Revision as of 11:00, 6 April 2020

Summary

The California Tiger Salamander (CTS) of the Central Coast Region is a genetically distinct subgroup of the Central California Distinct Population Segment (DPS), one of three DPS in California. In 2004, the Central Coast DPS was federally listed as threatened under the Endangered Species Act and in 2010 received the same listing from the State of California under the California Endangered Species Act. In 2017 the U.S. Fish and Wildlife Service released a recovery plan specific for this DPS.

Classification

Kingdom Animalia

Phylum Chordata

Class Amphibia

Order Urodela

Family Ambystomatidae

Genus Ambystoma

Species californiense

Description

CTS is a large and stocky terrestrial salamander with a broad, rounded snout. Adults range in length from approximately 6 to 9.5 inches and have a black body with white or yellow markings. This color pattern may serve as a warning to potential predators, as adults produce noxious skin secretions from the dorsal surface of the tail. CTS larval coloration can vary, but larvae are generally pale colored. Larvae are fully aquatic with external gills and a fin along the length of their back. Upon metamorphosis, the gills and fin disappear and lungs and four legs are fully developed.

Habitat

Central Coast Region CTS primarily inhabit coastal grasslands and open woodlands that contain vernal pools and ponds. Vernal polls likely provide higher quality breeding habitat because they are less likely to contain predators that feed on salamander larvae such as aquatic insects, fish, bullfrogs, and non-native salamanders. However, CTS have begun to more frequently occupy livestock ponds and perennial ponds, perhaps due to habitat fragmentation. This species is not known to breed in streams or rivers.

Large tracts of upland habitat are necessary for the survival of CTS. They require areas that are occupied by small mammals such as the California ground squirrel and Botta's pocket gopher because they build underground tunnel systems that are used by the CTS through the year. Large, continuous areas of scattered breeding pools that also contain terrestrial habitat that contains these burrows are ideal to ensure that recolonization can occur if a population at an individual pool is wiped out.

Life History

Breeding

Adult CTS engage in mass migration events during a few rainy nights per year, typically from November through April. During these events, adults leave their underground burrows and return to breeding pools to mate. Trenham et al. found that in Monterey County, males remained in breeding ponds for an average of 44.7 days while females remained for an average of 11.8 days before returning to their underground burrows. Females lay their eggs in the water, attaching their eggs to twigs, grass stems, or other debris. Incubation time is likely related to water temperatures and eggs have been found to hatch anywhere between 10 and 28 days. Peak emergence dates for metamorphs in Monterey County range between May 27 and July 29. Once a metamorph leaves its natal pond and enters a burrow, it spends the majority of its life underground. Little is known about their underground behavior, as they are difficult to observe.

Diet

CTS larvae feed on aquatic invertebrates such as zooplankton, small crustaceans, and aquatic insects. Larger larvae have been known to consume the tadpoles of Pacific chorus frogs, western spadefoot toads, and California red-legged frogs. The diet of terrestrial sub-adult and adult CTS includes spiders, earthworms, and insects.

Predators

Observed predators include:

• Great blue heron
• Great egret
• Western pond turtle
• Various garter snake species
• Western spadefoot toads
• Raccoons
• Striped skunks
• Ravens
• American acocet
• Foster's tern
• Various gull species
• Giant water bugs
• Predaceous diving beetles
• Waterscorpions
• Dragonfly nymphs
• California red-legged frog
• American bullfrog
• Ground squirrel
• Western mosquitofish
• Barred tiger salamander
• Hybrid tiger slamander

Threats

General threats

The loss, degradation, and fragmentation of CTS habitat as a result of human activity are the primary threats to the population in the Central Coast Region. Agricultural conversion, urbanization, road construction, and other development projects have degraded critical aquatic and upland habitat. Other major threats include:

• Habitat loss
• Habitat fragmentation
• Habitat alteration
• Disease
• Predation
• Mortality from road crossings
• Hybridization with non-native barred tiger salamanders
• Pond duration and availability
• Contaminants
• Livestock grazing
• Climate change

Major issues in Monterey County

Hybridization

Hybridization with non-native species can have negative effects on CTS populations. This is particularly problematic in the Salinas Valley, where there was a large-scale introduction of non-native barred tiger salamanders to support the region's bass-bait industry approximately 60 years ago. Today, hybrid populations dominate Monterey County. In 2002, four populations of hybrids were found by Shaffer and Trenham, and in 2004 the California Fish and Wildlife Service found that 78% of the Central Coast Region population was threatened by hybridization due to close proximity (within 1.3 miles) to known non-native and hybridized tiger salamander populations.

In addition to contributing to a genetic loss of pure CTS alleles, hybrids compete with native CTS for habitat and resources. Unlike native CTS, non-native and hybrids prefer permanent ponds which tend to be larger and have more consistent breeding and recruitment opportunities over time, contributing to a much higher reproductive success rate.

Fort Ord

Conservation

Links

• Special Status Animals in the Central Coast Region
• Conversion of Carr Lake to a Multi-Use Park

References

Disclaimer

This page may contain student work completed as part of assigned coursework. It may not be accurate. It does not necessary reflect the opinion or policy of CSUMB, its staff, or students.