Western pond turtles have been subjected to many indignities over the years, but the latest threat to the sad-eyed reptiles comes from a surprising source — rampaging do-gooders.

Wildlife biologists say would-be good Samaritans have been snatching native turtles around California this spring in ill-conceived attempts to save them from doing the kinds of things turtles do.

Wildlife rehabilitation centers and animal shelters have complained that people have been bringing healthy Western pond turtles to their sites. The good-hearted but ill-informed folk have wrongly perceived distress as the turtles have waddled out of water, ambled up hillsides, moseyed about through grasslands or simply looked off into space with what appeared to be a needy gaze, said Laura Patterson, a senior environmental scientist for the California Department of Fish and Wildlife.

“They think they are either lost pets or they are confused, I guess, or in a place that they shouldn’t be, so they are taking them often to dog and cat animal shelters, where a lot of times workers don’t even know what they have,” said Patterson, the department’s statewide amphibian and reptile conservation coordinator. “I’m sure it happens a lot. Statewide it is probably in the hundreds.”

Pond turtles are certainly partial to water, she said, but the olive brown creatures have been known to gallivant about on land, too. Spring is nesting season, and many pregnant females are venturing out from their aquatic habitats in search of cozy substratum to lay eggs. Pond turtles sometimes wander as far as 500 yards away from water to deposit their offspring, which they promptly leave to their own devices. They have been spotted prowling the highlands as far as a mile away from their native streams.

Moving upland earlier

Experts say scarce water caused by the worst drought in recent California history has also caused more turtles to move upland earlier in the season to “estivate,” or go into summer dormancy. Patterson said the reptiles have evolved in a way that allows them to go into a kind of suspended animation for long periods when there is no food or water. The turtles sometimes bury themselves during hard times to wait things out.

The Western pond turtle, which generally reaches a maximum length of 7½ inches, is California’s only native freshwater species of turtle. They were once abundant in Bay Area wetlands, creeks and sloughs, and much of their Bay Area habitat has been filled in, destroyed or overrun by invasive species over the decades.

The pond turtle population has gone down everywhere, but the decline has been particularly precipitous in Southern California because of habitat loss, predation, competition and diseases from nonnative species.

The species’ primary turtle nemesis is the larger, more colorful red-eared slider, an alien species from the East that is commonly sold in pet stores. Unfortunately, sliders are often dumped in local ponds and outcompete the drab-looking brownish pond turtles for food.

Sliders, which have yellow-and-green striped shells and telltale red markings on their heads, have contributed to huge declines in pond turtle populations, including some localized extinctions, according to biologists.

Western pond turtles are listed as a “species of special concern” in California, “critical” in Oregon and “endangered” in Washington. The U.S. Fish and Wildlife Service announced in April that the species may warrant protection under the federal Endangered Species Act.

Strict conditions of release

It is illegal to capture, collect, possess, purchase, propagate, sell or transport native reptiles or amphibians in California. The recent terrapin expropriations are also a problem because animal shelters and wildlife rescue centers are not allowed to release captive turtles without a clear understanding of how and where they were captured.

“They can only release them under strict conditions near where they were taken from the wild,” Patterson said. “We are very careful ... because of concerns about disease transmission and genetic mixing. So when people just drop them off and we don’t know where they came from, we may not want to risk releasing them back into the wild. To me, that’s the tragedy of this.”

The Department of Fish and Wildlife is urging tenderhearted nature lovers to stay away from the slow-moving reptiles unless the animal’s shell is cracked or it is obviously injured. Patterson said it is probably OK to move a turtle off a roadway or out of harm’s way, but nobody should ever take one home.

“It’s well-meaning but very counterproductive behavior,” she said. “We just want people to know that the best thing to do is leave them alone.”

Peter Fimrite is a San Francisco Chronicle staff writer. E-mail: pfimrite@sfchronicle.com Twitter: @pfimrite

Western pond turtle

Scientific name: Clemmys marmorata

Status: Species of concern in California

Length: Up to 7½ inches

Weight: Varies

Sexual maturity: 6-7 years

Mating season: Mid- to late spring

Number of young: 1-13 leathery, oval white eggs

Lifespan: 40 to 70 years

Diet: Aquatic plants, insects, small fish and decaying material

For a brochure on the reptiles, visit http://tinyurl.com/ljy5cmu.