NATURAL PERSPECTIVES:

Last week, Vic was the guest speaker at the Orange County chapter of the Society for Conservation Biology. The part of his talk that I found the most interesting was his section on bridges at Bolsa Chica. Only he wasn’t talking about man-made bridges. He was referring to connectedness and the various land, water and air bridges that wildlife use between Bolsa Chica and the rest of the world.

Land bridges may be the most intuitive. Land-based wildlife such as coyotes, raccoons, skunks and opossums use the few corridors remaining to them to travel between Bolsa Chica, Huntington Central Park and the rest of the wild world. Edwards Thumb is one such bridge. It is a narrow strip of undeveloped land that connects the southeastern part of Bolsa Chica to Central Park. Wildlife can move freely over this area with only Edwards Street and a couple of fences to cross.

Even more important bridges are the flood control channels. They aren’t the best habitat, but the weedy growth in the channels provides minimal cover and a safe place for wildlife to move between the isolated pockets of wildland that remain in our heavily urbanized area. The Wintersburg and Slater Flood Control Channels connect Bolsa Chica with Huntington Central Park. The Edinger channel connects the Seal Beach National Wildlife Refuge with the fields of Marina High School, Murdy Park and other areas.

Water is another important bridge. The flood control channels sometimes have water in them, and are part of the water bridge system. But the most important bridges for aquatic life are the new ocean inlet at the south end of Bolsa Chica that connects the new deep water channel to the ocean, and the channel to Huntington Harbour to the north that connects Inner and Outer Bolsa Bays to Anaheim Bay, the Seal Beach National Wildlife Refuge, and ultimately, the ocean. Because many species found in the ocean spend part of their life cycles in coastal salt marshes, the health of Bolsa Chica affects what lives in the ocean. And vice versa.

Finally, there are air bridges. Bolsa Chica is an important stop on the Pacific Flyway. Migratory birds stream through our area on unseen highways in the sky. But they don’t have the benefit of a system of fast food restaurants along their highways. They depend on coastal wetlands such as Bolsa Chica to stock up on protein and energy on their long migratory journeys. For example, more than 450 surfbirds were seen a couple of weeks ago, feeding on invertebrates on the rock jetties of the new ocean inlet. That’s 0.6% of the world population, a rather remarkable number to be in one spot on one day. Normally, we see no surfbirds at Bolsa Chica. Surfbirds breed in Alaska, but winter from southern Alaska south all the way to Tierra del Fuego.

For some species, Bolsa Chica is an end point in their journey. Birds that nest in Canada and Alaska come to Bolsa Chica to spend the winter. Many of the birds that nest at Bolsa Chica in summer arrive here in spring from Central and South America. The air is what connects Bolsa Chica to these far lands.

One of the reasons we sometimes write about far-off events in our columns is things that happen far away can affect our local environment. For example, global climate change has warmed the Arctic by a whopping 10 degrees over the last century. This has affected when insects hatch. This in turn affects the amount of food that is available to bird nestlings. Cold-blooded invertebrates have had their life cycles altered by several weeks by global climate change, but warm-blooded birds have not altered their behavior as much. Birds are migrating a few days earlier, but the much earlier hatch of insects means that there is less food available when bird nestlings hatch.

Prior to global warming, the life cycles of insects and birds were perfectly matched so that nestlings hatched when insects were most abundant. That is no longer the case. Less food means fewer nestlings survive. Thus changing climate in the Arctic affects birds that nest there, but winter down here.

Another example of a bird species that uses air bridges is the Elegant Tern. These birds nest in only five sites in the world. About 90-97% of the population nests at Isla Rasa in the Gulf of California. Most of the rest, about 4,000 pairs, nest at Bolsa Chica, with many fewer birds nesting at three other places in Southern California. The population is at extreme risk from egg harvesting, guano mining and other disturbances in Mexico. Once nesting season is over, all of the terns range along the Pacific Coast from central Mexico down to Chile. Anything that affects the abundance of small fish along the coast from Mexico to southern South America will affect the population of Elegant Terns, and other terns as well. So, far away events can affect things here.

All things in nature are connected. If you tug on the web of life in one small spot, the repercussions can travel all over the world. That’s one of the reasons why we try to keep you informed about things in other parts of the world that may ripple all the way back here. And vice versa.

As Vic said in his talk, “No marsh is an island.”

VIC LEIPZIG and LOU MURRAY are Huntington Beach residents and environmentalists. They can be reached at vicleipzig@aol.com.