Category Archives: Water and Shore

Disappearing In The Sand

Coquina clams, open shells, Corpus Christi (photo by Pinke via Creative Commons license)

31 August 2021

Coquina clams (Donax variabilis) are tiny saltwater molluscs found on sandy beaches from Virginia to Texas. Their variable colors are beautiful and at only 3/4 inch long they are just the right size for collecting. I usually find an empty half shell rather than two joined like butterfly wings (above).

Colors of coquina clams (photo by Florida Fish & Wildlife via Flickr Creative Commons license)

Since I only pay attention to empty shells I never thought about where they live and how they get there until I saw this video. Watch two coquina clams disappear in the sand.

(photos from Pinke via Flickr and Florida Fish & Wildlife on Flickr)

Oystercatchers Grow Up

American oystercatcher with chick (photo from Wikimedia Commons)

16 July 2021

Though American oystercatchers (Haematopus palliatus) breed on barrier beaches and shelly islands on the Atlantic and Gulf coasts, few of us get to see it. The birds want peace and quiet far from humans when they raise a family.

@GetToKnowNature brings us this video of oystercatchers growing up, thanks to her long lens.

(photo from Wikimedia Commons, video from @GetToKnowNature)

Going Dry

Lake Mead bathtub ring, Feb 2017 (photo by Karen on Flickr Creative Commons license)

15 July 2021

This month a curious discovery in 2014 that predicted low water in the Colorado River and Lake Mead has come to alarming fruition. Lake Mead is going dry.

Lake Mead and Hoover Dam aerial view, May 2013 (photo from Wikimedia Commons)

The 20 year drought in the U.S. West is now severe, shown on the U.S. Drought Monitor map below.

Drought Monitor as of 8 July 2021 (image from U.S. Drought monitor,

Consequently the Colorado River is running very low and Lake Mead reached a crisis point last month. The Guardian reports:

In June [2021], the level of Lake Mead plunged below 1,075ft, a point that will trigger, for the first time, federally mandated cuts in water allocations next year. …

Should second tier cuts occur, Arizona will lose nearly a fifth of the water it gets from the Colorado River. Nevada’s first-round cut of 21,000 acre-ft (an acre-ft is an acre of water, one foot deep) is smaller, but its share is already diminutive due to an archaic allotment drawn up a century ago when the state was sparsely populated.

The Guardian: Severe drought threatens hoover dam reservoir and water for us west

The crisis is due to lack of precipitation but we learned in 2014 that loss of rain and snow is dwarfed by the depletion of groundwater.

Using nine years of NASA’s GRACE satellite data from the Colorado River Basin, UC Irvine and NASA scientists made an alarming discovery.  From December 2004 to November 2013 the watershed lost 53 million acre-feet of water, an amount almost twice the size of Lake Mead.  More than 75% of that loss was from groundwater.  No one knows how much water is underground but it’s going fast.

Outside My Window: Even Less Water Than We Thought

It’s a little spooky to see such a recent discovery come to pass so soon. Learn about the discovery in this vintage blog: Even Less Water Than We Thought.

Read about the current situation at: Severe Drought Threatens Hoover Dam Reservoir — and Water for U.S. West.

(photos from Wikimedia Commons, drought map from US Drought Monitor; click on the captions to see the originals)

How Shallow Is Lake Erie?

Sunset over Lake Erie at Presque Isle State Park (photo from Wikimedia Commons)

14 July 2021

In summer, folks in western Pennsylvania and northern Ohio flock to Lake Erie‘s shore to beat the heat. The water provides a respite but in July the western end is hotter than anywhere else in the Great Lakes. That’s because Lake Erie is shallow and shallow water is quick to take on the temperature of the surrounding air. So how shallow is Lake Erie?

Lake Erie is the fourth in line of the five Great Lakes and happens to be fourth largest by surface area — 9,940 square miles.

map of the Great Lakes (illustration from Wikimedia Commons)

But as you can see in this bathymetric map it is also the shallowest (blue is deep, red is shallow). Lake Erie’s average depth is only 62 feet with the deepest spot just 210 feet near Long Point, Ontario.

Great Lakes bathymetry map from Wikimedia Commons

It’s easier to see how shallow it is in this diagram from Michigan Sea Grant. Even Lake Ontario, the smallest by surface area, is 3.8 times deeper! (Lakes Michigan and Huron are superimposed on each other because they have the same pool level, 577 feet above sea level. Click here to see the complete diagram.)

Great Lakes System Profile (cropped diagram from Michigan Sea Grant via Flickr Creative Commons license)

Since the shallowest water is first to heat and first to freeze, the surface temperatures roughly match the lake depths. As of yesterday, 13 July 2021, the water at the western end of Lake Erie was close to 80 degrees F.

Great Lakes Surface Environmental Analysis, 12 July 2021 (map from Great Lakes Environmental Research Lab)

Fortunately the temperature has not yet spawned harmful algae blooms (HAB). If you’re going to the western end of Lake Erie this month, check the Lake Erie HAB forecast here before you go.

The lake is warm because it is so shallow. See the current temperature map here.

(photo and first two maps from Wikimedia Commons, Great Lakes system profile from Michigan Sea Grant, Great Lakes Suface Temperature from NOAA; click on the captions to see the originals)

Mallards in Eclipse

Male mallard in eclipse plumage, Colorado, July 2016 (photo from Wikimedia Commons)

7 July 2021

In the middle of summer the male ducks disappear — or so it seems. The males are still present but they look like females because they’ve molted into eclipse plumage.

Let’s take a look at mallards to see how this works.

Mallards (Anas platyrhynchos) replace all their feathers once a year but males and females do it at different times. Females molt while nesting (February–May); males molt after the breeding season (June–August).

The molt begins with a complete loss of remiges (wing flight feathers) that takes only a few days, rendering the bird flightless for 3-4 weeks. Fortunately males simultaneously replace their brightly colored body feathers with dull ones so they can hide in dense marshes. Eclipse plumage keeps them out of danger.

Here’s the transformation.

Male mallard gradually changing into eclipse plumage (photo from Wikimedia Commons)

Notice that the male’s head becomes mottled green (below) and then dull brown (photo at top).

Male mallard, head color is changing during molt (photo from Wikimedia Commns)

Once the males have made this transition it’s a challenge to tell them apart from females but here’s a clue. Look at their bills. In the summer males have yellow or greenish-yellow bills while females have dull orange-ish bills.

Mallards bills: male in eclipse, female in summer (photos from Wikimedia Commons)

Eventually the male starts to molt back to his typical plumage. Partway there he looks like this.

Male mallard in eclipse in Illinois (photo from Wikimedia Commons)

And by November he’s back to his normal flashy self in time to court his springtime mate.

Male mallard in spring plumage including the curly tail (photo from Wikimedia Commons)

This summer when you see a mallard, look at the bill. Maybe he’s a male in eclipse.

(photos from Wikimedia Commons; click on the captions to see the originals)

Reprise of Grassland Birds

Dickcissel in Clarion County, June 2012 (photo by Robert Greene, Jr)

24 June 2021

In early summer Pittsburgh birders tire of searching among dense leaves so we travel to Clarion County’s recovered strip mines for grassland birds. Yesterday five of us drove 90 minutes to look for open country birds we’ve found there in the past.

Dickcissels (Spiza americana) are back again this year and easy to find singing on the wires at Concord Church Road. These rare nomads were a Life Bird for me in 2012. Read this vintage article, Dickcissels, for the reason why they to come to western Pennsylvania.

At Piney Tract (actually a grassland) we saw Henslow’s sparrows (Centronyx henslowii) …

Henslow’s sparrow, Clarion County, Summer 2011 (photo by Steve Gosser)

and heard them …

And we saw a grasshopper sparrow (Ammodramus savannarum) singing …

Grasshopper sparrow, June 2017 (photo by Steve Gosser)

… but I could not hear him because I’ve lost the upper frequencies. Can you hear the really loud trill of this grasshopper sparrow?

We also looked for upland sandpipers (Bartramia longicauda) but, alas, they were not there. Seven years ago I saw four of these Magical birds at Mt. Airy.

Interested in exploring the Clarion County’s grasslands? Check out two locations plus photos in this vintage article: In The Scrubby Fields.

(photos by Robert Greene, Jr and Steve Gosser)

Can’t Fly Right Now

Canada geese during flightless period in July (photo from Wikimedia Commons)

23 June 2021

Feathers wear out so birds molt to replace them. Most species molt their flight feathers one pair at a time, losing a matching feather on each side, so they can continue to fly. Not so with swans, geese and whistling ducks. They replace all their feathers shortly after the breeding season in a single annual synchronous molt. During the molt they cannot fly.

Though it seems crazy to lose the ability to fly these large heavy birds are safe on water and unsafe in flight if missing a few feathers. It works for them to lose these flight feathers all at once.

Canada goose flight feathers highlighted on the wing (photo from Wikimedia Commons)

Geese rarely display their stubby wings but you can tell when they’re molting by looking at their tails. Most of the year their flight feathers cover their rumps (left). When molting (right) you can see a white rump patch.

Not-molting vs. molting appearance in Canada geese (photos from Wikimedia Commons)

Right now in Pittsburgh Canada geese are in their flightless period that lasts six weeks from mid-June to August. You’ll see them flock in or near large bodies of water, feeding on land and walking to the water to swim to safety. You might even notice they are absent from favorite feeding places, such as Flagstaff Hill, which don’t have bodies of water nearby. Such sites are unsafe when they cannot fly.

Have you seen any Canada geese flying lately? No. Because they can’t.

p.s. Goose mitigation plans do not harass geese during their flightless period. The best mitigation is done before they nest. For example, see the Allegheny Commons goose mitigation plan here.

(photos from Wikimedia Commons; click on the captions to see the originals)

Solitary Sandpipers Nest In Trees

Solitary sandpiper, Cap Tourmente NWA, Quebec (photo from Wikimedia Commons)

11 May 2021

Whenever we see this sandpiper species he’s up to his ankles(*) in water and is poking with his long bill to eat insects, crustaceans, mollusks and amphibians.

Solitary sandpipers (Tringa solitaria) are distinguished from other shorebirds by a white eye ring, white spots on dark back, and the fact that they’re usually alone. We see them on migration as they travel between their wintering grounds in Central and South America and breeding grounds in the muskeg bogs and boreal forests of Canada and Alaska.

Everywhere they go they land on the ground and walk in water. I have never seen one in a tree and yet …

Solitary sandpiper range map from Wikimedia Commons

When solitary sandpipers reach their breeding grounds they nest in trees.

Solitary Sandpipers use old nests of songbirds in trees, especially those of American Robins, Rusty Blackbirds, Canada Jays, and Cedar Waxwings, which are usually near the trunks of small trees a few yards above the ground, but may be higher. [that’s 9 ft or higher]

Males identify old songbird nests that have potential, and females apparently make the final selection. Females modify the nest by removing old lining and often relining with fresh materials.

All About Birds, Solitary SANDPIPER ACCOUNT

The nest looks like this specimen at the Burke Museum. Notice that the eggs are pointed like common murre eggs.

Solitary sandpiper nest with eggs (photo from the Burke Museum via Flickr Creative Commons license)

It’s hard to imagine a shorebird standing in a tree so click here for a drawing of a solitary sandpiper at its nest from Birds of the World.

Incredible as it seems, this shorebird nests in a tree.

p.s. I know of only two other tree-nesting sandpipers: green sandpiper (a Eurasian relative of the solitary sandpiper) and Nordmann’s greenshank in Siberia.

(*) The backward-facing knees on birds are actually their ankles.

(photos and map from Wikimedia Commons, Burke Museum Flickr, click on the captions to see the originals)

Why Do They Wag Their Tails?

Two tail bobbers: Spotted sandpiper, Louisiana waterthrush (photos from Wikimedia Commons)

14 April 2021

One of the joys of early spring is finding the first Louisiana waterthrush (Parkesia motacilla) of the year as it forages along a stream and sings its loud distinctive song. The bird is so loud that we hear him first then look for movement along the water’s edge. He stands out because he constantly bobs his tail. In fact he bobs the entire back end of his body!

Just half a minute of this video illustrates what I mean.

A few weeks later the spotted sandpiper (Actitis macularius) arrives to walk the water’s edge bobbing the entire back end of his body, too.

Same habitat, same movement. Is there some advantage in drawing attention to one’s back end? Why do these birds wag their tails? I found a partial answer at All About Birds:

… waterthrushes don’t actually wag the tail, they dip (or teeter) the entire rear of the body by moving their ankle joints. This motion is very much like the bobbing of Solitary and Spotted Sandpipers, which share their wetland habitats. It’s been suggested that this habit might either help them avoid scaring off their prey or possibly startle their prey into motion.

All About Birds, overview of Louisiana Waterthrush

There’s plenty of time to watch them teeter in the weeks ahead. My first Louisiana waterthrush of 2021 was at Cedar Creek Park in Westmoreland County on 30 March. I expect the first spotted sandpiper next week.

Bonus! Here’s a closeup of a Louisiana waterthrush singing:

(photos from Wikimedia Commons; click on the caption to see the originals)

p.s. Others birds pump their tails including eastern phoebes, palm warblers, hermit thrushes, wagtails and pipits. It is not quite the same motion.

Easter Island has Christmas Birds

Moai on Easter Island (photo from Wikimedia Commons)

4 April 2021, Easter Day

When Europeans explored the Pacific they sometimes named islands for the day they found them. Thus Easter Island (Rapa Nui) was named by Dutch explorer Jacob Roggeveen who encountered it on Easter Day 5 April 1722 and Christmas Island (Kiritimati) was given its English name by Captain James Cook on Christmas Eve 1777.

Easter Island is best known for its nearly 1,000 stone statues, moai, created by the Rapa Nui people. Kiritimati (pronounced “Ki-rismas” in the local language) is so remote that it was used for nuclear bomb tests 60+ years ago. Today the entire coral atoll is a wildlife sanctuary.

Range map from Birds of the World via Wikimedia Commons

Christmas shearwaters (Puffinus nativitatis) are pelagic birds that nest on remote Pacific islands (map) and were named for their largest breeding colony at Kiritimati, Christmas Island.

Christmas shearwaters roosting on Tern Island, French Frigate Shoals, Hawaii (photo from Wikimedia Commons)
Christmas shearwater on nest with its single egg, Midway Atoll (photo from Wikimedia Commons)

They also nest on Easter Island … so Easter Island has Christmas birds.

p.s. Happy Easter 2021.

(photos and map from Wikimedia Commons, sound from Xeno Canto. Click on the captions to see the originasl)