Park Sentries: Canada Geese

Cover photo: © Don DeBold, 2017, some rights reserved.

Learn about the Canada goose, a common visitor to California’s parks and fields.

Cover photo: © Don DeBold, 2017, Flickr Photo Album, some rights reserved.

The Canada goose has the most widely-distributed range of any goose in North America.

They are found year-round in parts of the northern United States. Birds that breed closer to the Arctic will migrate south to the United States for the winter. In some parts of California, there are areas where geese are found year-round. For more information on their range, check out this map by the Cornell Lab of Ornithology.

Their migratory v-formations headed north in the spring and south in the fall are widely recognized as symbols of the changing seasons.

Canada geese tend to forage in moist fields and manicured lawns.

There, Canada geese graze on grasses and grains from cultivated plants. Manicured lawns are particularly attractive to Canada geese, as the short vegetation allows them an unobstructed view of the landscape to look out for potential predators.

Canada geese are also known to eat aquatic plants.

Canada geese build their nests near water.

Females select the location, and do most of the work to construct a cup-shaped nest. They lay 2 – 8 eggs, which hatch after around a month of incubation. The hatchlings are covered in yellow down. As precocial hatchlings, they are able to walk, swim, and dive as soon as they leave the nest. The young will stay with their parents for a year, traveling as a family group.

Breeding pairs are monogamous, and have low rates of “divorce” – or splitting up. They form pairs usually during their second year of life.

When birdwatching, it pays to look closely at flocks of Canada geese.

I’ve been delighted during some birding walks to find another species mixed in with flocks of Canada geese. While at Shoreline Regional Park, I was lucky enough to find some greater white-fronted geese foraging with the Canada goose flock I was watching. Greater white-fronted geese are a rarer species in the Bay Area, so it was a treat to be able to watch them.

Canada & Greater White-fronted Geese Logo
Greater white-fronted geese foraging alongside Canada geese at Shoreline Regional Park in Mountain View, Ca.

Cool facts about Canada Geese:

  • Contrary to popular belief, the term “Canadian Goose” is incorrect. The common name of this species is “Canada Goose”.
  • Canada goose populations in urban areas have been increasing since the 1950’s.

Resources to learn more:

Backyard Buzzers: Anna’s Hummingbirds

Cover photo: © jacksnipe1990, 2017, some rights reserved.

Sound produced by tail feathers? Nests made of spiderwebs? Learn about these facts and more in our post about the Bay Area’s winter hummingbird.

Cover photo: © jacksnipe1990, 2017, Flickr Photo Album, some rights reserved.

Anna’s hummingbirds are permanent residents in the Bay Area.

While some species of hummingbird migrate during the winter, the Anna’s hummingbird stays in the Bay Area year-round.

Their range has greatly expanded beyond its initial restriction to California and Baja California. Today, Anna’s hummingbirds can be found in parts of the southwestern United States, as well as up in British Columbia, Canada. Their expansion is thought to be related to their adaptability to feeding on exotic flowers and their use of artificial food sources (hummingbird feeders).

Anna’s hummingbirds are the most common hummingbirds on the west coast.

They can be found in a variety of habitats, ranging from urban gardens to open oak woodlands. Individuals can be located easily by listening for their buzzy song, which is often sung from atop a perch.

Anna’s hummingbirds eat nectar and insects.

Anna’s hummingbirds feed of nectar from native and non-native plant species, as well as artificial nectar provided at hummingbird feeders. It’s estimated that 90% of a hummingbird’s diet is composed of nectar, whereas the remaining 10% is composed of small insects.

Anna’s hummingbirds are a bright and feisty visitor at my own hummingbird feeders. They can be quite territorial, as exemplified by some individuals perching near the feeders and chasing away any unwelcome visitors that wander over in search of food.

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Source: © Mick Thompson, 2017, Flickr Photo Album, some rights reserved.

Anna’s hummingbird males generate a non-vocal “squeak” during their breeding displays.

During the breeding season, male Anna’s hummingbirds display for females. During their display, males sing energetically, then rise up to 130 feet into the air. They follow this flight with a sudden and quick dive. As they dive, a “squeak”-like sound is produced by air moving through modified outer tail feathers.

Females are responsible for all nesting responsibilities.

Anna’s hummingbirds have a breeding system in which females are solely responsible for parental care. Female Anna’s hummingbirds construct nests of soft plant fiber and spiderwebs that are 1.5 inches in diameter and 1 inch high. She lays 2 eggs, which take 16 days to hatch. Once hatched, the female will feed and care for the young until they are old enough to fly out of the nest at 23 days old.

Cool facts about Anna’s hummingbirds:

  • In the Bay Area, an Anna’s hummingbird nest once delayed construction at the Richmond-San Rafael bridge. The nest, protected under the Migratory Bird Treaty Act, was discovered in a grove of trees designated to be cut down for the expansion. The crew halted removing the trees until after the nest and birds were gone.
  • Anna’s hummingbirds are capable of torpor. When temperatures drop outside at night, Anna’s hummingbirds will also drop their own body temperatures. They simultaneously slow their heart rates and breathing to enter a hibernation-like state. Once temperatures rise again, they resume normal bodily functions.
  • All hummingbirds are only found in North and South America.

Resources to learn more:

Ocean Gliders: California Brown Pelicans

Cover Photo: © Frank Schulenburg, 2016, some rights reserved.

Brown pelicans have made a dramatic return from their critically low numbers in the 1970’s due to the effects of DDT. However, the fight for the brown pelican is far from over: today, they face threats from food scarcity as Pacific sardine and anchovy numbers have shown declines.

Cover Photo: © Frank Schulenburg, 2016, Flickr Photo Album, some rights reserved.

Places to See California Brown Pelicans

natural bridges circle

Natural Bridges State Beach

California brown pelicans faced critically low numbers in the 1970’s from the effects of DDT and endrin.

From the 1950’s to 1970’s, the brown pelican almost disappeared from North America due to the effects of pesticides, namely endrin and DDT. DDT weakened the strength of breeding birds’ eggshells, resulting in failed breeding attempts as parents crushed eggs while trying to incubate.

The plummeting populations resulted in the species being federally listed as endangered. The ban of DDT in 1972, as well as the decrease in use of endrin, allowed pelican numbers to recuperate. By 2009, the species had recovered enough for its endangered listing to be lifted.

On the west coast, pelican populations face declines from lack of food availability.

Today, all brown pelicans still face threats from oil spills, entanglement in fishing gear, and disruption during their breeding season.

On the west coast in particular, however, pelican populations face starvation due to a decrease in the availability of Pacific sardines and anchovies. Overfishing and unusually warm waters have caused declines in the two fish populations, which has in turn negatively impacted brown pelican populations. In 2010, emaciated pelicans were reported at California wildlife centers. Younger pelican individuals were even recorded going after murre colonies in Oregon, grabbing chicks and shaking them until they regurgitated fish for the pelicans to eat.

In response to low fish numbers, the commercial fishing of sardines was banned from April 2015 through June 2016. To help monitor the populations of brown pelicans along the west coast, citizen scientists and biologists conduct surveys to assess pelican numbers from Mexico up north to Washington.

Moss Landing Brown Pelicans
Source: © Don DeBold, 2015, Flickr Photo Album, some rights reserved.

Juvenile California brown pelicans appear brown overall, whereas adults sport more rich coloration.

Non-breeding adult pelicans have yellowish faces and white necks. The rest of their bodies are brownish gray.

During the breeding season, the necks of adult brown pelicans turn reddish-brown in color. On the west coast, breeding adults also develop a red throat. Birds in breeding plumage can be seen from December through August.

Juvenile brown pelicans are brown above and whitish below, with grayish bills.

California brown pelicans can be found resting along California’s coast.

Brown pelicans can be found foraging in shallow waters. When they’re not searching for food or breeding, they can be found resting in areas near the coast.

While in flight, birds will typically form lines. Their flight is extremely graceful, as they glide and flap in unison.

California brown pelicans feed by diving in the water.

They feed primarily on fish, diving head-first into the water from 20 – 40 feet in the air to capture their prey. Before swallowing the captured fish, pelicans empty their pouches of water. The California brown pelican and the Peruvian pelican are the only two pelican species that plunge dives for food.

Gulls, particularly Heermann’s gulls, are known to steal fish from the pouches of brown pelicans that have just returned from a dive.

California brown pelicans nest colonially on the ground.

Brown pelicans breed on the Channel Islands in Southern California from March to early August.

To breed, brown pelicans form colonies, meaning that they nest in large groups with members of the same species. Their nests are usually constructed of sticks.

They lay 3 eggs on average, which hatch after 4 weeks of incubation. Once the eggs hatch, the young are cared for by both parents.

Cool facts about California brown pelicans:

  • The largest roosting site for brown pelicans in the Bay Area is in Alameda on Breakwater Island. Breakwater Island is an L-shaped island in Alameda, built from rocks to help reduce wave action in the area.
  • Brown pelican pouches can hold up to 2.6 gallons of water.
  • Brown pelicans can live to be up to 30 years old.
  • Brown pelicans are incredibly large, with wingspans of 6.5 to 7.5 feet.
  • Brown pelicans weight 8 to 10 pounds.

Resources to learn more:

Mysterious Declines: The American Kestrel

Cover photo: © Gregory “Slobirdr” Smith, 2007, some rights reserved.

Learn about North America’s smallest falcon and its mysterious decline across the United States.

Cover photo: © Gregory “Slobirdr” Smith, 2007, Flickr Photo Album, some rights reserved.

Places to See American Kestrels

Pearson-Arastradero Circle

Pearson-Arastradero Preserve

American kestrels are experiencing declines throughout the United States, including coastal California.

Data from the Peregrine Fund’s American Kestrel Partnership suggest that the coastal California population has been experiencing declines since the 1960’s.

Scientists do not know the “one true cause” of kestrel declines in the United States; rather, they believe that multiple causes could be working together to depress populations. Possible causes include habitat loss, the use of neonicotinoid insecticides, and local threats from the use of anticoagulant rat poisons.

Many local organizations are working to construct artificial kestrel nesting boxes to help the numbers in their area. For more information on how to construct a kestrel nesting box, check out this page by the Cornell Lab of Ornithology’s NestWatch.

American kestrels are North America’s smallest falcon.

They are about the size of a mourning dove, measuring in at 8.7 – 12.2 inches in length. Male American kestrels have beautiful slate-blue wings and rusty backs/tails. Females, on the other hand, are more subtly-beautiful – they have rusty wings and backs. Both males and females have black “slashes” on their faces.

You can often recognize American kestrels by looking for a bobbing head or tail. This charming behavior makes these birds distinctive on telephone wires, even at a distance.

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Male American kestrel; Source: © Matthew Buynoski, 2018, all rights reserved.

American kestrels eat large insects, small reptiles and amphibians, and even the occasional small bird.

American kestrels are raptors, meaning that they subdue and kill their prey using their feet. They hunt by swooping down on small prey and grabbing it in their talons.

Kestrels will sometimes cache, or store, extra food to keep it for later consumption or hide it from other animals.

American kestrels are secondary cavity-nesters, meaning that they build their nests in cavities excavated by other animals.

Once established at their nest site, female kestrels lay 4 – 6 eggs that are incubated by both parents. After about a month, the eggs hatch. The young and the female are fed by the male for a couple of weeks, after which the female leaves and begins to forage as well. The young begin to fly about a month after hatching.

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American kestrel at Pearson-Arastradero Preserve; Source: © Matthew Buynoski, 2018, all rights reserved.

Cool facts about American kestrels:

  • American kestrels are also known as “sparrow hawks” or “mousers”.
  • Only the northern populations of American kestrels migrate south during the winter. Central and southern populations are permanent residents.
  • American kestrels have a very distinct and excitable call, making these birds easy to locate by sound. To hear the American kestrel call, check out this page.

Resources to learn more:

American Kestrel 2
Male American kestrel in flight; Source: © Matthew Buynoski, 2018, all rights reserved.

Colorful Corvid: The Yellow-billed Magpie

Cover photo: © Marcel Holyoak, 2011, some rights reserved.

Did you know that our site logo is a yellow-billed magpie? Learn more about why we chose this stunning bird.

Cover photo: © Marcel Holyoak, 2011, Flickr Photo Album, some rights reserved.

Yellow-billed magpies are the inspiration for Bay Area Naturalist’s logo as bright, personable birds that are only found along California’s coasts and Central Valley. While their restricted range makes them very special to see, it also makes them susceptible to the threats that climate change poses to our planet’s life. They inhabit open oak woodlands – a specialized habitat that could mean that this species will not be able to adapt well to changes brought about by our changing climate.

For more information on why we chose the yellow-billed magpie as our logo, check out our Site Logo page.

Yellow-billed magpies are found in California’s Central Valley and along the coast.

This species is endemic to California, meaning that they are only found in our state. Its range is quite restricted, covering an area just 500 miles long and 150 miles wide. They are found in open oak woodland habitats, usually near bodies of water.

Although they’re not found in the heart of the Bay Area, they can be seen in parts of the East and South Bay. Coyote Valley Open Space Preserve and Joseph D. Grant County Park are excellent places to see yellow-billed magpies in the Bay Area.

Yellow-billed magpies have a diverse diet.

They eat insects, fruits, seeds, and will scavenge for food. They have also been known to be kleptoparasitic, or steal food from other animals.

Yellow-billed magpies construct large, dome-shaped nests.

Often found on oak limbs, their nests are lined with mud on the inside. They nest in colonies of 3 to 30 pairs that maintain loose association with one another. They lay 5-8 eggs on average.

The female incubates the eggs, sustained by food brought from the male. After 18 days of incubation, the young hatch. Both of the parents will participate in feeding and caring for the offspring.

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Yellow-billed magpie nest; Source: DavisWiki

Yellow-billed magpies were hit hard by West Nile Virus.

In 2004 when West Nile Virus established itself in California, yellow-billed magpie populations suffered. It is estimated that the virus killed half of their population in just two years. Habitat loss and pesticide-use also threaten this species.

Cool facts about yellow-billed magpies:

  • The oldest yellow-billed magpie ever found was just shy of 10 years old.

Resources to learn more:

Treetops to the Ocean: Marbled Murrelets

Cover photo: © Aaron Maizlish, 2017, some rights reserved.

Marbled murrelets are full of surprises – defying all expectations of a seabird, they nest high up in redwood trees. Learn about their nest discovery in 1974 and their close ties with coast redwoods.

Cover photo: © Aaron Maizlish, 2017, Flickr Photo Album, some rights reserved.

Places to See Marbled Murrelets

Marbled murrelets are seabirds.

By nature of being seabirds, murrelets spend the majority of their lives out at sea in search of food. They eat mostly fish and crustaceans.

Marbled murrelets are very unique amongst seabirds in that they nest high up in redwood trees.

Most other seabirds, including their close cousins puffins and murres, nest on rocky cliffs along the shore. The marbled murrelet defies all expectations of a seabird by nesting high up in redwood trees. They will sometimes travel 30 miles inland to nest.

Their solitary nests up in old-growth trees makes them very difficult to find – a tactic that’s thought to help discourage predation. Parents will also only fly to the nest to switch who’s incubating or to feed young very early in the morning or late at night to avoid detection by predators.

Marbled murrelets are different colors in the breeding and non-breeding season to camouflage with their different habitats.

Marbled murrelets are small, robin-sized birds. They are black on top and white on bottom during the non-breeding season (any time when they’re not attracting mates or nesting).

Marbled murrelets adopt mottled brown plumage during the breeding season – a unique transition that’s not found among their close relatives. This brownish color is thought to help them camouflage with the redwood trees that they nest in.

Marbled murrelets live along the northwest coast of the United States.

Their range extends from southeastern Alaska to northern California.

The marbled murrelet is listed by the state of California as endangered.

In Oregon and Washington, the species is listed as threatened. Factors such as habitat loss, predation by other birds (namely Steller’s jays), and low food availability have affected their population.

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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.

In many California state and national parks, you’ll notice a campaign urging visitors to keep their space “crumb clean”. This movement is to discourage the number of Steller’s jays and other scavenging birds that are attracted to food that people leave behind.

Why be worried about attracting Steller’s jays, when it’s a charismatic and attractive bird? Well, in addition to eating human leftovers, Steller’s jays will also eat the eggs and young of other birds. One such species is the marbled murrelet, whose numbers are negatively affected by Steller’s jay predation.

Cool facts about marbled murrelets:

  • The marbled murrelet’s nest was discovered in 1974 by accident, when a tree climber in Santa Cruz stumbled upon its nest.
  • Marbled murrelets are the most recent species to have their nest discovered in North America.
  • Marbled murrelets are also known as “fog larks”, since their keer-keer call was heard early in the morning high up in redwood forests. It wasn’t until their nest was discovered in the 1970’s that people put together who was vocalizing.

Resources to learn more: