San Diego Zoo’s two resident giant pandas Bai Yun and Xiao Liwu were returned to China, leaving the zoo panda-less for the first time in 20 years as a result of President Donald Trump’s trade war.
Giant pandas have become a symbol of endangered species, but through conservation efforts their population has increased to 1,800. It is possible to bring back endangered species from the brink, it just requires people to care enough to try.
In the San Diego region there are plenty of endangered species that do not get enough love as the World Wildlife Fund (WWF) mascot, but protecting them is of great ecological importance.
Many of the endangered or threatened species found locally were put in that position by Americans encroaching on their natural environment, like Chinese did to the giant panda.
Humans working together, however, are capable of turning the tide of extinction.
Last month seven light-footed Ridgway’s rail took flight as they were released by conservationists into the Tijuana River estuary. Were it not for the efforts of Dr. Mike and Patricia McCoy in the 1970s to prevent the estuary from being dredged into a marina, there would be no place to release these birds. They would have become extinct in Southern California.
Ridgway’s rail is a small chicken-sized bird that feeds primarily on mollusks, worms and crabs found along the mudflats. They have been slammed by reckless development in the U.S. and filthy runoff from Mexico.
In March 2016 a large scale El Niño caused the mouth of the Tijuana river to become blocked and resulted in a buildup of tainted runoff ruinous to the ecology of the Tijuana estuary. Among the victims were at least 50 leopard sharks trapped on the wrong side of the river’s mouth.
U.S. Fish and Wildlife Service officials estimate the number of rails grew from 142 pairs in 1985 to 656 pairs in 2016. Rail populations declined sharply during the blockage of the inlet, when lack of tidal flushing poisoned the invertebrates that are the rail’s primary food source.
A rail recovery study warns that “saltmarsh habitat(s) [are] threatened by a combination of development, erosion, contaminant leaching, alteration of hydrology and sediment transport, and sea level rise.” In areas that become completely flooded by high tide, the rails are forced out of the safety of their tall cordgrass environment and have to brave urban areas and are more likely to face predation.
Biodiversity is an essential aspect of conserving endangered species. When a population becomes too small, its genetic diversity collapses, leaving it susceptible to the damaging effects of inbreeding.
A species needs to have a wide range to ensure genetic diversity so that if an incident like the 2016 El Niño event occurs, there are enough individuals left to repopulate.
San Diego County is the most biodiverse county in the continental United States, according to conservation organizations like The Nature Conservancy and Conservation International, which called San Diego County one of 36 “biodiversity hot-spots” on the planet.
These hot-spots are defined as having “at least 1,500 vascular plants as endemics” and “30 percent or less of its original natural vegetation.” That means San Diego county is full of plants that are found nowhere else on Earth, but threatened by invasive species.
Conservation International scientists wrote “[biodiversity hot-spots] represent just 2.4 percent of Earth’s land surface, but they support more than half of the world’s plant species as endemics — i.e., species found no place else — and nearly 43 percent of bird, mammal, reptile and amphibian species as endemics.”
Almost every natural environment in San Diego has been impacted by human development. Mountain bikers on Madre de Miguel Mountain that touches Chula Vista have created a huge erosion “scar” on the mountain visible three miles away from Southwestern College. People traversing the mountain unwittingly damaged and killed endangered plant species such as the San Diego barrel cactus. Poorly maintained trails led to the creation of several unauthorized trails that damaged endangered wildlife that live on Mt. Miguel, Madre de Miguel and Hill 985.
In August the San Diego National Wildlife Refuge partnered with San Diego Association of Governments and the San Diego Mountain Biking Association, with assistance from the Bonita Bikers, to repair the badly eroding Mother Miguel Trail.
National Wildlife Refuge ecologists wrote “this trail reroute will reduce the negative impacts to species like Mexican flannelbush, San Diego barrel cactus, Quino checkerspot butterfly and California gnatcatcher, and their habitats.”
It will take some time for the scar to heal, but at least there is now an effort to save these three Sweetwater Valley-region peaks.
These species and others are also threatened by the construction of the proposed southern border wall. If completed, the wall would harm people seeking refuge in the U.S. and damage the ecosystem the wall would vivisect.
Vernal pools are also threatened by human activity. These little-understood ecosystems comprised of seasonal ponds have suffered extreme degradation as humans build over them. They are seasonal bodies of water 2-12 inches deep that host unique animals like the fairy shrimp, whose eggs are able to survive being dried out until the next rain replenishes their pools.
Fairy shrimp are an important food source to salamanders, water birds and aquatic insects, but most vernal pools have been lost to human development. Between 1979 and 1986, 698 acres of already-rare vernal pools were eliminated. Now only 65 acres of this environment is left and existing pools are threatened by pollution.
A City of San Diego Vernal Pool Habitat Conservation Plan (VPHCP) from October 2017 concluded that fairy shrimp found in 137 vernal pool complexes distributed across the region, but 28 have been completely or partially lost to urban development.
VPHCP seeks compromise between the competing interests of development and conservation by forcing developers to set aside certain areas for the preservation of vernal pools.
Just as no man is an island, lifeforms in ecosystems cut off into islands are generally doomed.
Environmental fragmentation isolate populations from each other and force them to brave the dangers of human settlement.
The California mountain lion struggles to repopulate because they keep getting hit by vehicles or poisoned by eating prey contaminated with rodenticide. Santa Cruz Puma Project tracks about 40 mountain lions in the Santa Cruz mountains and has found that they generally avoid freeways, but are forced to risk death to find prey or mates.
California is home to about 5,000 remaining mountain lions, but they are vulnerable.
One form of environmental protection that would benefit this species and others would be the creation of wildlife bridges and tunnels that safely connect natural areas. The largest of these projects is an $87 million overpass covered in greenery that would span 10 lanes of Highway 101 northwest of Los Angeles.
These green bridges and tunnels, like the Vernal Pool projects, are a step in the right direction but are not a cure for the problem. Human development has had little regard for the natural environment.
We must prioritize Mother Nature before it is too late.
