Trouble in Paradise: Migrating Monarch Butterflies Face Declines

Cover photo: © Felix, 2011, some rights reserved.

Learn about the Monarch Butterfly, the threats that contribute to their continuing decline, and ways you can help from your own backyard.

Cover photo: © Felix, 2011, Photo Library (Flickr), some rights reserved.

Quick Facts

  • Monarch butterflies make an annual migration to warmer temperatures, with some populations traveling as far as 3,000 miles.
  • Santa Cruz is one of the monarch overwintering sites in California.
  • Monarchs have faced declines over the past 20 years, and 2018 marked the lowest count in 5 years for the California population.
  • Factors such as loss of flowers, degradation of stopover sites along their migration, and the loss of overwintering habitat in Mexico contribute to their decline.


It was late December when Dan and I packed up our camera gear and set out for Santa Cruz to see the monarchs. Ever the worry-wart, I anxiously clasped and unclasped my hands the entire one-hour drive over. “What if we missed them?”, I asked, eyes wide with potential disappointment as we wound down Highway 17. It was our first time hearing about the incredible journey of this butterfly, and I was avid about witnessing it for myself despite it being towards the end of their migration.

Racing the sunset, we arrived in the Lighthouse Field parking lot and made our way down a field path leading to a small stand of eucalypts. Rounding the a corner on the trail, we were met with a small cluster of trees dripping in orange. Tiny flutters gave life to the bright masses, which were unmistakably made of hundreds of butterflies.

The Journey South

Most people, myself included, will react in disbelief upon hearing that a delicate orange butterfly migrates thousands of miles to escape cold temperatures. “But migration is for the birds!” they’ll think, when trying to picture an insect achieving such a feat. Sure enough, monarch butterflies are the only known butterfly species to migrate in two directions (north and south), and they happen to overwinter in Santa Cruz, just outside of the Bay Area.

This incredible journey is made by one specific generation of butterflies, termed the “migratory generation”. Cooling temperatures, shorter days, and the aging of milkweed, the primary source of food for monarch caterpillars, signal to the butterflies that it’s time to begin the journey south to escape cold temperatures.

There are two populations of migrating monarchs: one east of the Rocky Mountains, and one west. The eastern population, with individuals from places as far as southern Canada, make their journey down to Mexico where they congregate in the oyamel fir forests. For this population of butterflies, the migration can be as long as 3,000 miles. The western population makes their way over to California’s coast, overwintering in locations from Santa Cruz all the way down to San Diego.

Migration Map Epic Migration
Created by Paul Mirocha for Monarch Watch

Relying on navigational cues such as the Earth’s magnetic field and the position of the sun, the butterflies make their long flight. Upon reaching their destinations, the monarchs congregate together and form large clusters on the branches of trees. This allows the insects to retain enough warmth to survive the winter.

Trouble in Paradise

The Western Monarch Thanksgiving Count is a citizen-science project (a scientific study based on data collected by the public) that stands as the longest-running and most comprehensive count in for the monarchs overwintering in California. Citizen-scientists, biologists, and other professionals join forces for a 3-week long effort to count butterflies at multiple sites.

Monarch Butterfly Count
Xerces Society Western Monarch Thanksgiving Count. 2018. Western Monarch Thanksgiving Count Data, 1997–2017. Available at: (For a full list of contributors, see

But lately, the numbers have been grim. The western population of monarch butterflies has been facing declines over the past 20 years, and 2018 marked the lowest count in 5 years. According to one source, 1.2 million butterflies were recorded on a survey two decades ago. The graph above shows the decreasing numbers, and in 2018 a survey using almost the same number of locations recorded just 300,000 butterflies.

A Complex Decline

Many sources have suggested that the loss of the monarch caterpillar’s only food source, milkweed, has been the major contributor of the monarch decline. However, a recent study on long-term monarch population trends conducted by a Cornell University academic suggest otherwise.

Anurag Agrawal, from Cornell’s Department of Ecology and Evolutionary Biology, wanted to take a closer look at all of the monarch population data. Pulling together multiple data sets, he worked with the intent to identify where the biggest hits to the population occurred along the monarch’s migratory route.

Surprisingly, he found that populations trends appear to be doing the best at points where they are relying on milkweed, meaning that milkweed’s decline may not be the only cause of the monarch population decline. Instead, the problem is happening at points during their migration and in parts of their overwintering sites in Mexico. The degradation of sites that they use to stopover along their migration, the lack of sites with nectar-rich flowers to fuel their migratory journey, and the loss of their overwintering forests in Mexico appear to be the main contributors to population loss.

That’s not to say that planting native milkweeds to help the butterflies will be a vain effort – as providing additional resources to the butterflies can never hurt. However, these efforts can be greatly amplified by other efforts as well. Planting habitats for monarchs to feed in your own backyard, only buying FSC-certified wood (Forest Stewardship Council certification, certifying that the wood has come from a responsibly-managed forest and supply chain), and volunteering for monarch counts are all other ways that we can help.

Public education, in particular, can also work to help the butterflies – for that allows us to approach the complex problem on a unified front. With more people aware, we can work together to save the monarchs before they vanish from our coast.

© 2017, Mike Bessler, Photo Library (Flickr), some rights reserved.


Social Attraction: The Story of California’s Common Murres

Cover photo: © 2012, Tim Lenz, some rights reserved.

The story of the decline of a California seabird, and its recovery using decoy birds, speakers, and mirrors.

Cover photo: © 2012, Tim Lenz, Photo Library (Flickr), some rights reserved.

Quick Facts

  • Common murres are seabirds, spending most of their time out at sea in search for food.
  • By nature of being seabirds, murres are especially susceptible to threats to marine environments like irresponsible fishing practices and oil spills.
  • The culmination of improper fishing and oil spills dramatically decreased the population of common murres in Northern and Central California.
  • Social attraction techniques, which work to “trick” birds into returning to a nesting site, were successfully used to restore common murre populations that faced declines.
  • Common murres and other seabirds are still threatened by climate change, which are making El Niño events more intense.


Although tied up in a ponytail, my hair whipped back and forth in the strong breeze along the steps down to the Point Reyes Lighthouse. Despite the wind and the occasional cold gust, the site was rewarding in its incredible views of California’s coast. While hiking, I couldn’t help but catch a whiff that was undeniably seabird in origin. With my interest piqued, I scanned the coastline with my binoculars to find a colony of common murres dotting the white rocks below.

A Population in Decline

The common murre is a sleek and gorgeous seabird found on both coasts of North America. In California, murres form large breeding colonies in areas along the North and Central coast. As a seabird, the common murre spends most of its time on the water. Consequently, its time spent out in the ocean in search for food or resting make the common murre particularly susceptible to population declines from harmful marine fishing practices and marine oil spills.

Image result for gillnet diagram
Gillnet diagram; Source: University of Michigan

The culmination of events such as these led to a serious decline in California’s common murre population. The use of gillnets, a net that forms a large, vertical wall under the ocean surface, led to entanglement and resulting decline of common murres. Oil spills, such as the 1986 Apex Houston spill and the 1998 Command spill, contributed to declines as well, killing thousands of birds and eliminated the population of common murres on Egg Rock at Devil’s Slide in Pacifica, CA.

Social Attraction Leads to a Recovery

The declines that the common murres faced called for action. In 1996, that call was met by the formation of the The Common Murre Restoration Project by the U.S. Fish and Wildlife Service in collaboration with other organizations. The project’s primary goal was to restore the Devil’s Slide Rock population that was wiped out during the oil spill, and increase numbers of common murres and other seabirds across Central California.

This behemoth effort begs us to question — how does one simply restore a population of seabirds? As it turns out, methods to achieve this task have been developed by Dr. Stephen Kress and have proven successful in other bird populations. The method’s idea is elegant: by tricking birds into thinking that other individuals of the same species are already present at a specific location, we can incentivize the breeding birds set up their nests at that location.

These methods are termed “social attraction”, and include an entire suite of different ways to attract breeding birds back to the site. Chick placement at a specific location can work to have the growing birds imprint on the location, causing them to return to that site to breed as adults. The placement of decoys (think the fake ducks used for hunting) and speakers set up to play the calls of the target bird species can work to make it seem like birds of the species are already present at the location, enticing live birds to reside there as well. Mirrors can also be used to attract birds, as they create the illusion of movement and more individuals to birds flying overhead.

A visual of Dr. Kress’s “social attraction” techniques; Source: Audubon

Social attraction has been used in many seabird restoration projects, and has proven  time and time again to be a success (my personal favorites include Project Puffin and the Tern Restoration Project in Maine). Thus, it makes sense that these methods gave new hope to the Common Murre Restoration Project at Devil’s Slide Rock.

For the project, they placed common murre decoys on the island, played common murre sounds from speakers at the site, and placed mirrors around the area with the hopes that these would attract more birds to the site. And the result? The murre breeding colony on Devil’s Slide Rock has been increasing every year since the implementation of the social attraction techniques in 1996. The population in Point Reyes has also increased since the Common Murre Restoration Project began. Thus, the work with common murres off the coast of California is another recorded conservation success story using social attraction techniques.

A Threat Still Looms

Despite the common murre’s population recovery due to conservation efforts, threats to their population still remain.

El Niño events are naturally-occurring phenomena, in which the upwelling of nutrient-rich cold water is reduced relative to “normal” years. Fish depend on this cold water upwelling, as the plankton that they eat are associated with the nutrient-rich waters. El Niño events, in turn, can affect the fish populations which seabirds depend on.

Climate change is disturbing the natural ebb and flow that marine ecosystems experience with El Niño: climate change is linked to more intense El Niño events, making these events much more serious. More serious El Niño events puts more strain on fish populations, and as a consequence puts strain on the seabird populations that rely on those fish. The common murre is just one of those seabirds affected – a call to action for our entire planet to heed attention to the serious danger that climate change poses to all life on Earth.

In light of this, it becomes increasingly important each day to think critically about conservation concerns that our local species are facing – especially in light of the world’s changing climate. That said, it is also important to stop and smell the roses with conservation successes, for hope from these sweet victories are what drive present and future generations of activists.

In that moment at Point Reyes, gazing out at the rocky coast dotted with loud murres, I felt the surge of awe and excitement that comes with a bird that’s made an incredible comeback. I truly stopped to smell the roses, but in this case, it smelled like fish, salt, and seabird.

© 2010, Allen Shimada, NOAA Photo Library (Flickr), some rights reserved.


Nature in the Heart of Silicon Valley: Pearson-Arastradero Preserve

Palo Alto, Ca – The Pearson-Arastradero Preserve offers grassy hills and miles of trails for hiking and dog walking, right in the heart of the Silicon Valley.

Species to Look Out For

About the Park

Palo Alto, Ca – Open Space

Science Spotlight: Restoring Native Californian Grasslands & Oak Habitat

With the settlement of the Spanish came the introduction of non-native grasses to the Bay Area. These non-native grasses, lacking natural predators in their introduced environments, were able to spread rapidly and out-compete native grasses and wildflowers. As a result, 90% of the native habitat has been lost to foreign invaders.

Native oak habitats have also suffered. Spanish settlers cleared large oaks to make the land available for cattle grazing, and the livestock in turn ate many of the oak saplings and acorns. This, along with depleted soil moisture from non-native plants, has contributed to the loss of much of the oak habitat.

Today, local organizations work with Pearson-Arastradero to restore the habitats that were lost. For more information on how you can get involved, check out the Grassroots Ecology volunteer page or the California Native Plant Society volunteer page.

Park History

The area that is now Pearson-Arastradero was once a working ranch. In 1976, the Palo Alto City Council purchased the land to protect it from developers. They have been acquiring more land for the preserve since, and it now has a total of 622 acres.

Visit the Park

Please note that there is no entrance fee to enter the park. Dogs are allowed on leashes.

When visiting, we recommend taking the Juan Bautista de Anza trail down to see Arastradero Lake. There, you can find a great assortment of waterfowl, song sparrows, and the occasional black phoebe. When walking along the grassy trails, be on the lookout for American kestrels, western bluebirds and lesser/American goldfinches.

Here are some helpful resources to help plan your visit:



Witness Cool Sandstone Formations at Castle Rock State Park

Los Gatos, Ca – From sandstone to redwood trees, Castle Rock State Park is a Bay Area hiking spot that you don’t want to miss.

About the Park

Los Gatos, Ca – State Park

Science Spotlight: Sandstone at Castle Rock

During our visit to Castle Rock State Park, we were captivated by the carvings of sandstone that lined the park’s trails. The erosion in the sandstone has created interesting patterns over time, which are awesome sights along the hike.

The sandstone at Castle Rock is made mostly of large-grain sand held together by calcium carbonate “cement”. Sandstone naturally has thin cracks along the formation of the rock. Slightly acidic rainwater (rain is made slightly acidic because of water’s reaction with carbon dioxide in the air) is able to penetrate the stone through the cracks, dissolving the calcium carbonate as the water moves into the rock during the wet season.

During the dry season, the water on the inside of the rock is drawn to the surface, bringing along the dissolved calcium carbonate with it. This movement weakens the interior of the rock and strengthens the exterior of the rock, resulting in erosion patterns that can look like pockets. Over time, this process can also produce large caves. As you hike along Castle Rock, be sure to keep your eye out for such formations.

For more information on Castle Rock Geology, feel free to check out this article by the Portola and Castle Rock Foundation!

Park History

The area that we recognize as Castle Rock State Park used to be a network of trails used by the Ohlone people to transport goods from the coast more inland.

The California Gold Rush was the first major source of transformation for the park. Similar to the story of Huddart Park, Castle Rock State Park became a source of lumber for the booming population in the San Francisco Bay Area. Farming in the area also impacted the habitat as orchards were planted to sustain the people living there.

Locals who loved the landscapes around the area began to purchase small plots of land to be enjoyed by the public. In 1968, the area was designated as a State Park after the land was donated to the state by the Sierra Club and Sempervirens Fund.

Visit the Park

Please note that there is an $8 parking fee. Dogs are not allowed in the park.

We recommend checking out the waterfall viewing platform and Goat Rock during your visit. Be sure to bring a camera to take photos of the beautiful sandstone formations!

Here are some helpful resources to plan your visit:


See Relics of the Bay Area’s Lumber Past at Huddart Park

Woodside, Ca – Come witness the beauty of redwood trees at what used to be a lumber operation to supply the greater Bay Area.

Species to Look Out For

Coast Redwood circle.png

Coast Redwood

About the Park

Woodside, Ca – San Mateo County Park

Science Spotlight: Coast Redwoods at Huddart Park

Coast redwoods are the tallest trees on Earth – and they live right in our backyards.

The coast redwood is one of three remaining redwood species on the planet. This tree only grows along the Pacific coast, from Big Sur up north to the southern part of Oregon.

The old growth coast redwoods (trees that have been left undisturbed for long periods of time) are far fewer than what they used to be 150 years ago. The California Gold Rush of 1848 brought about huge population increases in the San Francisco Bay Area. To meet the growing demands for wood to supply developments, settlers turned to lumber from coast redwoods. It is estimated that only 5% of the old growth coast redwood trees remain today.

Map of the historic and existing ranges of coast redwoods. Source: Save the Redwoods League

Park History

The area that is now Huddart Park was once in the middle of large redwood lumber operations, with 5 operating sawmills around the park. It has been over 100 years since the logging, giving time for new growths of redwood trees.

In 1935, the wealthy lumberman James Huddart donated 900 acres of the area to the County of San Francisco. The land has changed hands a few times since, and now is under the ownership of the County of San Mateo.

Visit the Park

Please note that there is a $6 fee to enter the park. Dogs are not allowed.

Here are some helpful resources to help plan your visit:


The Geology Rocks at Rodeo Beach South

Mill Valley, Ca – Need a secluded spot to relax? Check out Rodeo Beach South, a short hike through a beautiful landscape to a beautiful beach. Plus, it’s right near Point Bonita, making this an easy hiking double feature.

About the Park

Mill Valley, Ca – Region of the Golden Gate National Recreational Area

Science Spotlight: Rodeo Beach Geology

When I walk along California’s beaches, I tend to be so captivated by the landscapes around me that I find it easy to ignore the beauty beneath my feet. While every beach has some beautiful geological history to offer, Rodeo Beach stands unique amongst other beaches. Its beautiful, coarse, and pebble-dotted sands reflect a rich geological history.

Remember learning about the 3 major rock families when in elementary school science? As a refresher, rocks can be categorized based on the way in which they are formed. The three rock families are igneous, sedimentary, and metamorphic rock – and it just so happens that you can find all three on Rodeo Beach, making it a gem in terms of California geology.

Looking at the beach geology more granularly, one source reports that Rodeo Beach sands are composed of the following: red and green chert (about 55%), volcanic rock fragments such as pillow basalts (about 30%), lesser amounts of graywacke sandstone (about 10%) and finer mineral grain, such as feldspar and hornblende (about 5%).

Carnelian, although representing a small percentage of the rock composition, is another notable find on Rodeo Beach. These semi-precious gemstones are bright to reddish-orange in color. These beach gems are formed when small pockets, or vesicles, of silica appear within cooling lava. Years of collecting have negatively impacted the amount of carnelian found on Rodeo Beach, so be sure to refrain from collecting.

© David Abercrombie, 2014, Flickr Album, some rights reserved.

Visit the Park

Please note that there is no entrance fee to enter the park. Dogs are allowed on leashes.

We recommend visiting the southern tip of Rodeo Beach since it’s a skip, hop, and a jump away from Point Bonita. Regardless of the area that you visit, be sure to keep your eyes peeled for shorebirds dotting the beaches, mats of invasive ice plants, and the mosaic of different rocks that make up the sand.

Here are some helpful resources to help plan your visit: