of 15m to forage. Birds using non-riparian areas for foraging tend to have territories in the narrowest sections of riparian habitat.
The birds are easily identified by their distinct call, the first part of which sounds like cheedle- cheedle- chee, as if asking a question, and the second part, cheedle- cheedle- chew, as if answering.
A low, dense shrub layer is considered essential for nesting , and a large degree of vertical stratification is preferred. Willow are the most commonly used vegetation for this need. Plant species used for nesting and foraging include the California wild rose, Rosa california, and coastal live oak, Quercus agrifolia. Most nest sites are located near the edges of thickets. Nest height on average is 1m above the ground . Males are site tenacious and return to the same site to nest in succeeding years. Average territory size is about 0.8ha.
Designated endangered by California in October, 1980; May, 1986 by the ferderal government.
The vireo may also be found in SEA #23, the Santa Clara River.
Arroyo Southwestern Toad
The arroyo toad is a small (2 to 3 inches), light greenish gray or tan toad with warty skin and dark spots. Its underside is buff colored and often without spots. A light-colored stripe crosses the head and eyelids, and a light area usually occurs on each sacral hump and in the middle of the back. Its movement consists of hopping rather than walking. Its courtship vocalization is a high trill, usually lasting 8 to 10 seconds.
The arroyo toad is restricted to rivers that have shallow, gravelly pools adjacent to sandy terraces. Breeding occurs on large streams with persistent water from late March until mid-June. Eggs are deposited and larvae develop in shallow pools with minimal current and little or no emergent vegetation and with sand or pea gravel substrate overlain with flocculent silt. After metamorphosis (June or July), the juvenile toads remain on the bordering gravel bars until the pool no longer persists (3 to 8 weeks, depending on site and year) Juveniles and adults forage for insects on sandy stream terraces that have nearly complete closure of cottonwoods (Populusspp.), oaks (Quercus spp.), or willows (Salix spp.), and almost no grass and herbaceous cover at ground level. Adult toads excavate shallow burrows on the terraces where they shelter during the day when the surface is damp or during longer intervals in the dry season.
Arroyo toads were historically found along the length of drainages in southern California from San Luis Obispo County to San Diego County, but now they survive primarily in the headwaters as small isolated populations. Urbanization and dam construction beginning in the early 1900’s in southern California caused most of the extensive habitat degradation. The species was formerly distributed southward along the northwestern coastal region of Baja California, Mexico, to the vicinity of San Quintin.
Most remaining populations in the United States occur on privately owned lands, primarily within or adjacent to the Cleveland National Forest. Less than 50 percent of the known extant populations of arroyo toad occur in areas owned or managed by the Forest Service (Los Padres, San Bernardino, and Cleveland National Forests). Due mostly to habitat destruction, only eight drainages remain where populations of this species may be viable. In 1990, only seven pairs of arroyo toads were known to have bred anywhere within the toad’s range. Due to the isolation and the small sizes, almost all populations are at great risk of extinction.
Southwestern Pond Turtle
(Clemmys marmorata pallida)
The southwestern pond turtle inhabits slow moving permanent or intermittent streams, small ponds, small lakes, reservoirs, abandoned gravel pits, permanent and ephemeral shallow wetlands, stock ponds, and sewage treatment lagoons. Pools are the preferred habitat within streams. Abundant logs, rocks, submerged vegetation, mud, undercut banks, and ledges are necessary habitat components for cover as well as a water depth greater than 2 meters. Additionally, emergent basking sites, emergent vegetation and the availability of suitable terrestrial shelter and nesting sites seem to characterize optimal habitat. Adjacent upland areas typically provide overwintering and estivation sites.
The turtle’s daily activity revolves around thermoregulation and foraging patterns. It often suns itself at the edge of water, or on branches or stones above water. It is secretive and will seek refuge at the bottom of a pond or stream at the slightest disturbance. In the early morning and evening, pond turtles may move up or down stream, moving from one pool to the next in search of basking sites, mates or foraging. Northern populations tend to forage early in the morning, then usually begin basking between 0900-1000, and continue basking intermittently throughout the day. They usually terminate basking at around 90-95 degrees Fahrenheit (F.), maintaining a body temperature of 75-90 degrees F. for most activities. Foraging may occur during the late afternoon or early evening during the warmth of summer. Often they will remain quietly on the bottom of pools to avoid a critical thermal maximum of 104 degrees F.
Loss and alteration of aquatic habitat is the greatest threat to the western pond turtle. Over 90% of wetland habitat within its historic California range has been eliminated by agricultural development, flood control, water diversion projects, and urbanization.