Bay Area Bird Identification: Least Versus Western Sandpipers

Cover photo: © David Ledig / U.S. Fish and Wildlife Service, 2006, some rights reserved.

Least or western sandpiper? Check out our compilation of identification knowledge to help you decide between the two species!

Cover photo: © David Ledig / U.S. Fish and Wildlife Service, 2006, some rights reserved.

When studying shorebird identification, I often found myself scratching my head – especially when it came to identifying two common, diminutive Bay Area sandpipers: the least and western sandpiper.

Peering through my binoculars at large groups of tiny peeps, my mind would second-guess itself: Those look like dark legs, but then again it is awfully muddy… 

For those of you that may also be scratching your heads on the other side of your bins, I’ve created this post as a compilation of identification knowledge that helps me most when discerning between the two species.

I’ve separated the article into two birding scenarios: observing a group of birds that looks like the same species (of least or western sandpipers) or observing a mixed-species flock in which you have narrowed down the species to least or western sandpipers.

If you see a group of birds that looks like the same species of either western or least sandpiper:

Clue 1: Check out those legs.

The first field mark that I tend to go for in the least versus western species diagnosis is leg color. Western sandpipers have black legs, whereas least sandpipers have yellow legs.

Yet it wouldn’t be as fun if it were that easy. As nature will have it, these small shorebirds are often foraging up to their legs in water. Also, the muddy habitats that they dwell in make it easy for mud to cake on their legs – making least sandpiper’s mud-caked leg look deceivingly like a pair of western sandpiper legs.

Least sandpipers
Least sandpipers; Photo © Roy W. Lowe / U.S. Fish and Wildlife Service, 2011, some rights reserved.

Clue 2: What kind of habitat is the bird in?

As mentioned by Joe Eaton in his clever Bay Nature article “Meet The Smallest Sandpipers of the San Francisco Bay“, a tip for discerning between least and western sandpipers is to look at the habitat that you see the bird in.

Western sandpipers will often be found near the edge of water. Least sandpipers are more likely to be in vegetated habitat on ground further away from the water’s edge.

That said, it is important to note that mixed-species flocks are not uncommon – so be sure to pay close attention to the birds’ field marks.

If you see a mixed-species flock and have narrowed the species down to least or western sandpipers:

Clue 3: If the two species are side-by-side, also compare their sizes.

The “least” sandpiper, true to its name, is smaller than the western sandpiper – making identification a bit easier if the two birds are side-by-side.

That said, things become trickier when the species is being looked at on its own. For this reason, I would suggest relying on some tips mentioned previously to make a stronger case in your identification.

Western sandpipers
Note the heavier, more blunt-tipped bills on these western sandpipers when compared to the leasts in the photo above. Photo © Peter Pearsall / U.S. Fish and Wildlife Service, 2015, some rights reserved.

Clue 4: If the two species are side-by-side, compare their bills.

Western sandpipers have longer, thicker bills with a more blunt tip than the bills of least sandpipers. If you have the chance to compare the birds side-by-side, take note of how the western sandpiper’s bill also appears more “droopy” than a least sandpiper’s.

(Bonus): If you are surveying for eBird or another citizen science program, when in doubt just record the bird as “sp”.

eBird’s citizen science data contributes to research worldwide. Thus, it’s important to report exactly what we see and discern. This means that if you are in doubt, it’s better to err on the side of caution and report a “sp.” bird rather than guess just to settle on a species in your report.

There’s no shame in admitting that you weren’t able to tell the exact species identity – you are just doing your job as a careful and responsible citizen scientist!

6067659785_25794bc470_o.jpg
Which sandpipers are we looking at? Answer is at the bottom of the page! Photo © Roy W. Lowe / U.S. Fish and Wildlife Service, 2011, some rights reserved.

Have any tips of your own? Comment below to add your take on deciding between least and western sandpiper!

Resources to Learn More

 

 

Answer to the photo above: least sandpipers! 

Bay Area Science: An Interview with a Kelp Biologist

Meet Sara Gonzalez, a kelp biologist from the University of California, Santa Cruz.

Gonzalez_Sara_18_Logo
A view of the Pacific shore from Santa Cruz, Ca. Note the giant kelp floating on the water’s surface in the distance.

Gulls cried in the distance as we walked along the shore at Natural Bridges State Beach. The air was crisp with a twinge of salt. We had passed numerous brown mounds of kelp when Sara excitedly pointed to a kelp mass strewn on the beach closer to the water’s edge. We found just what we were looking for: giant kelp, Sara’s primary study species.

Sara knelt down beside a piece and picked up one of the bladesthe kelp’s leaf-like structures.

“You can see the really deep corrugations here, and the blade’s serrated edge.” She pointed to the corrugations, or grooves, carved into the kelp’s blade. She gently traced her finger along the serrated edges as I watched intently, realizing I would have missed these delicate details had I not been with Sara.

Gonzalez_Sara_10_Logo

Giant kelp is widely distributed around the world, found along the coast of North and South America, Africa, Australia, and beyond. Distinct geological regions are home to giant kelp populations that look vastly different – despite being the same species.

“Some of these forms are so distinct that they used to be classified as separate species,” Sara explained. “Now they are termed ‘ecomorphs’ of the same species.” Different kelp ecomorphs, or individuals of the same species with different physical characteristics, vary in the form of their blades and the structures they use to anchor themselves to the ocean floor.

Sara Gonzalez is a graduate student in the Department of Ecology and Evolutionary Biology at the University of California, Santa Cruz. Previously, she studied biology at Cornell University. Trading upstate New York’s bitter winters for warmer weather and sandy beaches, she came to Santa Cruz to study kelp with Dr. Pete Raimondi.

Sara’s work with kelp began during a Fulbright Scholarship project in Chile. There, she collaborated with other marine researchers at the Pontificia Universidad Católica de Chile to study the influence of nutrients from fish excrement on kelp growth. I imagined her on the incredible Chilean coast studying its marine life, acquainting herself with the landscapes praised in poems by the famous Pablo Neruda.

While collaborating with Chilean academics studying kelp, Sara realized how embedded kelp is in today’s society as a natural resource. Kelp is harvested for its alginates, a polysaccharide found within the cell walls of all brown algae. When alginate combines with water, it forms a thick gum-like texture, which can be used in products ranging from cosmetics, daily-use items such as toothpaste, and foods such as ice cream.

“It was an interest that grew over time – being around kelp, and talking to people about kelp all the time. I got really excited about it,” Sara said, smiling and looking out towards the water.

Gonzalez_Sara_7_Logo
Sara examining kelp on the beach of Natural Bridges State Beach.

Kelp is a foundation species, meaning it plays an important role in its community. It also forms an entire ecosystem: the kelp forest.

“The high productivity of the kelp forest and varied physical structure from the base to the canopy provide the foundation to support a diverse array of life, including many commercially and recreationally harvested species such as kelp bass, several species of rockfish, and the kelp itself,” Sara explained.

Organisms, ranging from invertebrates to fish to mammals, rely on kelp forests as a place to live, forage, and reproduce. Kelp forests also protect shorelines from erosion by creating drag against waves coming to shore.

Sara’s time in Chile piqued her interest in the morphological differences between Californian and Chilean kelp. This interest grew into a well-formed project as a graduate student. At Santa Cruz, she is studying the environment’s role in determining the kelp ecomorphs and its effects on the production of alginate.

However, today, we were two just two naturalists combing the beach shore.

We approached another mass of kelp, flushing a swarm of small insects as we knelt down beside it. Sara, ignoring the insects, reached down her hands to pick up a kelp mass the size of a soccer ball.

Gonzalez_Sara_5_Logo
A kelp holdfast, held by Sara.

“This is the holdfast,” she explained, turning over the ball, which appeared to be a mass of root-looking structures. “It’s composed of haptera, which are these root-looking things.” She pointed out the network of twisting haptera, growing tightly together in a pattern which resembled the creases of a brain.

On our coast, giant kelp forests grow up to 50 meters from the ocean floor, eventually reaching the water’s surface.

“As it grows, the kelp forms more and more of these haptera, until you end up with this big, netted mass of them.” Sara slowly turned over the holdfast for me to see, pointing out the layers the haptera formed. Despite its resemblance to a mass of plant roots, she explained, a kelp’s holdfast doesn’t act like a root system at all. Rather, it’s used by kelp to anchor itself to substrate. She carefully placed the holdfast back near the pile of kelp blades.

Over the course of our walk along the beach, we encountered 3 different species of kelp: the giant kelp with its densely grooved blades, the chain bladder kelp with its line of bubble-like protrusions, and the feather boa kelp, which looked, not surprisingly, like a long feather boa.

However, our giant kelp specimen was by far the most physically impressive. Scientifically, giant kelp is equally astounding: it is one of the fastest-growing plants in the world, accumulating 12 to 18 inches of growth per day. Their high growth rates make kelp forests one of the most biologically productive communities – comparable to tropical rain forests.

Moving forward, Sara plans to continue her kelp studies by conducting a series of experiments. By rearing kelp in the lab and simultaneously planting them in the ocean, Sara will be able to elucidate the importance of environmental versus genetic factors in kelp morphology and alginate production.

Sara’s work in Chile also shed some light on the importance of nitrogen in fish excrement for kelp growth, and its role in reducing blade decay. These preliminary results prompted Sara to focus on the effects of ammonium on kelp – being the nitrogen product from fish excretion, after the ocean’s pH conditions react with the ammonia from the waste. Less is known about ammonium’s effects on kelp when compared to its close chemical relative, nitrate.

“In parts of California, there are times of the year when nitrate levels are reduced, so it is important to understand the potential contribution of fish-derived nitrogen, especially as oceanic conditions in the future are likely to change,” Sara explained.

We continued down the shore, eventually reaching a rockface with shallow pools carved into it. Inside the pools, anemones dotted the edges like flowers, their tentacles spread out like delicate sea petals. Around the pools, masses of washed-up giant kelp spread out like carpets on the rocks.

I thought of the kelp’s holdfast: its dense network of haptera forming a stronghold to the ocean floor as the kelp grows towards the water’s surface. Then, I thought of Sara. Her ideas seemed to grow in an analogous way, forming a dense network of enthusiasm and curiosity to anchor her as she reaches towards the answers.

We returned to the beach and meandered back towards my parked car, absorbed in our conversation as gulls flew overhead.

Gonzalez_Sara_4_Logo
Footprints in the sand along Natural Bridges State Beach.

If you are a scientist living in or around the Bay Area and are interested in an interview, feel free to contact bayareanaturalist (at) gmail.com.

5 Ways Birdwatching Has Changed My Life

There are very few hobbies that I can say have changed my life for the better, and birding is at the top of that list. Here are just a few ways that birding has influenced me.

I have many hobbies that have enriched my life: reading, cooking, and dancing hula all come to mind as interests that make me feel happy and fulfilled. That said, there are very few hobbies that I can say have changed my life for the better. Here are just a few ways birding has influenced me.

1. Birdwatching taught me how to pay attention.

Birding has completely transformed my day-to-day activities by teaching me how to pay attention. While birding has allowed me to further develop my attention span, it has also taught me how to integrate nature into my day-to-day activities by simply paying attention.

Take walking from your parked car to a building as an example. Before I learned the sights and sounds of individual bird species, a walk from my car was just another task. Learning how to watch birds has flipped an irreversible switch in my mind, turning every moment outside into an opportunity to see or hear new things.

Today, even when doing something as simple as watering my plants outdoors, I passively pay attention to who’s around. Dark-eyed junco hopping underneath my gardening shelves, looking for spilled seed. House finch singing from a perch on the ornamental tree across the street. It’s an incredible gift that I’m grateful to have learned.

2. Watching birds got me to spend more time outside.

I’ve always loved the outdoors, but birding has presented me with the incentive to explore as many new habitats as possible, in hopes of observing more bird diversity.

Since I’ve begun birding, I’ve travelled to habitats ranging from rocky seashores to the edges of lush agricultural fields in search of a particular species. I’ve gotten to know a diversity of places, thanks to the journeys that birdwatching has brought me on.

10550845_838073406204265_3951027189586661986_n
Birding on the rocky shores of the Isles of Shoals, off the coast of Maine and New Hampshire.

3. Birds were a gateway to learning about other incredible wildlife.

Birds, like all other life, interact with a myriad of other species in their day-to-day activities.

As an avid birdwatcher, you sometimes can’t help but wonder who else is in the picture as you’re watching a particular bird. What kind of shrub is that California towhee scuttling under? What kind of plant is that song sparrow using as its singing perch? What kind of mammal did that red-tailed hawk just snatch up? 

These are common questions running through my mind as I watch birds, and are all musings that prompt me to jump on my computer once I’m back home to do some research. This cycle has led me to discover the names and life histories of many non-bird species, thus allowing me to become a more well-rounded nature lover.

Baylands 1 Mark.jpg
Shorebirds gather at the Palo Alto Baylands Nature Preserve.

4. Birdwatching has brought me to an amazing, tight-knit birding community.

Joy loves company, as proven time and time again in the friends that I’ve made through birding. Whether I’m living in the San Francisco Bay Area, upstate New York, or in the suburbs of Australia, there isn’t a single place that I haven’t found a tight-knit and supportive group of birdwatchers and nature enthusiasts. By joining local birding email listservs, local Audubon chapters, or even visiting a local nature center, I’ve met many new, welcoming faces.

5. Watching birds has allowed me to deepen my knowledge and involvement in local conservation issues.

Being a part of the birding community also meant joining forces with incredible advocates and leaders in environmental grassroots movements. Because of my involvement in the birding community, I’ve been able to learn more about important local conservation issues and projects that impact the habitats of native species.

In the Bay Area alone, I’ve been exposed to the wonders of wetlands restoration for native species, the declines of raptors such as American kestrels and burrowing owls, and the impacts that even a single crumb left behind at a campsite can have on the dynamic between Steller’s jays and marbled murrelets. While I would have likely read about these issues before becoming a birder, being an avid birdwatcher brings you that much closer to the battlefront of local conservation concerns.

(Bonus) 6. The excitement doesn’t stop at watching birds.

Birding has brought me happiness beyond just watching birds – it has allowed me to find other outlets for my passions, whether it be science education and outreach, science writing, photography, or travel.

Letting birds into my life has given me an incredible sense of purpose and belonging, and I can only hope that it will do the same in yours. Cheers to your next (or first!) birding adventure.

1553304_785900691421537_963546150457126999_o
Me doing a bird banding demonstration with an American goldfinch to a group of young girls at the Cornell Lab of Ornithology’s Migration Celebration.

For more information on local bird species in the Bay Area, check out our wildlife resources on birds.

Logging, Crumbs, and Lost Fish: The Story of the Marbled Murrelet

Cover photo: © Tom Benson, 2014, some rights reserved.

Did you know that there’s a seabird that builds its nest high up in redwood trees? Learn about the marbled murrelet – from their breeding biology to what we think could be causing their population declines.

Cover photo: © Tom Benson, 2014, Flickr Photo Album, some rights reserved.

Quick Facts

  • Marbled murrelets are seabirds that venture inland to build their nests high up in redwood trees.
  • The health of coast redwood forests affects marbled murrelet populations, since murrelets need redwood forest habitats to breed.
  • Despite considerable conservation of redwood forests, marbled murrelet numbers are still declining by 4 percent annually.
  • Scientists have found that predation by Steller’s jays attracted to campgrounds by human food is affecting marbled murrelet numbers.
  • Since murrelets are seabirds, the health of our oceans could also be impacting marbled murrelet populations.

 

The Mystery of the Marbled Murrelet

Our story begins with a mystery.

Marbled murrelets are robin-sized seabirds that are closely related to puffins and murres. As is the norm for other seabirds, scientists expected the marbled murrelet to nest in large colonies along the rocky coast. Yet no such breeding colonies of marbled murrelets were found, despite the habits of their close relatives. The nesting place of the marbled murrelet remained an unsolved mystery to ornithologists in North America for over a century.

This changed in 1974, when a worker performing maintenance at Big Basin State Park discovered a lone nest high up in a redwood tree. The nest contained a single chick, which strangely had webbed feet. He snapped a photo that was later identified by bird experts as a marbled murrelet youngster. The mystery of the marbled murrelet nesting place was solved.

Defying all expectations of a seabird, these clever nesters fly 20 miles inland to construct nests high up in the cover of redwood trees. With this discovery, the marbled murrelet became the most recent bird species to have its nest found in North America.

Big Basin SP 1 Logo
A coast redwood towering over the trail at Big Basin State Park, the site of the first documented marbled murrelet nest. Old-growth coast redwoods are the nesting sites of marbled murrelets.

Logging and the Loss of Murrelets

The California Gold Rush of 1848 brought steep human population increases to the San Francisco Bay Area – and with these population increases also came a huge demand for lumber. Settlers turned to the redwood stands along California’s coast for their supply. The irresponsible logging stripped most of the old-growth redwood forest from our coastline. It is estimated that only 5% of old-growth coast redwood trees survived logging.

Coast redwoods are critical to breeding marbled murrelets. Thus, the declines of redwood forests were closely intertwined to declines in marbled murrelet populations. The low murrelet numbers recorded off our coasts resulted in their listing as threatened under the Endangered Species Act in 1992. In California, they are state-listed as endangered.

The fate of the murrelets, along with other calls for the reduction of logging in the northwest, led to the 1994 Northwest Forest Plan under President Clinton. The plan protected 9.7 million hectares of old-growth forest along the coast of California, Oregon, and Washington.

Despite the protected breeding habitats, scientists monitoring murrelet populations still found that their numbers were declining. The population around California, Oregon, and Washington is continuing to decline by as much as 4 percent per year.

Crumbs, Jays, and Predation

A study at Redwood National and State Parks discovered one potential cause of the murrelet declines: predation by other birds, namely Steller’s jays.

Steller’s jays are crested blue and black birds found along the west coast of North America and south into Mexico. They are corvids, belonging to the same family as crows, ravens, and other jays. In addition to their diets of plant matter and insects, they will eat the eggs and young of other bird species.

Image result for crumb-free sign marbled murrelet stellers jay sign
A common sign at campgrounds, featuring a Steller’s jay and a warning to clean up all traces of food. Source: Save the Redwoods League.

Steller’s jays are common at campgrounds, as their varied diet is supplemented by leftover food and crumbs from humans. These “crummy” areas attract jays and increase their density, thereby increasing the chances of Steller’s jays finding and predating the nests of marbled murrelets.

Public education programs are in place to decrease the amount of food left behind by humans. The initiative’s goal is to decrease the number of murrelet predators attracted to a given area. Signs are present in parks, warning people that food waste (even as small as a single crumb) has the potential to impact marbled murrelets.

Ocean Threats Still Loom

Scientists still don’t have all of the answers to what’s causing the murrelet population decline.

One factor affecting their numbers could be the availability of food off our coast. A study in Washington found that 80% of marbled murrelet nest attempts failed due to issues relating to low prey availability.

We do know that more frequent and intense El Niño events caused by climate change are negatively impacting fish populations. El Niño is a naturally-occurring phenomenon in which the number of upwellings of nutrient-rich cold water is reduced relative to “normal” years. Plankton, a main food source for fish, rely on the nutrients from the upwellings. With no plankton to eat, the fish populations (and the seabirds that depend on them) can be negatively impacted.

What does this mean for the marbled murrelet? Our efforts on land can be executed flawlessly, but the dual-lifestyle of this enigmatic seabird makes it so that their populations can still be harmed by threats to our oceans.

Stories such as these bring to light the importance of protecting as many diverse areas as possible. A holistic approach to conservation is necessary to save species that live such diverse lives.

Pacific Logo.jpg
A view of the Pacific Ocean off the coast of California.

Sources:

Essentials in My Outdoor Backpack

Whether I’m getting ready for a day hike or a long walk to do some birding, I make sure that my backpack has the essentials. Here’s a list of things that I like to keep handy at all times, as well as a few optional things!

Whether I’m getting ready for a day hike or a long birding walk, I make sure that my backpack has the essentials. Here’s a list of things that I like to keep handy at all times, as well as a few optional things!

Health & Safety Items

Extra water

If there’s one thing I’ve learned to be careful about, it’s making sure to always pack extra water! Just in case you take a wrong turn on your hike that extends the trip, or the weather ends up being a crazy heat storm, it never hurts to have some extra water on hand.

First aid kit

To help with first aid preparedness, I bought a small travel-sized kit that fits right in my backpack. In case you’re looking to downsize on the amount of room your items take up, it never hurts to grab a Ziplock bag and throw in some band-aids, gauze, a pack of electrolytes, a couple of Q-tips, Neosporin, and a pack of ibuprofen.

A map

It’s always a good idea to plan your route ahead of time. In addition to this, I like to print or pick up a map before my hike so that I’m prepared if I make any wrong turns.

A snack

Just in case I need a little boost on the trail, I like to have an individually-packaged snack on hand. My favorites include small bags of trail mix or Clif Bars.

Sunscreen

This one goes without saying. If you don’t want to end your hike looking like a lobster special, I like to apply before and bring some along just in case. To minimize on the amount of things you’re carrying, I find it’s helpful to buy a travel-sized lotion container and throw some sunscreen in there.

Hat

Depending on the season that I’m hiking, I like to pack either a baseball cap or a beanie.

An extra warm layer

No matter the forecast, I like to be prepared just in case there’s a weird lapse in the expected weather. Try packing a light shell that’s easy to fold up and store in your bag.

One pair of extra socks

You’re on your third mile of a ten-mile hike and you’ve stepped in a puddle deep enough to get around your waterproof shoes. Now what? Extra socks, of course!

Field Observation Items

Waterproof notebook

My favorite outdoor notebook is a Rite-in-the-Rain spiral-bound notebook. They’re a bit on the expensive side, but well worth it in case your bag gets wet. These little guys have survived many disasters with me over the years – from having an angry herring gull poop right in the middle of my page to my book being dropped in a mud puddle while stalking superb lyrebirds.

Pencil or waterproof pen

This goes along with the waterproof notebook. Pencils will work flawlessly in the Rite-in-the-Rain notebooks. However, if you’re looking for something a little more fancy, I would suggest the waterproof pen made by Rite-in-the-Rain. Again, they’re on the expensive side, but my pen has lasted years and is well worth it.

Field guide

I love looking up what species I’m observing right in the moment. To help with this, I pack a local field guide. My favorites include Sibley’s mini-sized Guide to Birds of Western North America. The Audubon Society also has put out a number of amazing pocket-sized guides to wildflowers, butterflies, and trees of North America. If you’re looking for deals, libraries will often have monthly book sales where you can pick up heaps of guides like these for 50 cents to a dollar each.

Plastic ruler

I love bringing flexible, bendy rulers that have a plastic coating so that they’re also waterproof. These help in case you need to measure something you find in the field.

Watch

Good field observations have the time and date that they’re recorded! Never miss out on a good field note by keeping a watch handy.

Optional Items

Multi-tool

Okay, I’ll admit – I’ve only used my Leatherman multi-tool out in the field a handful of timesBut each time it saves the day so drastically that it’s well worth carrying around.

Compass

I love to know generally which direction I’m headed, just in case I end up off-trail. I especially like the compasses with glow-in-the-dark headings. My favorite one comes attached to a ruler!

Camera

As you can tell, I love shooting photos of wildlife and landscapes while out on my outdoor adventures. There are some relatively affordable digital SLR cameras out there, too! I recommend Canon’s Rebel series.

Binoculars

What kind of birdwatcher would I be if I didn’t carry around my trusty binoculars all the time?

Sudden Oak Death’s Grip on California Forests

Oak trees have been in danger in California since the mid-1990’s, and researchers are now predicting a grim future for California’s emblematic tree. The killer, termed “Sudden Oak Death”, has killed an estimated 3 million trees since its introduction to California.

Quick Facts

  • Sudden Oak Death is caused by a fungus-like pathogen. It is fatal to many California-native oak species.
  • Since its introduction to California, the pathogen has killed an estimated 3 million trees.
  • Scientists have concluded that the pathogen’s spread in California is too great to completely eradicate it. Rather, management of the disease in localized areas is suggested to be our best option.

 

A Fatal Pathogen and Its Spread

Something weird began happening to California’s oak trees in the mid-1990’s.

Trees were plagued with a sudden onset of dying leaves and trunks that “bled” dark-colored sap, and locals concerned about the sudden tree deaths reported their observations to specialists.

The pathogen causing the symptoms was identified in 2001 as Phytophthora ramorum, a fungus-like species that infects plants. P. ramorum arrived to California by infested rhodendron plants. The fungus spread across the United States through shipments of nursery plants before it could be detected. It is spread through spores, which can be carried by rain, wind, and infected soil.

The symptoms exhibited by infected plants vary by plant species. Some plants can be infected with the pathogen and not have symptoms serious enough to be fatal, allowing the plants to continue living and spread spores from the pathogen as “carriers”. The California bay laurel is a well-known carrier, since its symptoms are limited to spots on some parts of the leaves and diebacks of twigs.

P. ramorum is known to cause death in a number of oak species, including coast live oak, Shreve oak, and California black oak. P. ramorum is also known to infect a relative of oaks, the tanoak. The main symptom of infected trees is a canker on the trunk, with blackish to reddish sap that “bleeds” from the sore. Infected trees take an estimated 2 years to die from the pathogen itself; however, other pathogens and insects readily infect the already-sick trees and speed up the tree’s death.

A Disease With Far Reaches in California

Since its introduction to California in the mid-1990’s, Sudden Oak Death has killed an estimated 3 million trees along the coast from Big Sur to Oregon. The effects of this disease also go beyond just the deaths of trees – trees that have died from Sudden Oak Death are dangerous fuels for California wildfires, a threat that has become more prominent as we face the effects of climate change.

Management practices have focused on the identification, quarantine, and removal of infected plants as a way to stop its spread. Public education initiatives have also focused on educating California residents on how to avoid spreading the disease, through practices such as sterilizing pruning tools and washing off equipment, tires, and shoes that have come in contact with infected soil.

Predicted spread of the sudden oak death epidemic through California, 1990–2030
An image from Meentemeyer et al. 2011 showing the predicted spread of Sudden Oak Death from 1990 – 2030, based on the assumption of similar weather conditions to those in California from 1990 – 2008.

Despite California’s efforts, a recent study (Meentemeyer et al. 2011) conducted by scientists from Cambridge, the University of California at Davis, and the University of North Carolina has concluded that completely eradicating the disease from California is not possible. The sheer number of trees infected makes it impossible to rid the state of the disease or stop its spread.

Instead, the study suggests that management should focus on the restoration and treatment of small, local forests as the most practical and cost-effective option. One such study focusing on removing dead and diseased trees is currently being conducted around Bolinas Ridge, giving us hope for the development of best management practices moving forward.

Sources