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Biological Surveys

Biological Overview of Cottonwood Canyon property, Pasadena

February 3, 2013  Mickey Long

Location:  The subject property (ca. 10.44 ac) is located in the Linda Vista Hills, west of the Arroyo Seco and Brookside Golf Course, and south of the 210 Freeway, and trends east to west from east of Linda Vista Ave., across Normandy Drive and westward to Inverness Drive.

Site Visit:  The property was visited on January 28, 2013, in the afternoon, by John Howell and Mickey Long, Arroyos & Foothills Conservancy, guided by Mike and Scott Bishop.

Topography, Soils:  The site is a steep, deep-sided, East-facing canyon with a spring.  Elevations range from ca. 960 ft. at the east end (at Arroyo Seco) to 1360 ft. at Inverness Dr.  Water below a spring flows year-round according to Mike Bishop and the creek has cut its way deep into the slope.  The creek was flowing below the spring at approximately 1 foot wide at the time of visit.  Our access up the slope through the property above Linda Vista was by fairly primitive deer trails along the north side of the creek, and the ground was still damp in most areas from recent rains.  Soils in the lower canyon were of a dark clay, damp and adhering to boot soles.  Soils were loamy under oaks and other trees and shrubs with decomposing leaf litter forming a thick duff.

Plant Communities and Vegetation:  During the brief survey of the lower half of the property and views from the paved roads through the middle and upper portions, 58 species of plants were identified in 33 Families (see Plant list below).  Many more species would be expected if more thorough surveys were conducted in spring and summer.  Plant communities present on the property, in order of dominance or acreage covered were Southern Oak Woodland (Coast Live Oak, Poison Oak),  Coastal Sage Scrub (California Sagebrush, Black Sage, Coast Prickly-pear, Sugar Bush), Chaparral (Chamise, Toyon, Hoary-leaf Ceanothus, California Scrub Oak) and streamside Riparian (Big-leaf Maple, Sycamore).  As with most canyons near the urbanized environment, the property also supports non-native vegetation.  Several species found, primarily in low numbers (Castor Bean, Tree Tobacco) would be invasive and should be targeted for removal to help restore the site.  Typical non-native grasses and mustard are common as understory on the site.

One shrub of note due to distribution is the presence of Fuchsia-flowered Gooseberry (Ribes speciosum) [approx. 10 plants seen - photo], a species uncommon locally (Pasadena area) and not generally found in the adjacent San Gabriel Mtns.

Wildlife:  Mule Deer were seen as we entered the canyon bottom from Linda Vista and tracks and droppings were evident throughout.  Native Big-eared Woodrats (Neotoma macrotis) are very common as evidenced by a high density of large stick nests (photo).  A Red-tailed Hawk (Buteo jamaicensis) was photographed perched at the canyon edge in a tree along Inverness Dr.  Great Horned Owls (Bubo virginianus) use the property as evidenced by at least one large owl pellet collected on site, and dissection indicated the owl had eaten a squirrel.  Few other birds were seen during the visit, probably due to the late afternoon timing, but the habitat should support numerous species typical of the four dominant plant communities.

Wildlife Corridors and Connectivity:  The canyon property habitat connects at the lower end with a linear, north-south trending slope of wild vegetation at the west edge of the golf course and this slope and adjacent Arroyo Seco run north to meet the Hahamongna Watershed Park under the 210 Fwy.   This should serve as a corridor for passage of large and mid-sized wildlife species.  Viewed from aerial photography (Google earth) the upper, west end of the property connects with an expanded open space leading into the higher Linda Vista Hills to the west and south.

Overall Biological Condition and Values:  Much of the property supports a dense oak woodland composed of mature oaks and solid canopy.  Higher, south and east facing slopes support a mosaic of Coastal Sage Scrub and Chaparral stands.  The vegetation overall is in excellent and undisturbed condition.  The presence of a spring and year-round (blueline) stream lends value to the property and supports far more wildlife than the adjacent dryer hills.  Distinct deer trails lead to and from the shaded spring.  While several homes are developed along the north and south rims of the canyon, outside the property, they are generally set back and lower density and are barely seen from deep in the canyon.  In addition, the canyon has some historic significance in that the spring was developed over 120 years ago as part of an early water supply and Cottonwood Canyon Water Company (see Reid, H. 1895.  History of Pasadena).  Pipes from this spring are evident in several places on the lower property, along with early rockwork walls.