Natural History

Robin Irruption!

 

American Robin

Licensed under CC: Photo by Flickr user Lucina M. All rights revert to originator.

Thousands of robins are visiting California’s central coast: lots more than usual, an ‘irruption.’ Unfortunately, I lack records of the timing of their arrival, but many people are talking about their astounding numbers, including: Feynner at Big Creek Reserv
e in Big Sur and Brock Dolman in Occidental, Sonoma County…and birders with the Monterey Bay Birds list serve. Feynner’s says maybe they came this way to avoid big burned areas inland and North. I counted 200 in about 10 minutes, flying in squeaky-talkative groups across a North Coast Santa Cruz field. This has been a daily occurrence for many weeks.

I have spent a little while standing among flocks of hundreds of robins in the fields and orchards at Molino Creek Farm, watching them. They scratch the mulch under the apple trees or poke at the ground in the fields, each bird holding their own few square feet. Some birds rest, alert high in nearby branches in two’s and three’s. I hear the crackle crackle crackle-squeak of a perturbed bird chasing away another, too close; they chatter their beaks by clicking them together rapidly when they seem especially territorial in a favorite food spot. These birds are apt to live up to the cliché, a worm hanging sideways out of their mouths.

Robins were Rachel Carson’s indicator species for the ‘Silent Spring.’ In 1950’s Michigan, researchers documented that elm leaves containing a pesticide applied to battle Dutch elm disease were digested by earthworms, and the earthworms by Robins. Pesticide poisoning made the Robins’ egg shells too thin, and they faced reproductive failure at a landscape level.  Mornings got quieter and quieter in the Great Lakes states as the friendly dawn chorus of Robins quickly faded. Thanks to Rachel Carson and a host of others, America woke up and stopped large-scale broadcast spraying of pesticides.

Robins seem especially wise. Their gaze is intent. Someone once saw an American Robin sweep leaves aside using a twig- tool using intelligence. I imagine their vocal chatter is carrying lots of information. Their friendliness towards me suggests that they know I don’t eat them- people once hunted them for food. They are still food, but for other species: while hiking the other day, I walked towards a cacophony of Robin voices. As I do for all flocks, I spoke gently saying “don’t worry about me!” But, they wouldn’t stop and, after another dozen strides at my feet was a freshly dead Robin, neck broken, just killed…probably by a Cooper Hawk. Cooper Hawk and Sharp Shinned Hawks must be well fed this winter.

I’m pleased to have witnessed this Robin irruption, reminding me that terrestrial ecosystems of the Western United States can still produce bird abundance. This is the third irruption in recent years. 2014 was the Varied Thrush irruption. Winter of 2012/2013 was a Red Breasted Nuthatch irruption. What next? Don’t miss this one! Take time at dawn or dusk in the fields around the Central Coast to see the many Robins and hear their “chock chock” talk. (Check out their big beaks, too!).

Santa Cruz County’s North Coast is Amazing, Naturally

Shark_Tooth_Rock_&_Davenport_Beach

Licensed under CC: photo by flickr user Elaine with Grey Cats. All rights revert to originator.

Santa Cruz County’s North Coast is an outstanding natural area because of climate, geology, unique species, rare habitats, and unusual natural processes. The North Coast combines two climatic features that shape its biological splendor: proximity to the cool Pacific Ocean and an adjoining Mediterranean climate. This climate drapes across the Franciscan Formation, a mélange of geological formations creating diverse soils and topography. Climate and geology alone could explain the many interesting and unique species, but North Coast richness is also due to the Santa Cruz Mountains having been evolutionarily isolated by ocean, bay, or extensive freshwater wetlands/river systems. All of the aforementioned combine to shape many rare habitats, in close proximity. In turn, Santa Cruz’ North Coast produces ecological phenomenon, processes, that we are only just beginning to appreciate.

The North Coast’s climate is found in few places of the world and is unique in North America. The roasting of interior California pulls cool, foggy air across the coast. Fog helps plants and animals make it through the dry summers. The wet winters combined with the very dry summers make it possible for moisture or arid loving species to coexist. With the right prevailing winds, mountains close to the ocean make rain. At 2660 feet, Ben Lomond Mountain is the backbone of the North Coast, assuring that the North Coast gets first dibs on rain from the winter storms which normally blow down the coast. During long droughts, fog and Ben Lomond Mountain’s claim on winter rains have maintained species that would have otherwise gone extinct. And so, we have extraordinary species diversity along our foggier and rainier coast in comparison to inland.

Besides weather, Ben Lomond Mountain is also responsible for our geology. The ‘basement’ of the Mountain consisting of granitics, schists, and crystallized limestone, pushed up through younger sandstone, mudstone, and shale. The diverse rocks create diversity you can easily experience:  granitic stream boulders…craggy schist and sandstone cliffs…inland sand dunes…soil-less mudstone ridges contrasting with wide, deep soiled mudstone terraces…extensive subterranean limestone caverns.

For all of the above reasons, the North Coast affords many different species good places to live. More than 50 rare, imperiled, threatened or endangered species depend on this relatively small area (see prior blog, this website). This is why Santa Cruz County is known as a biodiversity hotspot: this small county has many species of Federally or State-recognized rare ‘herptiles,’ insects, and plants. A host of species are only found locally. For instance, the North Coast has two Manzanita species only on the North Coast. And, the caves of the North Coast are home to a host of species found only in North Coast caves. Even more widely distributed rare species, such as the California red-legged frog, probably depend on the North Coast for long-term survival on Planet Earth. My list of fifty sensitive species from the North Coast will grow because: 1) I haven’t added bats and mushrooms, yet, and; 2) Randy Morgan’s insect collection at the UCSC Natural History museum includes numerous new species, especially of bees, that have yet to be described and may exist only locally. So, more to come…

The habitats of the North Coast are wonderfully diverse. Redwood forests, dunes, grasslands, chaparral, oak forests, wetlands, beaches, cliff faces, streamside forests, lagoons…so many habitats, so close together! Many of these habitats are rare, and all experience a mix of fire, grazing, soil disturbance, and wind storms that shape them. Coast redwood forests are only in a narrow band on California’s coast, dripping fog moisture that supports lush understory plants through the summer. Dunes at the bigger beaches blossom year round with native plants, roots deep in the sand. Forty-five or more types of coastal prairie blanket flat uplifted marine terraces, cap rocky outcrops, or hold up vertical wildflower-covered slopes. Chaparral here, a.k.a. “maritime chaparral,” is like no other scrubby habitat, with many shrub species in poor soils, fed by networks of diverse fungi. Hundreds of species of fungi can be found under a single shrub in maritime chaparral. Stands of coast live oaks on the edges of grasslands are quintessential North Coast scenery. Less recognized are the dark green Shreve oak forests, acorn-strewn tan oak stands, patches of stately canyon live oaks, or shrubby interior live oak covered ridges. A very few natural, but many man-made, ponds are a-bob with amphibians; more common are the ephemeral wetlands on the terraces, or on top of rocky ridges…replete with odd algae, mosses and liverworts. Beach habitats, though nearly obliterated by human feet, still hang on along the less trammeled fringes. Above the beaches, and framing steep canyons, are the many nearly uncharted cliff habitats – so many mysteries. And, then there are the willow and alder forested canyon bottoms. Downstream, lagoons pulse fresh to salty with the changing tides and wave action: nurseries for salmonids, home to silvery goby fish and ducks. This diverse habitat-scape contrasts strongly with the grassy rolling plains of the Midwest or even the forests of the East Coast, where one habitat stretches for miles in every direction.

The biologically-produced ecological processes that this landscape supports are my real fascination, where the stories get richer and the mysteries abound. One story unfolding is with the coastal marine terraces, supporting an ecological staircase with more and more ancient soils, stepwise with each elevation gain travelling away from the ocean. This ecological staircase has been important in understanding how soils develop from bedrock. And, each terrace supports different types of habitat; first coastal terrace grasslands are extremely rare because that’s where we farm…fourth coastal terrace grasslands are rare, too, for other reasons. The higher terraces have 226,000 year old soils, probably the oldest soil communities in North America. The plant diversity of these grasslands has been produced through eras of changing climate and changing animal interactions. Pleistocene megafauna (camelids, mammoths, lions) gave way to more modern grazers (elk on the North Coast, mooo!) and then to very modern livestock: all stewards of the prairies, keeping brush at bay. Native peoples burned and tended this wildscape, a careful examination of even our current landscape will reveal their refined landscape management and agricultural practices.

Another ecological process story that is being told is about North Coast predators. Big cats, pumas, as apex predators are shaping much of the rest of the wildlife communities. Puma presence makes for fewer coyotes, more fox, and all that those shifts mean for bunnies, bobcats, and ground nesting birds. And, puma hunting changes deer behavior, with as yet untold affects on forest understory and streamside plants. My hypothesis is that the big, orange blossomed lily that you can occasionally view (Wilder and Laguna Creeks, for example) should be re-named ‘Cougar Lily’ – indicating the wariness of deer, which would otherwise trim those bouquets to the ground.

Other stories have yet to be told as we explore our curiosity. How important are the processes that move oceanic nutrients upslope to the poorer and poorer, ancient soils? Marbled murrelet carrying fish inland to tall redwood nestlings. Cojo salmon spawning upstream. Nutrient-laden fog drip moving inland. How crucial are these processes to feeding the plants that keep North Coast hills from more quickly eroding? Woodrats, mice, and voles – not just food for the predators, but also architects and builders: how does their nibbling contribute to: keeping grasslands open fields; making flat-topped gnarly trees, or; trimming shrubs to make room for others, creating diverse Manzanita glens. What is missing without grizzly bears tearing at stumps, breaking tree branches for acorns, digging up prairies for gophers?

The North Coast has so much to reveal through its naturally amazing, living systems. It is teaching us how to be indigenous by showing us how we can be better stewards. More people can see these stories by accompanying naturalists on tours, learning to recognize at least a handful of tree and shrub species, and by just plain observing, spending more time outdoors. Challenge yourself to tell your friends new ecological stories about the North Coast: where you see the wildlife, what shrubs are in bloom, what was swimming in the stream, colors of flowers at the beach. Sharing these stories will bring people together, help them cherish what they have, and create dreams about what is possible.

Rare wildflower: the Point Reyes Horkelia

Horkelia marinensis Pt Reyes Horkelia

Licensed under CC: photo by CalFlora user Vernon Smith.  All rights revert to originator.

The Point Reyes Horkelia is a delicate rose-sister with finely fragranced foliage forming drought-hearty dark green patches in California’s remaining coastal prairies. This species, like other close relatives, has strong horticultural value; when only slightly watered in the driest of months, it forms a beautiful, resilient, fire retardant ground cover. White five-petaled flowers form starburst patterned over-stories to a leafy silver carpet. Plants are strong, long-lived microshrubs with deep, woody taproots. Given ideal conditions, mature square meter-sized Pt. Reyes Horkelia clones support extensive root systems, capturing nutrients and rainfall, sequestering carbon, and stabilizing slopes. Across the 25-odd distinct patches of coastal prairie that support this species, Horkelia clones are nurturing increased soil ecosystem diversity.

The Latin, Horkelia marinensis, references Marin County, California, the heartland of the species’ distribution. There are outlying populations elsewhere along California’s central coast.  A few plants live in a meadow on the Moore Creek Greenbelt, more live in prairies near Twin Gates, upper UCSC campus and Wilder Ranch State Park.  More recently discovered populations are at the Bonny Doon Ecological Reserve, San Vicente Redwoods, and on the Cotoni Coast Dairies Preserve.

How rare is this wildflower? Should it be given legal protection under the State or Federal Endangered Species Acts? The criteria are not transparent for awarding threatened or endangered status to this kind of widely distributed plant, which mostly grows in ‘protected’ areas including heavily-used public parks. Some have suggested that if a plant were to have fewer than 16 populations, and if a significant number of those populations are substantially threatened with extirpation, and if a petition were submitted to the government and authored by a legitimate  source…. then perhaps the bureaucracy would rule in favor of conservation.

There are dramatic swings in the annual number of new species protected under State and Federal Endangered Species Acts. Do we have a good system for adequately capturing the urgency of protecting particular species? Experts with the California Native Plant Society agree that the Point Reyes Horkelia is indeed endangered – biologically. These experts routinely reassess their recommended status for species, and make recommendations based both on close scientific observation and the knowledge of experts. Discovery of so rare a species in our hard-pressed midst merits at least an immediate population survey, without which we can’t begin to address its conservation status. Even when this rare species is on public lands there is no government botanist available to collate surveys across the range of the species. And so, surveys and documentation are left mainly to volunteers.

As just such a volunteer, I am pleased to offer what is already known about Pt. Reyes Horkelia distribution in our area. The Santa Cruz County populations of Pt. Reyes Horkelia live on many differently owned and managed lands, with varying management attention. The southern range limit for the species is currently believed to end on the Moore Creek Greenbelt. Santa Cruz City Parks Department has been spending some attention to managing the parks’ beautiful meadows, where the Pt. Reyes Horkelia and other rare wildflowers have been restored through carefully managed cattle grazing. UCSC land also includes a few patches of the species, in moist meadows mainly near Twin Gates, on both sides of Empire Grade in an area known as Marshall Field. The University occasionally does good things for those meadows, like prescribed fire and mowing to maintain native plant species, but the area with this species has been largely neglected for the past decade, so it may be declining. The BLM hasn’t really hit the ground with any kind of targeted meadow management aimed at conserving native plant species on their Cotoni Coast Dairies Preserve. The consortium of land trusts owning the San Vicente Redwoods know about the species being on their land, so they would presumably be careful with any of their timber, fire, or recreational management. The California Department of Fish and Wildlife’s Bonny Doon Ecological Reserve has a single small patch of plants, but no management or monitoring to maintain the species.

Horkelia marinensis Pt Reyes Horkelia

Licensed under CC: photo by CalFlora user Jorg Fleige. All rights revert to originator.

While some of these patches are in good hands, others are under daily threat from disuse or overuse. The impossibility of cooperation across such broad swathes of countryside renders survey work on the holdings of amenable or accessible landowners more urgent. Stunned as we may be that work of this nature is barely funded for the government agencies tasked with oversight of such matters, there are things we can do to help this plant out. For instance, join the California Native Plant Society, which is the most effective native plant conservation organization per dollar invested in the state. Also, every time you hear about plans to increase access, adding trails and visitors, to the meadows of our area…weigh in on native plant conservation with the lands managing entity involved. Mostly, those weighing in are vocal users- mountain bikers, especially…people not inclined to also care about rare native plants. By speaking for, caring about, and investing in our rarest native plant species, you will be contributing to the possibility that future generations will have the chance to experience the fine, rose scented foliage of this beautiful, rare wildflower.

Many thanks to Wes Harman for editorial assistance.

Golden Crowned Sparrow Returns to Central California

GoSp

Bold markings on this golden crowned sparrow indicates a ‘powerful’ individual.

Weary Willie’s distinctive call is waking up our neighborhood for the first time in five months.   We might not have heard them except for the windows being down for the intense heat wave.  Sometime late last week, the first Golden Crowned Sparrows arrived here in Davenport from their migration to British Columbia or perhaps Alaska.

Nicknamed ‘weary Willie’ for their call – “I’m so weary,” – this sparrow is our wintertime friend here, with ~20 bird flocks returning to exactly the same small shrub patches they inhabited last year.  Well, at least SOME of the birds return, and some of those with their young which were born perhaps as far north as the ‘Bering Land Bridge National Preserve.’  Way up north, the a male feeds his mate as she incubates eggs.  Between flying back and forth, making a nest, feeding each other, fledging and raising young, they’ve been very busy since they left.  I’m fascinated with them because of their social structure and their tendency, like me, to be ‘home bodies.’

Bruce Lyon, a professor at UC Santa Cruz has been studying flocks at the UCSC Arboretum.  He finds up to 50% (or more!) of the birds returning in fall migration.  He has confirmed what many have noted – ‘high site fidelity’ – with the Arboretum birds.  Bird banding makes all that possible; I wish I could recognize individual birds well enough to do that from memory.

Individual birds are recognizable, and their plumage can tell you how high on the pecking order they reside.  Lyon has also noted that the size and color of their golden crowns, the patches of yellow on their heads, varies with their status in their flock.  The bigger and more striking the yellow, the more dominant the birds…including yellow patches on females that are dominant over duller males.  Taking the time to distinguish and even name individual birds in our flock is fun and helps me to understand a little of what is going on in the yard.

I have noticed that the birds ride the first winter cold fronts around Fall Equinox, perhaps taking advantage of the winds to help carry them.  I also wonder if they migrate more during the darker moon phases that intersect with those cold fronts.  I understand that many birds migrate mostly at night to avoid predation.  A small group of us sometimes place bets on first rain date as well as first golden crowned sparrow arrival dates.  This year, they came right on time…

Welcome back Golden Crowned Sparrows!