Birds by the bay

Arriving at the peak of low tide the other evening gave us some great looks at a diversity of shorebirds foraging along the shore of Eloise Roemer bird sanctuary on Alameda Island in San Francisco Bay.

Lots of Dunlin, Willets, Curlews, Great Egrets, Pelicans, Cormorants, Avocets, — wow, what a shorebird mecca this tidal area is!
A couple of Long-billed Curlews resting on one leg…
A trio of Willets…
Double-crested Cormorants, White Pelicans, and kayakers enjoy the quiet water of this sheltered bay.
Low Cormorant on the totem pole gets the small rock, I guess.
Stilts and Yellowlegs hunting in the shallows.
Greater (i think) Yellowlegs have beautifully edged wing and back feathers when you can see them up close.
Black-necked Stilts have such delicate toes at the end of those long, pink legs.
and on the grassy side of the beach, a beautiful little Western Bluebird hunting for insects in the waning light.

Down by the bay

A quick trip to the marshy shoreline of Alameda Island in San Francisco Bay yesterday evening gave us an impressive view of hundreds of busy shorebirds feasting on mud-dwelling critters.

And the skyline of San Francisco across the bay from the island…
And a lovely sunset with little shorebirds still foraging for last crumbs from the mud.

Amazing sand beaches of Dauphin Island

We took a car ferry to Dauphin Island which sits at the mouth of Mobile Bay, and then drove west to Pelican Point beach for a (hot) walk in the late morning sun. The beaches along the gulf coast of this part of Alabama are composed of finely ground, minuscule particles of quartz that originated in the Appalachian mountains, were ground down by erosion and river action before being transported to the gulf, where minerals were further reduced in size by wave action over tens of thousands of years. The result is an eye-blinding, fine, white sand that actually squeaks as you walk over it.

It’s hard to decide which is whiter — the sand or the puffy cumulus clouds. Little islands of sea oats grasses and herbaceous perennials help stabilize the dunes. But this is harsh habitat for these plants that have few mineral nutrients and precious little fresh water resources and must deal with a lot of salt water spray.
Farther away from the ocean, more perennial grasses can establish mats of vegetation.
In salt water pools behind the beach, one might find a few shorebirds foraging for food. We were surprised to find a tiny Least Sandpiper poking around in the vegetation at the water’s edge.
Even farther away from the ocean, the vegetation is much thicker and more diverse with all kinds of perennial grasses and forbs growing on the sandy matrix. I surprised a Great Blue Heron and Black-bellied Plover as I came around the corner of this small pond.
A flock of Red-winged Blackbirds (all females and immature males) were feasting on the sea oats.
The Dauphin Island fishing pier ends far short of the ocean now, due to sand buildup between Pelican Point (which used to be an island) and Dauphin Island.
Looking toward the interior of Dauphin Island, you can see the successive ridges of white sand dunes deposited over time, and colonization first by grasses, then various species of shrubs, and finally dense stands of pines and oaks, the species best adapted to growing in dry, sandy conditions.
In the interior of the island, you can find huge, old live oak trees, covered with mosses and epiphytes, and surrounded by saw palmetto and a variety of flowering plants. These are impressive giants, both in their size and in their survival in a climate of intense heat, periodic drought, and occasional hurricane landfall.

Alabama’s gulf shores are an ecological wonder!

at the beach

It seems like when we’re not in the mountains, we’re at the beach. That’s the wonderful thing about California — the variety of places to explore. This time it was the beautiful sands of Pajaro Dunes, where the gently sloping shore allows you to walk far out into the waves and not even get your knees wet.

The grandkids enjoyed the ocean and the bird life, and especially skipping rope with a giant piece of brown kelp.

Running with the Ring-billed Gulls
This is good practice for jumping creeks in the Sierras later this summer.
Brown Pelicans catching an updraft from the wave action.
Digging for clams — it was fun finding them, but this was strictly catch and release.
As soon as the clam was placed back on the sand, its muscular foot began digging it back under the surface again.
In just a few moments, the clam had almost completely required itself (note sand spray from its “foot” at the bottom of the image).
Grassy vegetation on the dunes holds some of the sand in place. These dunes were a lot taller than they appear, and the sand was quite deep. A single stand of brown kelp provided many minutes of entertainment…

Ghost ship

One of the landmarks of the Santa Cruz coastal area in California is the wreck of the concrete ship at Seacliff beach. When we visited the beach in the early morning fog, the ship appeared ghostly and mysterious, except for the hundreds of birds that have made the deteriorating framework their roosting area.

The ship is broken in half and sinking into the bay here, but there are ample structures above water for roosting Brown Pelicans, Double-crested Cormorants, Ring-billed Gulls, and lots of Pigeons.
Hundreds of birds perch on exposed rebar from the deteriorating concrete.
Cormorants and Pelicans fly to and from the ship on hunting trips for fish, but they almost disappear in the fog.
It’s a ghostly sight as it disappears into the thick fog layer on the beach on this particular morning.

The cement ship, SS Palo Alto, (weird construction material for a ship!) was commissioned to be built as an oil tanker in WW1 in 1919, but the war ended before it made its maiden voyage. It was then towed to this area along the Monterey Bay coastline in 1929 and served as an amusement park/entertainment center, with a casino, dance hall, arcades, etc., until its owners went broke during the Depression in the 1930s.

Both the ship and the pier it once attached to are rotting away, but their remains make for some interesting photography.
On this foggy morning, the sky and the sea blend into one another. Few people are out on the beach to “enjoy” the sights.

You “otter” see this!

We didn’t expect to see so many sea otters on our boat tour of the Elkhorn Slough in Monterey Bay. Several were in sight at any one time, almost every one with a youngster riding on top as the adult paddled along on its back.

Sea Otters propel themselves with their hind feet while floating on their backs. This mama has a small youngster curled up on her chest, its head tucked under its body.

Sea Otters were once very abundant in the coastal marshes and estuaries of western North America, but extensive hunting up until the early 1900s culled their numbers to just a couple thousand animals. Conservation efforts have increased their numbers somewhat, but they are only found in part of their original range. Sea Otters are an important part of the coastal ecosystem because they prey on the sea urchins that ravage the kelp beds and keep the herbivore numbers in check.

The Sea Otter diet is largely made up of shelled invertebrates like mussels, abalone, snails, and sea urchins. Otters are unusual in carrying and using a tool, a good-sized rock that they can tuck into a fold of skin, to pound on shells to break them apart. They can also open some shells with their incisors.

Sea Otters bring their prey to the surface, and consume it while floating on their backs. Naturally, some of the food drops onto their fur as they eat, so they continuously roll over while eating to dislodge food fragments. In addition, they meticulously groom their fur to keep it clean and fluffy (i.e., with lots of air pockets).

The density of otter fur is one of their most important adaptations to marine life. It is extremely thick, with about 1 million hairs per square inch! Multiple layers of fur shed water and trap air, enhancing their ability to float on the surface and keep a dry layer of fur next to their skin. Young otters have an extra layer of inner fur to trap air which gives them extra buoyancy. While grooming them, their mother may actually blow air into their fur, making them so buoyant, they float like corks.
Long vibrissae on their noses help them detect prey under the water. Sea Otters apparently also have an excellent sense of smell, and their eyesight is as good above water as below the surface. When they dive, otters can close their nostrils and ears to water entry.

Otters breed at all times of the year, and pregnancy usually lasts about 4 months, but females can delay the implantation of the single embryo until conditions are best for the pup’s development. Pups stay with the mother 6-8 months, before venturing out on their own, when they are almost full adult size.

This little otter won’t be with its mom much longer…

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the three amigos

We had our own personal boat tour of the Elkhorn Slough, a 7-mile long tidal estuary on Monterey Bay that was the first estuarine sanctuary in the U.S. It began with a 60-acre purchase by The Nature Conservancy in 1971, and has grown to over 800 acres today. The entire 1.5 square mile marine reserve provides critical habitat for a variety of mammals (discussed in the next post), more than 300 species of birds, and a host of invertebrates and plant species on which the birds and mammals depend.

By some strange coincidence, a number of the bird species we saw on our boat tour had arranged themselves in groups of three — thus, I labeled the trios “the three amigos”. This is the time of year when bachelor groups of males break up and mated pairs are more often seen together, so seeing groups of three was somewhat odd.

White Pelicans are still hanging out in large flocks at the slough, but three loners were standing together. Male and female White Pelicans look alike, so we don’t know whether this was a group of just bachelor males or not.
These Eared Grebes swam together, dove together, and posed together, as they hunted for small crustaceans and fish in the rich estuary waters. The sexes look alike, so one or more could be female. Eared Grebes nest in dense colonies, so it’s not unexpected to find them in small groups together.
Pigeon Guillemots (relatives of Puffins) are handsome black and white birds with red legs and feet. The sexes look alike and are similar size, although in California, the female Guillemot has a slightly larger bill. Although they may be enjoying the largess of the estuary, they will soon set up nesting territories on steep cliffs all along the west coast of North America.
A trio of Brandt’s Cormorants had settled on some rotting pier posts to establish their nests. They seem to be sitting on eggs already in the estuary; they would have to be tolerant (or good friends) to nest this closely together. Brandt’s are the largest Cormorant in North America and are easily distinguished by their vivid, cobalt blue throat and eyes.
“I’m so pretty…”

The Rock

it juts right out of the ocean, a lone, huge boulder of a rock, standing 580 feet high. Morro Rock is one of the “nine sisters of San Luis Obispo County”, a series of volcanic plugs that rose into softer rock about 20 million years ago. The Rock is part of the state park and is closed to hikers and climbers so that Peregrine Falcons, Western Gulls, and Brandt’s Cormorants (among many other bird species) have a protected place to breed and raise their chicks.

Almost 500 feet above us, a group of Brandt’s Cormorants have established nest sites on a shelf of the rock face (arrow— you may be able to see them if you click on the photo to enlarge it). Western Gulls have staked out their favorite nest sites on the various rock ledges as well. The minute dots of birds against the rock face gives you a sense of just how massive this rock is.
Along the shore you can find plenty of shorebirds, as well as some great views.
Western Gulls are plentiful, and they quickly hone in on what the humans around them are eating for lunch on the beach.
Left-over French fries…yes, they love them.
Gulls don’t bother the napping Harbor Seals, but this one looks surprised by the fly-by.
A pair of California Thrashers were setting up housekeeping along one of the hiking trails in the park. Like other members of the Mimid family (mockingbirds and catbirds), thrashers are notable songsters. Thrashers construct complex songs that contain phrases from many other songbirds, strung together in long series with few repeats, often lasting 3-5 minutes. One study found almost 3,000 phrases in a single California Thrasher song.
They may be plain-looking but friendly little California Towhees are easy to find in California chaparral vegetation and are sort of an indicator species of the California scrublands. They scratch around the base of plants for hidden seeds, the same way Fox Sparrows do in the Midwest.
Red -shouldered Hawks have a strange distribution in North America. They are mostly an eastern bird of the forests, but a limited western population occurs west of the Sierra Nevada mountains from Northern California to northern Baja California. We were fortunate to see one of the birds fly into the tree where the other hawk perched, just as we were leaving the state park.

Behold, the beaks!

We have been stopping along the California coast at various sites from San Diego to the Santa Cruz area to check out the shorebirds there. What a wealth of diversity of birds, and what a diversity of adaptations they exhibit, especially in their beaks.

Of course the beak is the primary tool for extracting food in shorebirds, so you would expect to find specialized structures to do that. For example:

Beaks come in different lengths, different curvatures, different thicknesses — all designed to find and extract prey from different locations in the shore environment. (Illustration of beaks in Western Australian birds by Peter Dann)

Even closely related species (e.g., in the same genus) exhibit particular beak structures that allow them to specialize on certain food resources. Few species exhibit the extreme specialization of the Curlews, whose very long and decurved bill is designed to extract crabs and other soft-bodied invertebrates embedded deep in the wet sand or mud.

Long-billed Curlews are the largest of the Sandpiper group of shorebirds, and almost seems oversized for the bird’s small head. Its sensitive tip can locate prey buried far below the surface.
The closely related Whimbrel is half the size of the Long-billed Curlew, but it, too, uses its long, decurved bill to seek out prey buried deep in sand and mud. Where both species are present together, they would be foraging at different depths and thus avoid competing directly with each other.
Willets are common on the ocean shoreline as well as inland, and seem to be more generalist feeders. They probe for crabs and other invertebrates in the sand and mud, but forage for insects, and even plant material away from the shore.
Another member of the same genus as Willets, the Greater Yellowlegs, is about the same size, but weighs half as much as a Willet. This bird is more of a specialist on aquatic invertebrates and fish, using its beak to stir up the water and dislodge its prey from the bottom.
Marbled Godwits use their long, slightly upturned bill to sift the wet sand for tiny invertebrates. Here, they are probing shallow surfaces out of the water, but they also stand belly deep in the water with their heads and necks fully immersed to hunt for prey.
Avocets use their sword-like, upturned bill to sieve the shallow water for small invertebrates. They sweep their bill side to side in the water, picking up minute crustaceans, worms, and even tiny fish.

This has been a subject of interest every time I visit the California shore, and there is more information about this (and a video) in a previous post: “sharing the resources”

Birding in Puerto Vallarta

Goodbye, San Diego, hello (two days later) to Puerta Vallarta, an upscale commercial and tourist port on Mexico’s scenic west coast.

Leaving the port of San Diego CA on the M/S Rotterdam
Lovely mountains ring part of the city and frame a beautiful sandy beach where we sat and watched Frigate birds dive for food thrown out by fishermen.
Magnificent Frigatebirds diving for scraps
Then a long walk to an estuary reserve near the pier, where we could have seen much more if we had taken a boat ride instead of walking around a mangrove forest.
Lots of iguanas were basking in the mangrove bushes
And Yellow-crowned Night Herons had staked out places in the mangroves to hunt for fish, crabs, etc.
What stealthy (and extremely slow) stalkers they are
Black, White, and Red mangroves grow in a dense tangle in this estuary (Estero el Salado), just 1/2 mile from the ship dock! Mangroves drop aerial roots to the substrate to strengthen their position and to advance the zone the mangroves occupy. These plants are vital as a buffer for storm surge during tropical deluges.