A San Francisco Butterfly: The Variable Checkerspot

Cover photo: © Jamie Chavez, 2013, some rights reserved.

Learn more about the small butterfly that’s making a comeback around the San Francisco Bay Area.

Cover photo: © Jamie Chavez, 2013, Flickr Photo Album, some rights reserved.

The Presidio’s population of variable checkerspots became locally extinct in 1978.

Variable checkerspots are a part of a program working to reintroduce native species back to the Presidio in San Francisco. The Presidio’s checkerspot population became locally extinct in 1978 due to the loss of habitat. Park restoration efforts are currently working on the Presidio’s native habitats, resulting in 50 acres of native habitat restored thus far. With the hopes of bringing the butterflies back, 1,500 caterpillars were collected from other parts of the Bay Area and reintroduced to the Presidio in 2017.

If successful, the Presidio will become one of two areas in San Francisco that hosts the variable checkerspot butterflies (the other at Laguna Honda Reservoir). The primary cause of their decline in the area has been the loss of habitat across the city. With efforts such as those at the Presidio, we can hope that we’ll be seeing more of this beautiful butterfly.

Variable checkerspot caterpillars are spiny, and the butterflies are black with checkers.

Variable Checkerspot caterpillars are mostly black, with light dots that form bands along their body. They are covered in black and orange spines.

Butterflies are mostly black-brown, with yellow and orange checkers. Their wingspan is 1.25 – 2.25 inches.

Variable Checkerspot Caterpillar
Variable Checkerspot caterpillar on an English Plantain at Purisima Redwoods Preserve

Variable checkerspots live on the west coast of the U.S.

Variable Checkerspots can be found along the Pacific Coast,and as far inland as Wyoming and Colorado. They prefer chaparral habitats (semi-arid areas composed of mostly shrubs), open forest areas, and alpine tundras.

Variable checkerspots use many native and non-native plants for food.

Caterpillars will use beeplant, Indian paintbrush, snowberry, honeysuckle, monkeyflower, English plantain, and many others as host plants. Adults will feed on nectar from California Buckeye, Squawbush, Yerba Santa, and thistles (to name a few).

Resources to learn more:

Nature’s Majesty: The Giant Sequoia

California is home to the largest tree on the planet – a giant sequoia named the General Sherman Tree. Learn about this massive tree species, its old age, and how it inspired the National Park Service logo.

Giant sequoias are the largest trees on Earth.

Giant sequoias are truly giants – they can grow to heights of about 300 feet and their trunks can reach diameters of about 30 feet. While some tree species can match the giant sequoia by either height or diameter, no other species can beat both. Because of this, giant sequoias grow to be the world’s largest trees.

Giant sequoias stop growing in height over time; however, they are always growing around the trunk. The largest tree on the planet, General Sherman, is a giant sequoia at Sequoia National Park. Each year, it grows enough wood around its trunk to be equivalent to a large tree of a different species.

Giant sequoias live to be thousands of years old.

Giant sequoias live for thousands of years. The oldest giant sequoia is estimated to be 3,210 years old.

To age a giant sequoia, scientists count the tree rings from an intact trunk of a fallen tree. Using the information from the trunk, scientists can then estimate the ages of standing trees that are a similar size and that grew in a similar environment.

Giant Sequoia 5 Logo
Giant sequoia in King’s Canyon National Park

Giant sequoias are only found in California.

Giant sequoias have a very restricted range, meaning that they only grow in a small area on Earth. Giant sequoias are only found on the western side of the Sierra Nevada mountains in California, along a short stretch of about 250 miles. They grow at elevations of 4,000 to 8,000 feet.

Giant sequoia seeds have a one in a billion chance of becoming an adult tree.

Giant sequoia seeds are only about as big as a pinhead, enclosed in a small, egg-shaped cone. Trees will not produce large amounts of seeds until they are several hundred years old. Reproducing giant sequoia trees will deposit millions of seeds each year; however, because of harsh growing conditions, there is a one in a billion chance that the seedling will grow into a mature tree.

Giant sequoias, like all other species, are subject to the effects of climate change.

It is estimated that 92% of the larger giant sequoia trees are protected by public agencies, namely the National Parks and National Forests. Yet despite this federal protection, parks can no longer guarantee the safety of the trees when faced with the consequences of climate change.

Giant sequoias only live on the western slope of the Sierra Nevada mountains in California. This restricted range puts them in danger as climate change threatens our planet. Climate change may cause the area to be too hot or too dry for the trees, putting the species at risk.

Giant Sequoia 7 Logo.jpg
Giant Sequoias looking down at the parking lot in King’s Canyon National Park

Cool facts about giant sequoias:

  • It is estimated that there are only about 20,000 giant sequoias alive that have diameters greater than 10 feet.
  • The roots of mature giant sequoias stretch out over 100 feet in every direction.
  • Giant sequoia bark is thick and contains little sap to help protect it from fires.
  • Giant sequoias are on the U.S. National Park emblem. This is because 3 of the 4 first National Parks created protected giant sequoias.

Resources to learn more:

Backyard Feeder Delights: The House Finch

Cover photo: © Michael Janke, 2016, some rights reserved.

From its pet shop introduction to the east coast to its ties to the study of disease spread, the cheerful house finch has a great story under its bright exterior.

Cover photo: © Michael Janke, 2016, Flickr Photo Album, some rights reserved.

Places to See House Finches

Pearson-Arastradero Circle.png

Pearson-Arastradero Preserve

Male house finches are reddish in color, while females are brown.

House finches are small songbirds – typically 5 to 6 inches in length. The males and females are sexually dichromatic, meaning that they differ in color. Male house finches have red heads, breasts, and rumps (the region just above the beginning of the tail). Males can have some variation in coloration, depending on their diet. Their wings and the rest of their body is brown. Females birds are brown and streaked.

House finches, like many other finches, have notches at the ends of their tails. They have small, cone-shaped bills and thin legs.

Male and Female House Finch

Above: Male and Female House Finch – © JanetandPhil, 2015, Flickr Photo Album, some rights reserved.

House finches are native to the western U.S., but have expanded out east.

House finches are native to the western part of the United States. In the 1940’s, a group of house finches were introduced to the eastern part of the United States. Since then, they have become a common sight all across North America. In some parts out east, populations of house finches will migrate short distances during the winter.

House finches can often be found in urban areas alongside humans.

While their native habitat was probably patchy areas near streams and grasslands, house finches have adapted well to living alongside humans in urban areas. House finches are commonly seem in vegetated neighborhoods and are frequent visitors to backyard bird feeders.

Male house finch coloration is the result of their diet.

House finches will eat seeds, buds, berries, and some small insects, such as aphids. At my home bird feeder, black oil sunflower seed is a favorite among visiting house finches.

Did you know male house finch diet is directly correlated with their coloration? Carotenoid pigment deposits in feathers are responsible for the males’ coloration. Differences in the concentrations and types of pigments for different males are what result in the variation of color.

House finches have a beautiful, flowing song.

House finches have a sweet, flowing song that’s commonly heard from treetops in neighborhoods. For examples of what they sound like, check out this page from the Cornell Lab of Ornithology.

House finches build cup nests and raise their young together.

Male and female house finches form pairs which sometimes last the entire year. To woo females, males will perform displays in which they sing and flutter upwards, then glide back down.

House finches nest above the ground, using locations that vary from vegetation to man-made structures. The females will do most of the building, constructing a cup nest made of fine twigs and grass. The clutch size, or number of eggs laid in a single nest, averages 4 – 5 eggs. Their eggs are pale blue in color.

After approximately 2 weeks of the female’s incubation, the eggs will hatch. The male and female take turns feeding the young until they leave the nest after about 2 weeks.

A pet shop heist resulted in the introduction of the house finch to the east coast.

In the 1940’s, pet shop owners were illegally breeding and housing house finches in New York City. To avoid prosecution, the shop owners released their birds. Thus began the introduction of the house finch to the eastern part of the United States. Since, house finches have established themselves all across the east. In some areas, populations of house finches have evolved to undergo short migrations south during the winter.

House finch studies give us insights on the spread of disease and the virulence of viruses.

In 1994, reports began showing up of a new sight at backyard bird feeders. The charismatic house finch, a beloved songbird, began showing up at some feeders with swollen, red eyes. Upon closer inspection, it was found that the ailment was caused by a poultry virus (Mycoplasma gallisepticum) that made a species-jump over to house finches.

This epidemic had a silver lining – the newly-arrived pathogen offered a natural study system by which to research disease spread. Headed by André Dhondt of the Cornell Lab of Ornithology, a citizen science-based program was created to monitor the spread of the house finch disease. The team was able to successfully track the spread of the house finch disease from the east coast all the way across the United States using mailed surveys. These data, along with other existing data on the abundance of birds before the introduction of the disease, made this study on wildlife disease novel.

The work didn’t stop there, either. After successfully monitoring the disease spread, the team turned to bigger questions about disease spread and pathogen virulence, or the severity of pathogen harmfulness. The work that began with mailed surveys led to groundbreaking research on diseases – work that is applicable to the human disease outbreaks that dominate headlines today.

For more detailed information on house finch conjunctivitis and the history of these studies, check out this article.

Resources to learn more:

Bay Area ‘Penguins’: Common Murres

Cover photo: © Mick Thompson, 2016, some rights reserved.

Did you know that common murre eggs each have a distinct speckled pattern? This is thought to help parents recognize them in the midst of crowded breeding colonies. Learn this and more in our post about this fascinating seabird!

Cover photo: © Mick Thompson, 2016, Flickr Photo Album, some rights reserved.


Places to See Common Murres

Common murres look a bit like penguins.

During the breeding season (summer), common murres are mostly white in front with black on the head and rest of the body. When they are not breeding, their heads have white on the neck and cheek.

Common murres live on the west and east coasts of North America.

Out west, common murres live along the coast from California up north to Alaska. Out east, their population is mostly around the coast of Canada.

Common murres are seabirds, meaning that they spend the majority of their lives out at sea.

Common murres are seabirds, meaning that they spend almost all of their lives out at sea in search of food. They will only return to land for brief period of time in the summer to lay eggs and raise their young. The young return to the ocean when they are old enough to enter the water.

Common murres eat a variety of sea life.

Their menu includes fish, crustaceans, squid, and marine worms. They catch their meals by diving under the ocean surface, sometimes reaching depths of 150 feet.

Common murres nest on rocky cliffs and islands.

Common murres nest in colonies, meaning that multiple birds of the same species will build nests close to one another in a given area. Common murres have the most densely-packed colonies of any species for its size, and breeding birds will sometimes have other individuals touching it on all sides.

Image result for common murre egg
Common murre egg; Source: Wikimedia Commons

Common murres don’t build “proper” nests; rather, they lay their egg directly on bare rock. This species lays a single egg, which has an intricate, speckled pattern and is very pointy on one end. Once the egg hatches, both parents will spend time feeding the young. At about 30 days of age, the young murre is able to enter the water. The parents spend several more weeks caring for the young bird at sea.

Common murres are very susceptible to population damage from oil spills.

By nature of being seabirds, oil spills drastically affect common murres. In the Bay Area, the 1986 Apex Houston spill and the 1998 Command spill killed thousands of birds and eliminated the population of common murres on Egg Rock at Devil’s Slide (Pacifica, Ca). Restoration of the birds at Egg Rock commenced in 1996, and the site is still being monitored today.

Common murres are one of many species affected by intense El Niño events.

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 that seabirds depend on.

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 thus puts strain on the seabird populations that rely on fish.

Cool facts about common murres:

  • Scientists speculate that the reason their eggs are so pointy is to avoid them rolling off cliff edges, since the eggs are not contained in nests.
  • The intricate speckled patterns on common murre eggs are thought to act as a “fingerprint” so that eggs can be individually recognized by parents.

Resources to learn more:

In Need of Protection: Western Snowy Plovers

Cover photo: © Pacific Southwest Region USFWS, 2009, some rights reserved.

Learn about a small species of threatened shorebird that can be found on the beaches along California’s coast.

Cover photo: © Pacific Southwest Region USFWS, 2009, Flickr Photo Album, some rights reserved.

Places to See Western Snowy Plovers

Wilder Ranch Circle

Wilder Ranch State Park

Western snowy plovers are disappearing in California due to disturbance and habitat loss.

The listing of the western snowy plover as federally Threatened in 1993 has led to very important conservation initiatives. Western snowy plovers are easily disturbed while breeding, so human activity and introduced predators (such as cats and foxes) disrupt their breeding seasons. This, along with the loss of healthy beach habitats, has resulted in the decline in western snowy plover populations. While it is estimated that their populations once numbered in the thousands, approximately 2,000 individuals are estimated to remain on our coasts today.

Today, several initiatives on California’s beaches are actively working to restore their populations. Groups of citizen scientists and biologists actively monitor snowy plover populations.

The restriction of dogs on beaches is another important initiative. Dogs disturb snowy plovers on nests, causing them to expend energy to flee. Even when on leashes, dogs have the capacity to do harm by disturbing the plovers. Because of this, actions are being taken at state beaches to enforce no-dog policies, and areas are being roped off from human activity so as to not disturb the breeding plovers.

Western snowy plovers are white and beige – perfect for blending in with sand on beaches.

Western snowy plovers are small shorebirds, reaching lengths of about 6 inches. They have thin, black bills and dark gray to black legs.

The bird’s upperparts, the area between the base of the bird’s neck to just above the tail, are pale gray to beige. They have white foreheads and a white stripe along the eyebrow line. The bird’s underparts, the area under the bird’s head to beneath its tail, are white. During the breeding season, adult birds will have dark patches on their shoulders.

Western snowy plovers live along the Pacific coast.

Western snowy plovers are found along the Pacific coast from Washington all the way down to Baja California. The birds that live along the coast generally stay there year round; however, some populations that live inland will migrate short distances to the coast for the winter.

Western snowy plovers prefer sandy beaches – a habitat also loved by humans.

Snowy plovers are prefer sandy beaches above the high tide line – an area that’s also commonly used by humans. They also can be found in salt flats. Snowy plovers prefer areas with little or low vegetation so that they are able to survey the area for predators.

Western snowy plovers like to snack on small invertebrates.

Western snowy plovers will eat small invertebrates such as sand fleas. They will often forage by running forward a few steps, stopping and picking up something that’s edible, then running forward again in search of more food.

Western snowy plovers have a variety of calls, often sounding like trilling or a whistle.

For the western snowy plover’s sounds, check out this page from the Cornell Lab of Ornithology.

Male western snowy plovers are in charge of taking care of young.

Snowy plovers breed from early March to the end of September. Their “nests” are not the typical nests that people are used to seeing. Rather, they are made in shallow depressions of sand. Their clutch size, or number of eggs that they lay in a single nest, is 3 on average.

Western snowy plovers are polyandrous, meaning that a female will breed with more than one male at a time. The males and females will share the task of incubating the eggs before they hatch; however, soon after hatching has occurred, some females will ditch the males and leave the responsibility of taking care of the chicks to him.

Snowy plover chicks are precocial, meaning that they are able to move around and forage very quickly after hatching. When looking after the young, adults will not feed them. Instead, they guide them to suitable feeding areas. Adults will look after the young until they fledge, or when their feathers and wing muscles are fully developed for flight. This takes about one month for snowy plovers.

Western snowy plovers act like they’re injured to protect their young.

When a predator is approaching a nest, adult snowy plovers will do a broken wing display, meaning that the adult will pretend to have a broken wing and move in a direction away from the nest. This is intended to lure the predator away from the nest,  to decrease the chance that the predator will find the nest and eat it.

Resources to learn more: