Curlews, Clams, and Calcium

Long-billed Curlew

Long-billed Curlew

The next time you visit the beach or a river sandbar, test your dexterity by using a pair of chopsticks to locate, capture, and extract some small clams from their subsurface burrows.

You may find that the experience will give you a new respect for what Long-billed Curlews commonly do with ease.

Razor clam headed to the gullet

Razor clam headed to the gullet

Of course the curlews do not have access to the grocery store, so if they want to eat they have to use their noggins and bills effectively.

As I watched these birds foraging in the shallow waters at low tide in the San Diego River channel of Southern California, several thoughts occurred to me.

On the way

On the way

First, how do the birds recognize a target site to probe?  They seem to totally ignore some areas and lightly touch or shallowly probe other areas before they really get down to business.

Could such things as taste and smell be involved in locating a clam?  What about vibrations in the sand as a clam tries to burrow deeper?

Last minute adjustments

Last minute adjustments

Second, how does a curlew catch and capture an actively burrowing clam without getting a beak full of sand?

As the curlews probe deeply, the birds appear to twist their heads and bills in a corkscrew fashion which may simply be following the path of the clam or it may provide some torque for their bills.

Another clam

Another clam

Third, how does a curlew generate enough force to grasp and hold onto a slippery clam shell?  Perhaps the curve of the bills comes into play here.

When bent against the grain, curved objects seem to be capable of generating force to return to their original shape when the stresses are released.  For common examples one can think of springs, archery bows, and some flatbed trailers used in the trucking industry.

Adjusting the grip

Adjusting the grip

Whatever the source of energy, the bill must grasp the clam shell firmly enough to hold it against the suction of the sand or mud as the bill is extracted.  Maybe this is why one sees few, if any, long-billed shorebirds with straight bills.

Fourth, if the clam had the capability to jet itself down through the sand in burrowing deeper, why does it not try to do the same as it is being extracted by a curlew?  Also, for the occasional clam that the curlew drops onto the riverbed before swallowing it, why does the clam not use its jets to spurt away?

Whoops!

Whoops!

Could it be that the clams are stunned by the suction forces generated when the curlews finally open their bills as they contact the subsurface clams?  Although the mechanics are probably different, both large-mouth bass and alligators can capture nearby prey items by suddenly opening their mouths and letting water currents suck the prey into their waiting jaws.

In the water!

In the water!

Fifth, are the clam shells that are swallowed used as a source of calcium for developing egg shells?  If so, is clam eating confined to female Long-billed Curlews or do males participate as well?

Could it be that calcium-supplying clam habitats are a critical part of a Long-billed Curlew’s life history, and that population dynamics for these birds can depend on the availability of these habitats.  Could it also be that past and current distribution patterns and ranges for this species can be partially explained by reviewing the distribution of these clamming areas?

Let's try this again

Let’s try this again

Paraphrasing Mark Twain, science is fascinating as one can generate so much speculation from so few facts.  While these questions currently have the status of being personal working hypotheses, I may eventually find evidence to accept or refute them.  When or if that happens, the following quote (attributed, I believe, to one of the Huxleys) may apply:   “Another beautiful hypothesis killed by the ugly facts.”

Until then, keep at it with the chopsticks.

You can view the video at https://youtu.be/Ckj55Yvy700

Ahhh!  There's nothing like a good clam!

Ahhh! There’s nothing like a good clam!

 

 

 

 

 

 

 

Leave a comment

Persistence Pays Off

Red-bellied Woodpecker

Red-bellied Woodpecker

After three to four minutes of pecking at a bark crevice on a dead pine tree, this Red-bellied Woodpecker extracted a small acorn.  As you watch the video    https://youtu.be/t9n1UdEKR4I     you can see the woodpecker alternately peering under the bark to check its progress and then hammering away some more.

How did an acorn come to be wedged under a piece of bark on a dead pine tree?  Did it fall and land there, or did something deliberately place it there?   What mammal or bird would try to hide an acorn like this?

Leave a comment

Snowy Egret Foraging at Famosa Slough, San Diego, California

Snowy Egret on the prowl

Snowy Egret on the prowl

Here are some items to note about the Snowy Egret behavior in the video       https://youtu.be/KPrW88Zg3Rg         at the Famosa Slough site, San Diego, California.

First, note the characteristic Snowy Egret shake-a-leg foraging technique used to flush potential prey from their hiding places.

Second, note the running, turning, wing-flashing technique to pursue active prey.  The egret may be using its wings to: 1) help maintain its balance; 2) keep its wing feathers out of the water; 3) shade the water surface to improve the bird’s underwater viewing of potential prey; and/or, 4) create shade to trick a fish into mistaking the shade for a hiding place.

Still looking for food

Still looking for food

Third, note the vigorous bill-shaking response used after the bird jabs into the water column and/or the mud bottom.

I haven’t seen enough instances of the bill-shaking behavior to know if it varies from bird to bird, or if the bird found the water and/or mud distasteful.  Possibly the salt content of the water is too high for the egret’s taste.  Maybe the mud bottom tastes of sulfur (e.g., ferrous sulfide and/or hydrogen sulfide) and that was distasteful to the bird.  Or, perhaps the egret is just trying to shake some mud from its bill.

Famosa Slough

Famosa Slough

 

Information for the visitor

Information for the visitor

As the habitat shows and as the sign indicates, the City of San Diego should be commended for preserving and enhancing a pocket of estuarine salt marsh that clearly is valuable to local wildlife populations and to the citizens of San Diego.

 

 

Leave a comment

Riding the Rails

If you ever wanted a model train for Christmas, then this working model railroad diorama set is for you.

Train dioramas are doodling carried to the ultimate three-dimensional level.

The video is available at        https://youtu.be/crJzKqmkNAM

Leave a comment

Fish in the Desert

Desert Pupfish and water ripples

Desert Pupfish and water ripples

It is my understanding from what I was told that the small fishes darting around in these shallow pools are indeed desert pupfish       https://youtu.be/mbFhoUzI0SM

Floating algae mats

Floating algae mats

I don’t know much about these fish and their habitat requirements, but apparently these conditions seem to suit their tastes.

Fan palm oasis habitat

Fan palm oasis habitat

So, if you happen to be an ichthyologist wandering around in the desert looking for water, you should consider visiting the Dos Palmas Preserve located just east of the north end of the Salton Sea, California.

Old timer

Old timer

If, however, you happen to be a botanist looking for plants or an ornithologist looking for birds, you would also enjoy visiting this site.

 

 

 

 

Leave a comment

Sailing and Para-sailing, San Diego, California

Sailing on the bay

Sailing on the bay

Both of these activities, sailing and para-sailing, seem to be delightful ways to practice interstate commerce and to enjoy the nation’s navigable waters.

Para-sailing on the bay

Para-sailing on the bay

If para-sailing had been available in his day, Leonardo da Vinci may not have had time to spare to paint the Mona Lisa.

See the video at

 

Leave a comment

Ballet of the Water Pancakes

Freshwater marsh

Freshwater marsh

As the video –      https://youtu.be/n134lSA18h8     - begins, note the layered character of the herbaceous plant canopy.  Some water lily leaves (Nelumbo lutea) float on the water surface while others are held erect one to three feet above the surface.  The water surface appears to be shaded between 100% and 200% by the outlines of these leaves.

Multi-layered herbaceous canopy

Multi-layered herbaceous canopy

The water repellent character of the leaf surfaces and the water properties of adhesion to a surface, cohesion between water molecules, and surface tension combine to create the flat pancakes of water.

Nelumbo lutea leaves

Nelumbo lutea leaves

The movements of these water pancakes induced by slight to moderate breezes create an excellent opportunity to study water menisci phenomena associated with the interaction of the water and leaf surface properties.

Water pancake on water lily leaf

Water pancake on water lily leaf

These water pancakes probably create their own set of environmental conditions associated with evaporation, light, and heating influences that may constitute unique habitats for tiny aquatic organisms.

An unusual aquatic habitat

An unusual aquatic habitat

As one result, these water pancakes may serve as satellites orbiting the primary aquatic ecosystem of the marsh below.

The dances of these water pancakes are thus interesting to contemplate, fun to watch, and demonstrate the art of science.

Leave a comment

An American Bald Eagle

Bald Eagle scans its world

Bald Eagle scans its world

Here is a personal and professional tip-of-my-hat to Rachel Carson, to other past, present, and future professionals in wildlife sciences and management, and to the individuals and organizations of conservation in America.

I enjoy and value each bald eagle sighting I make.

Bald Eagle with its eye on things

Bald Eagle with its eye on things

Thank you one and all.

The video can be found at    https://youtu.be/ZAdcDiEcGfs

Leave a comment

Whoop-it-up for Whooping Cranes

Look for the juvenile whooper with rusty plummage

Look for the juvenile whooper with rusty plummage

From a personal standpoint, watching Whooping Cranes conduct their activities amid the backdrop of hundreds to thousands of sandhill cranes milling about is akin to viewing an old masters original painting in a museum.

Whooping Cranes and Sandhill Cranes

Whooping Cranes and Sandhill Cranes

The controlled setting of a national wildlife refuge or a museum is necessary because society has invested much effort in both instances to protect, preserve, and maintain its treasures for past, present, and future generations.

Note the colored leg bands used for identification

Note the colored leg bands used for identification

The vivid blues of a Vermeer painting are equaled by the regal white, red, and blacks of the Whooping Crane.  The rusty “cinnamons” of young whoopers reflect the mud, sweat, and tears invested by their parents as they conduct their personal lives, which just happen to constitute the fragile threads of continued existence for a species.

Seeing is believing, and an experience of watching and studying Whooping Cranes in person has no substitute.

Let’s keep it going forever.

My Whooping Crane video is available at

https://youtu.be/llzBMyafoZ4

Leave a comment

Scarborough Loon – Dozing on a Rising Tide

Common Loon on the Scarborough River.

Common Loon on the Scarborough River.

This Common Loon was floating on the Scarborough River in the vicinity of the western end of the pedestrian causeway across the Scarborough Marsh near Portland, Maine.

The loon appeared to be relaxing and napping or dozing with its eyes alternately partially closed or fully closed, or briefly open to look around.  While the loon typically was facing downstream (i.e., to the right in the video clips), the incoming high tide created a current flowing upstream (right to left).

The loon was apparently paddling just enough to maintain a stationary position relative to the bank.  Occasionally the bird would stop paddling, drift upstream with the tide, and then resume another stationary position, or move gently downstream against the current.

Common Loon - napping or dozing

Common Loon – napping or dozing

Presumably this location provided a good opportunity for this behavior as I saw the bird doing this on two different dates (11/30/2016 and 12/3/2016).  Although I did not see any evidence of the loon trying to forage for fish on either visit (i.e., no diving and no swimming with its eyes underwater), it seems reasonable that this habitat would be suitable for fishing.

Perhaps the loon had fed earlier, and/or would feed later under different tide and river current conditions.

The video is available at    https://youtu.be/JYmMnHdo9IY

Leave a comment