Category Archives: Water and Shore

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)

These Tadpoles Migrate Every Day

Screenshot of western toad tadpoles from Tadpoles: The Big Little Migration

2 April 2021

Three weeks ago frogs were singing and laying eggs in the vernal ponds of southwestern Pennsylvania. Many of the eggs have hatched by now. What do the tadpoles do next? This video from a remote lake on Vancouver Island, BC, Canada provides a hint.

Maxwel Hohn spent four years filming a tiny migration we never see. Every morning western toad tadpoles (Anaxyrus boreas) swim from their nighttime shelters to feeding areas in the lake, then back again to hide at night. The result is his award-winning 8+ minute video: Tadpoles: The Big Little Migration.

Our eastern American toads (Anaxyrus americanus) are closely related to western toads so I wonder if they do this, too.

Meanwhile, if the video wasn’t amazing enough for you, here are two more amazing things about tadpoles and toads:

  • Don’t worry that our tadpoles won’t survive the freezing temperatures this morning in eastern North America. Even if the ponds freeze, tadpoles are able to overwinter under ice. See photos at What’s Under the Ice? Wow! Winter Tadpoles from Oakland Twp, Michigan.
  • Do you know where North America’s toads came from? South America. And they didn’t walk! “Based on DNA sequence comparisons, Anaxyrus americanus and other North American species of Anaxyrus are thought to be descended from an invasion of toads from South America prior to the formation of the Isthmus of Panama land bridge, presumably by means of rafting. — from the Wikipedia description of the American toad.

Male Ducks Use Their Heads

Male common goldeneye (photo by Steve Gosser)

28 March 2021

In early spring male ducks use their heads to put on a show for the ladies. What most impresses their females? For many it’s a toss of the head.

During courtship common goldeneyes (Bucephala clangula) seem to have rubber necks. Click here to see their vigorous head tossing.

Among hooded mergansers (Lophodytes cucullatus) the head tossing is enhanced by their white hoods? Click here to see.

Male hooded mergansers, 2013 (photo by Steve Gosser)

(photos by Steve Gosser)

Osprey Back Yet?

Young osprey (photo by Dana Nesiti)

26 March 2021

There’s a Rule Of Thumb that says: Pittsburgh area osprey return from winter migration around St. Patrick’s Day.

This year the earliest eBird reports for southwestern Pennsylvania show osprey in Beaver and Butler Counties on 20 March 2021 and arriving this week along the Ohio River and at many lakes.

I haven’t seen an one yet so my goal this weekend will be to find an osprey, maybe at the Duquesne nest site.

My goal after that is to see an osprey do this …

(photo by Dana Nesiti)

Evolve Quickly!

Snail kite with island apple snail, Harns Marsh FL, 2017 (photo from Wikimedia Commons)

Native from Florida to Argentina, the snail kite (Rostrhamus sociabilis) is a gregarious bird of prey that eats only one thing: freshwater snails in the genus Pomacea. Its beak is specially shaped to do so.

Snail kite, Florida 2019 (photo from Wikimedia Commons)

The Snail Kite’s slender, deeply hooked, sharp-tipped upper mandible permits it to cut the columellar muscle of Pomacea snails and remove soft tissues from the shells. The arc of the upper mandible approximates the inner spiral of the snail’s shell.

— paraphrased from Birds of the World, Snail kite account

In the old days before humans took over Florida’s landscape, snail kites ranged over half the state, but we drained and diverted more than 50% of Florida’s wetlands, the snail kite population crashed and was listed as Endangered in 1967. Twenty years ago, from 2000-2007, their population dipped so low that scientists feared they would go extinct in the U.S. Then a curious thing happened. Their food supply changed and the kites changed so they could eat it.

Before this century the snail kite’s main food was the native Florida apple snail (Pomacea paludosa) but an invasive species, the island apple snail (Pomacea maculata), arrived in 2000 and began to spread in Florida’s lakes and water management areas.

Island apple snails eating rushes (photo from Wikimedia Commons)

The island apple snail is two to five times larger than the Florida apple snail as seen below. (The white-and-gray bars are each 5 cm.)

Size comparison of Florida apple snail (P. paludosa) to Island apple snail (P. maculata). Each scale bar is 5 cm (images from Wikimedia Commons)

When the island apple snail first arrived in Florida the snail kite population dropped but less than a decade later the population began increasing. Did the birds initially have a tool problem? Were their beaks too short to get at the snail inside the larger shell? A recent study from the University of Florida indicates this was probably the case. Since 2007…

Researchers found that the birds with bigger bills were surviving, and their offspring were inheriting the bigger bills. …

“We found that beak size had a large amount of genetic variance and that more variance happened post-invasion of the island apple snail. This indicates that genetic variations may spur rapid evolution under environmental change,” Fletcher said.

— paraphrased from UF study: Bird evolves virtually overnight to keep up with invasive prey

We think of evolution as a very slow process but for the snail kite it happened quite fast. Those with longer bills survived. Nowadays they easily eat island apple snails.

Male snail kite with island apple snail, Florida, 2016 (photo from Wikimedia Commons)

When it’s a matter of life and death, evolve quickly!

Read more at the University of Florida study: Bird evolves virtually overnight to keep up with invasive prey.

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

Goose Barnacles, Barnacle Geese

Goose barnacles, Lepas anatifera (photo from Wikimedia Commons)

20 February 2021

Goose barnacles often attach themselves to old wood and float from tropical seas to northern shores including the shores of Britain. The barnacles pictured here and in the video below are Lepas anatifera. Their bodies are supported by a long, flexible stalk (a peduncle) that resembles a goose neck. 

Goose barnacles and barnacle geese have similar names because people linked them to explain where the geese came from.

Every fall barnacle geese (Branta leucopsis) migrate to Britain and the east coast of the North Sea where they spend the winter. Those in Britain arrive from their breeding grounds in Greenland.

Barnacle geese (photo from Wikimedia Commons)

In the Middle Ages people didn’t know that birds migrate so they worked to explain the sudden appearance of full grown geese that they never saw nesting. Their explanation was that goose barnacles floated to shore, took root, and produced a tree that produced barnacle geese. This notion persisted for hundreds of years, from at least the 12th to 16th centuries.

Barnacle Geese. Facsimile of an Engraving on Wood, from the “Cosmographie Universelle” of Munster, folio, Basle, 1552

Nowadays that story sounds silly but we shouldn’t be too smug. We still create stories to explain things we don’t understand and spread them quickly on the Internet. In the future our fantastical stories will sound silly, too. I can think of a few about the coronavirus.

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

In a Sinkhole In a Lake

Tall “blip” on purple microbial mat in Middle Island Sinkhole, Lake Huron, June 2019 (Credit: Phil Hartmeyer, NOAA Thunder Bay National Marine Sanctuary)

11 February 2021

When I found this photo I had to find out more.

Though it looks something from outer space this unearthly pink blip is rising from a microbial mat inside the Middle Island Sinkhole (45.192515,-83.327195) in Lake Huron, about 12 miles from Alpena, Michigan.

Approximate location of the Middle Island Sinkhole (map from Wikimedia Commons, annotated)

Great Lakes sinkholes were found by accident in 2001 while looking for shipwrecks and have been studied for only 20 years.

Some, including the Middle Island Sinkhole, have vents that add water to the lake. This water is warmer than the nearby lake, has lower oxygen, 10 times the chloride, 100 times the sulfide, and a higher concentration of bacteria. The water looks very green.

This is the “perfect habitat for microorganisms known as cyanobacteria that form the somewhat eerie purple, white and green carpets on the lake floor.” Underneath the mats, methane and hydrogen sulfide bubble to the surface. The mat expands upward like wax in a lava lamp.

See what it’s like to scuba dive in the sinkhole at Diving with Ric: An underwater view of the Lake Huron Middle Island Sinkhole.

p.s. Fish live in some parts of the sinkhole. The photo below shows a burbot resting on a rock. If you don’t see the fish, click on the photo for a hint.

Burbot resting on rocks covered in purple and white microbial mats, Middle Island Sinkhole (Credit: Phil Hartmeyer, NOAA Thunder Bay National Marine Sanctuary)

(map from Wikimedia Commons, photos from NOAA Great Lakes Environmental Research Lab on Flickr)

Seeds Travel By Sea

Monkey-ladder vine (highlighted in red) and its heart-shaped seeds (photos from Wikimedia Commons)

5 February 2021

Many plants that grow near water disperse their seeds by riding the water wherever it goes. Fabulous among this group are tropical plants whose drift seeds cross the ocean.

The monkey-ladder vine or sea bean (Entada gigas), above, produces hard-covered heart-shaped seeds that contain an air pocket to keep them buoyant. Seeds from the Caribbean and Central America wash into the ocean and float on the Gulf Stream. Some make landfall 15 months later on the shores of Scotland.

Map of the Gulf Stream from NOAA Scijinks

This selection of drift seeds was found at the Outer Hebrides.

Drift seeds collected in Western Isles, Outer Hebrides, Scotland (photo from Wikimedia Commons)

They can also be found at Orkney as seen in this video from BBC Winterwatch.

The drift seeds traveled more than 4,000 miles to reach Orkney’s beaches and so did a lot of other things.

p.s. Click here to see a map of Scotland showing the Outer Hebrides and the Orkney Islands.

(photos from Wikimedia Commons, tweet embedded from BBC Winterwatch)

Why Do Rare Gulls Visit in February?

Lesser black-blacked gull in the UK (photo from Wikimedia Commons)

1 February 2021

If you want to see a rare gull that breeds in Europe or the arctic, February is the best time in Pittsburgh.

Gulls need open water for food and shelter so when ice forms they have to leave. Arctic breeders move to openings in the sea ice (polynyas) or fly south along the coasts or to the Great Lakes. When it’s very cold the Great Lakes freeze by February and the gulls move further south. That’s when they find Pittsburgh.

Though our city is 300 miles from the ocean a few gulls stay here year round. Several dozen herring gulls (Larus argentatus) breed on our rivers and a few non-breeding ring-billed gulls (Larus delawarensis) spend the summer. In winter they are joined by hundreds more.

Last week a single lesser black-backed gull (Larus fuscus) appeared at the gull roost where the Allegheny meets the Ohio. This species breeds on the coast of Europe and Iceland — and possibly now in Greenland and maritime Canada — but Pittsburgh is west of its normal range.

How did this bird get here? Here’s a wild guess: Perhaps he flew from the Atlantic to the St. Lawrence Seaway, Lake Ontario and Lake Erie and stopped when he got to Cleveland.

According to the Great Lakes Total Ice Coverage Map from 30 Jan 2021, the Toledo end of Lake Erie is fully iced up and it’s pretty thick now at Cleveland. If he was staying near Cleveland he would have to leave.

Great Lakes Surface Environmental Analysis for 30 Jan 2021 from NOAA

Will more rare gulls arrive this month? Check the Great Lakes ice conditions at NOAA for a hint of what’s to come.

(photo from Wikimedia Commons; click on the caption to see the original. map from NOAA’s Great Lakes Environmental Research Lab)

p.s. UPDATE 20 Feb 2021: Lake Erie was almost completely ice covered on 19 February 2021. See map below

Great Lakes Surface Environmental Analysis for 19 Feb 2021 from NOAA

Scenes Of The Week

  • Red leaves at Duck Hollow, 29 Nov 2020 (photo by Kate St. John)

5 December 2020

Here’s a visual portrait of the past week, from a warm day at Duck Hollow on 29 November, to snow on 1 December, and yesterday’s awesome sky at Moraine State Park.

(photos by John English and Kate St. John)