It comes as no surprise that natural areas are rapidly disappearing. Urban and suburban sprawl continue to fragment open space into “islands,” or little disconnected pieces of intact habitat surrounded by human development. Undoubtedly, this fragmentation has negative effects on wildlife. Several organizations and universities worldwide are studying the phenomenon of wildlife living in urban, suburban, and otherwise insular areas, with hopes of obtaining information to make wise and positive decisions for the future.
The Santa Monica Mountains National Recreation Area has been conducting a carnivore study since 1996, with a goal of understanding how carnivores are living in an urbanized and fragmented landscape, and how they are affected by these forces. Species of focus include mountain lions, bobcats, and coyotes. Large carnivores inherently require vast home ranges, or tracts of habitats in which the animal lives and travels, in order to acquire resources and avoid interference with competing individuals. This is more pronounced with solitary animals, including mountain lions and bobcats, who only live in the company of others during cubhood and mating. In an area of limited connected natural habitat, the question arises, how are these animals with large home ranges making use of the land? Do their home ranges encompass urban areas or require them to cross highways? Are their populations affected by this limited amount of intact habitat?
Highways are significant obstacles to wildlife movement. Despite the high risk of mortality, animals are crossing these daunting barriers. The Santa Monica Mountains carnivore study has tracked radio-collared animals and confirmed their movement across highways. In the San Francisco Bay and Monterey Bay areas, Connectivity for Wildlife is studying wildlife movement across anthropogenic barriers and determining key wildlife corridors. By employing the use of motion-activated infrared cameras, they have determined that many animals have been using culverts under highways and roads.
Although the animals are crossing these major obstacles, their movement between habitats on either sides of the roads is significantly impeded. The Santa Monica Mountains carnivore study has found that bobcat and coyote home ranges are mostly on one side of the 101 freeway or the other, and that there was twice as much genetic variation in bobcats between sites across the 101 than between sites on the same side of the freeway. Additionally, they have found significantly reduced genetic diversity in mountain lions south of the 101, which is one of the most insularized areas of mountain lion habitat. A study conducted by Dickson et al. in 2005 found highways to be major player in reducing gene flow between local populations in the Santa Ana Mountains.
In areas of isolated or insular habitat, many species may experience the founder effect, where a small population is segregated from the larger population and inbreeding results. A lack of genetic diversity can have negative effects on the fitness of individuals and the viability of the local population as whole. In order to preserve genetic exchange between different local populations, it is critical to determine and preserve key corridor areas, or areas linking intact tracts of habitats.
Multiple highways worldwide have recently been equipped with wildlife crossing structures. In many instances, animals have been using crossings not intended for wildlife, such as culverts, or underpasses. In other areas, park systems and governments have decided to install underpasses or overpasses specifically for wildlife. In Banff National Park, Canada, twenty-two underpasses and two overpasses were designed to increase habitat connectivity across the Trans Canada Highway, with a high degree of success. In Florida, twenty-four wildlife underpasses and twelve modified bridges have been implemented along a 40-mile stretch of Interstate 75, designed specifically to protect the endangered Florida Panther. The Netherlands has installed over 600 wildlife crossings to protect the endangered European Badger as well as red deer, roe deer, and wild boar.
The Santa Monica Mountains carnivore study advocates the construction of a culvert or tunnel at Liberty Canyon to conjoin the open space behind Chesebro Road with that on the South side of the 101 abutting the Santa Monica Mountains. This would provide connectivity between carnivore populations in the Santa Monica Mountains with those in the Simi Hills and Ahmanson Ranch areas. The fate of the open space behind Chesebro was up in the air until October 29th, when the Santa Monica Mountains Conservancy and Advisory Committee voted in favor of applying for grants to purchase the land from the City of Agoura Hills, and preserve it as open space.
For more information on carnviores in the Santa Monica Mountains and Greater Los Angeles area, visit Urban Carnivores
Since 2010, Havasi Wilderness Foundation has been helping to fund the Resource Conservation District of the Santa Monica Mountains’ outdoor education programs. Programs take place at Topanga State Park and Malibu Lagoon, each with their own unique focus. On Wednesday, October 17th, we visited a program at Topanga State Park, where children learn about the ecology and natural history of the Chaparral environment, and how the Native American tribes of the area lived off the land. Castlebay Lane Elementary’s 4th graders were participating in the field trip on this bright and sunny fall day.
Students arrived at the entrance to Topanga State Park, situated among oak tree groves and dry meadows. Before breaking off into groups, the kids formed a big circle and sang along to a few Native American greeting songs, led by one of the educators. The educator told the kids that this site was where the Tongva and Chumash tribes used to meet and trade, and that they exchanged greeting songs upon meeting.
Students then broke off into groups, each with their own educator to guide them. Groups rotated through several different activities. The first group we followed took a hike through the Chaparral, where they spotted Acorn Woodpeckers and learned to identify different native plant species. The educator showed the students how Acorn Woodpeckers use dead tree trunks as “pantries” to store their acorns, and told a Native American story about how the woodpeckers got their laughing sound. She pointed out an Elderberry shrub and told the students how the Chumash used the branches to construct the framework of their homes.
Another group of students were following their guide through an oak thicket. While passing the oak trees, the educator identified poison oak. “Leaves of three, let it be!” she told the students, helping them to recognize and avoid the precarious plant, which can cause severe skin irritation if touched. She then pointed out a large clump of branches tangled together next to the path. She told the students that it was a wood rat’s nest, and pointed out that it had some poison oak branches surrounding it.
“Why would a wood rat put poison oak on its home?” she asked.
Instantly, one of the students chimed in, “So that no one will want to go inside.”
“Very good,” she replied. “For protection!”
Probably the most popular activity of the day was the acorn grinding station. Students sat down on a blanket in the shade of an old oak tree while their educator taught them about a staple of the Chumash diet: acorn meal. Children paired up and were given acorns to grind with a mortar and pestle as the Chumash once did. The educator then explained that the acorn meal must be rinsed with water to remove the tannic acid before eating.
Another group of students were sitting at a picnic table in the shade. The educator passed around two sets of items: one natural and one man-made. The natural set included an abalone shell, a horsetail reed, a soap lily bulb, and a yucca fiber. The educator showed each man-made product, and then matched it up to its natural equivalent which the Native Americans used before these products were invented. She told the students that the abalone shell was used as a bowl, the yucca fiber as twine or string, the horsetail reed as a nail file, and that the soap lily bulb would produce a lather when mixed with water.
It was very apparent how much the students enjoyed their opportunity to learn outside of school, in the best classroom of all: nature!
For a complete set of photos, visit our facebook page: www.facebook.com/havasiwf
All photos by Sandor Havasi
The second largest of the California Channel Islands, Santa Rosa Island is a unique and invaluable site with a wealth of important natural resources and historical remains. The Arlington Springs Man, potentially the oldest remains of a human skeleton in the United States, was discovered on this island and is presumably twenty-six times older than American written history. Remains of the Pygmy Mammoth, a Pleistocene species unique to the Channel Islands, have been discovered on Santa Rosa Island as well. Presently, Santa Rosa Island is home to several species that are only found in the Channel Islands, including the critically endangered Island Fox.
This August the Havasi Wilderness Foundation gave a grant to California State University Channel Islands to support the initiation of a research and education project on Santa Rosa Island. CSUCI has begun a partnership with the National Park Service to collaborate on this project, however, additional funds were sought to provide logistical support and cover start-up costs for the project. Havasi Wilderness Foundation is enthusiastic about this project as it aligns with the foundation’s mission. Funds will help establish a research station on the island and implement hands-on educational programs in the fields of ecology, archaeology, and paleontology. Graduate and undergraduate students will gain fieldwork experience in this unique ecosystem and learn from professionals visiting the research station. Additionally, the project will provide information for making sound management decisions in the future regarding the ecology and natural resources of the island.
Whether naturally ignited or caused by man, fires are an inevitable part of life in Southern California. California’s history is dotted with wildfires, many severe and engulfing large tracts of the landscape. The 2009 Santa Barbara Fire, October 2007 wildfires, Cedar Fire of 2003, and 1993 Malibu Fire, among others, are recent memories of particularly devastating events. Undoubtedly, more wildfires will occur in the future.
As with Earthquakes, the question is not if the next wildfire will occur, but when. Records indicate that infrequent wildfires are a natural part of the ecology of the region we live in, although the interval between fires has shortened in recent times. In the Chaparral biome, the scrubland community that encompasses much of the Coast Ranges and foothills of several interior mountain ranges, the average fire interval is thirty to forty years. In certain areas the typical interval between fires can drop as low as ten to fifteen years, and span up to one hundred years in others. It has been estimated that the fire regime was much less frequent before human settlement: between thirty and one hundred fifty years. It has only been within the past century that the interval has shortened dramatically.