Invasion at the Andree Clark Bird Refuge!!
by Ria Boner, Santa Barbara Zoo
They come in various colors, but typically shades of green. Some can regenerate from their own fragments! Some are capable of producing toxic chemical compounds! Some can grow 9-30ft tall! But ALL of them are invading and wreaking havoc on the locals – right in our own city! But no, we’re not talking about extraterrestrial aliens – these are invasive plant species at the Andree Clark Bird Refuge.
Certain plants thrive when moved out of their native habitat and away from their usual predators. Without any natural processes to keep these species at bay they grow out of control, overwhelming local vegetation and the wildlife that feed on it. Invasive plant species can dramatically alter an ecosystem, changing things such as hydrology, soil chemistry, and overtaking the species diversity of an area. For example, cape ivy (Delairea odorata) grows in such abundance that it can block the sunlight to other vegetation and seedlings, vastly reducing species diversity and replacing it with a plant that, due to its toxic nature, is unsuitable for most animals to eat. It can grow so densely that its weight can cause some trees to fall! While these invaders might not take over the entire planet like a UFO Sci-Fi movie, they can take over important habitats and ecosystems.
One of these ecosystems being invaded is the Andree Clark Bird Refuge. Established as a bird refuge back in the 1920s, this natural area provides habitat for 228 bird species, including 43 species that breed at the site and five federally listed endangered species. Certain birds rely on the cottony seeds of the native willow (Salix exigua) to build their nests, others on the sweet nectar of the local hummingbird sage (Salvia spathecea), and many benefit from the nutritious rose hips of the California rose (Rosa californica). But if you were to take a Santa Barbara Zoo train ride along the refuge’s edge back before 2010, you would find it quite a challenge to spot these plants or the wildlife that rely on them. Over 100 Myoporum lateum trees, large stands of giant reed (Arundo donax), the sprawling cape ivy, and other various invasive species had taken their place. The thriving fauna once found in this area was struggling to keep up.
|Left: invasive Myoporum trees and cape ivy before removal at the Santa Barbara Zoo. Right: the same view after removal.|
But as in any classic alien invasion story, there is a hero. Together Channel Islands Restoration, The City of Santa Barbara, and the Santa Barbara Zoo have helped restore the refuge area for half an acre along the train tracks. After the removal of the larger trees and giant reed stands, groups of volunteers armed with gloves and hand tools were enlisted to help keep the invaders at bay. Furthermore, the volunteers helped plant 635 native species that were specially propagated from seeds and cuttings of the remaining natives found at the site. By continually managing the site, our team is able to pull any freshly sprouted invasive species and cultivate the native plants to give them a better chance at resistance in the future.
|Left: invasive Myoporum trees. Right: the same view after removal by Channel Islands Restoration.|
The battle was hard fought, with over 340 volunteers and staff joining the cause in the past two years. But it was well worth the effort. Last week during another volunteer event, a California towhee was seen fluttering about, foraging among the plants. A red-winged blackbird was seen perched on a willow branch. While there is still work to be done and invasive species to combat, the restoration effort over the past two years is making a difference for the wildlife found on the refuge.
|Volunteers learn about invasive plants from Channel Islands Restoration staff at the Santa Barbara Zoo|