Some birds change their feathers for the breeding season. Others change the color of their skin.
In the non-breeding season, June to December, the bare skin on anhingas’ (Anhinga anhinga) faces is an unremarkable yellowish-brown that blends with their plumage and beaks.
But beginning in January their bodies transition to breeding plumage and their faces turn bright turquoise. Even the normally dull, brown-necked females have resplendent blue-green around their eyes.
Watch their fancy faces in this video from South Carolina.
Avian influenza, also called bird flu, is in the news lately because a highly contagious strain has made it to North America from Eurasia. Though not dangerous to humans, this year’s strain is easily caught by some bird species, most notably chickens. Here’s what it is and what we can do to protect birds.
What is this virus?As USDA explains, “Avian influenza is caused by an influenza type A virus which can infect poultry (such as chickens, turkeys, pheasants, quail, domestic ducks, geese, and guinea fowl) and wild birds (especially waterfowl).” Various strains are always in the wild but the low pathogenicity versions do not cause illness in wild birds or chickens. Every few years, however, a highly pathogenic (HPAI) strain surfaces that is extremely infectious, fatal to chickens, and rapidly spreads in domestic poultry.
This year’s HPAI strain has already devastated many poultry farms.
Which birds have died? USDA is tracking the virus and reports that millions of commercially raised chickens and turkeys have already died this year. As of 7 April 2022 the total death count was more than 24.2 million, the vast majority of which — more than 16 million — were Commercial Layer Chickens. That’s why the price of eggs has gone up. (See USDA commercial andbackyardflock statistics here.)
If you are a poultry farmer, have backyard chickens, or have captive birds in a zoo or rehab facility you’ll want to heed USDA’s advice to protect your birds. Accordingly the Pittsburgh Zoo, the National Aviary, and HARP’s wild bird rehab facility in Verona are taking precautions. (See this Post-Gazette article.)
Should we worry about wild birds? Not so much. Wild birds maintain their own social distancing whereas domestic poultry live in crowded conditions on factory farms.
In addition, avian flu is primarily caught by ducks, geese, swans, chickens, wild turkeys, pheasants and quail. Some raptors catch it, though in low numbers. Songbirds are at low risk.
As of 7 April 2022, USDA testing of dead wild birds has found 637 cases in the U.S. 88% were water-related birds, notably mallards and snow geese. 11% were raptors. The highest raptor death toll was among black vultures who roost communally. (See USDA wild bird statistics here.)
Notice the order of magnitude here: 24.2 million poultry deaths versus 637 wild bird deaths.
Interestingly, the species most susceptible to avian influenza are closely related and stand alone in the the phylogenomic supertree below (pale green branch at bottom right) while those least susceptible are least related to ducks and chickens.
And finally, here are two quotes from the New York Times:
Nearly all the nine billion chickens raised and slaughtered in the United States each year can trace their lineage to a handful of breeds that have been manipulated to favor fast growth and plump breasts. The birds are also exceptionally vulnerable to outbreaks of disease. “They all have the same immune system, or lack of an immune system, so once a virus gets inside a barn, it’s going to spread like wildfire,” said Dr. Hansen, the public health veterinarian.
Andrew deCoriolis, the executive director of Farm Forward says: “Instead of asking how factory farms can prevent infections that originate in the environment, which is how they frame it now, we should be asking how they can prevent infections that originate on factory farms,” he said. “If we keep raising more and more animals in these conditions, we should expect the exact outcome we’re getting because that’s how the system is set up.”
Les Leighton had his camera set up at Canada’s Vancouver harbor when a drama played out in front of him. A gull zipped by with both a bald eagle and peregrine falcon pursuing it in flight. What was it about that gull that attracted two predators at the same time?
Watch the chase and notice the difference between the eagle’s and peregrine’s hunting techniques. Why did both of them give up?
Intersex hen mallard, Duck Hollow, 20 March 2022 (photo by Michelle Kienholz)
22 March 2022
On Sunday at Duck Hollow we saw a female mallard with odd plumage. She was paired with a male mallard but she resembled a male in eclipse plumage. Was this duck a hybrid? Or was it something else?
Intersex hen mallard with her mate, Duck Hollow, 20 March 2022 (photo by Michelle Kienholz)
Michelle Kienholz was so intrigued that she took photos and sent them to the Duck ID group where she learned an amazing thing about female ducks. This odd mallard at Duck Hollow is an “intersex hen.” She is becoming male in a process called spontaneous sex reversal (SSR).
Female ducks are born with two ovaries but only one develops. The left ovary actively pumps out hormones to stifle the male genes, making the bird truly female. If a disease damages the only ovary and it stops producing hormones the female duck spontaneously turns into a male. Experiments have shown that the now-male duck is able to breed and fertilize eggs.
Because most ducks are sexually dimorphic a female with a dead ovary eventually looks male as well. The intersex hen at Duck Hollow is partway through her/his outward transformation, which is why she/he is in eclipse-like plumage.
Notice the clues in her/his feathers that indicate the transition:
tail feathers are black and curly white,
green feathers interspersed on head
breast is darkening (top photo)
color line between neck and breast is becoming white
Intersex hen: tail end is black with white feathers, green feathers on head (photo by Michelle Kienholz)Intersex hen, color line between neck and breast is becoming white (photo by Michele Kienholz)
For more information on bird sex chromosomes see Anatomy: W and Z. For photos of eclipse plumage see Mallards in Eclipse. And here is an article about spontaneous sex reversal in chickens, a problem for chicken farmers.
What looks like a glowing pincushion (above) or piece of plastic in the tweet below is an animal called a nudibranch. It’s not pronounced the way it’s spelled. The “ch” is a “k.” This is a “NEW-dih-brank.”
Nudibranchs are sea slugs whose name means “naked gills” though some of them have no gills at all. From a video at DeepMarineScenes I learned that nudibranchs are …
3000+ species of sea slugs similar to snails but without any shells inside or out,
Found from the poles to the tropics, most often in shallow tropical waters,
Carnivores that eat sponges, corals, anemones, etc.
Range in size from 1/4 inch to 1 foot long,
Use smell and feel to get around. Their eyes sense only light and dark.
Brightly colored from the toxic things they eat.
Toxic themselves. Their color warns off predators.
Their only real predators are other nudibranchs. Yow!
We think of mallards (Anas platyrhynchos) as dabbling ducks that eat plant material and bread tossed by humans(*) but these common ducks are actually omnivorous and opportunistic. Their diet depends on time of year.
On migration and in winter mallards are basically vegetarian, eating seeds, acorns, aquatic vegetation, cereal crops, and in urban areas human-provided bread and birdseed.
Fortunately small bird consumption is quite unusual and unnecessary. Males and non-laying females eat only 37% animal matter in the breeding season while laying females consume 71.9% animal matter to meet their energy needs.
I saw a pair of mallards mating at Panther Hollow Lake last weekend so I know the breeding season has begun in Pittsburgh. Laying females will be bulking up on snails, insects and worms.
Meanwhile most mallards are still on migration to their breeding grounds. They will change their diet soon.
The color combination helps them forage. While their black legs are probably ignored by their prey, the “yellow feet catch the eye of fish and other creatures, drawing them closer or stalling them so the egret can strike,” per Bird Watcher’s Digest.
Here are three of the snowy egret’s five foot-fishing techniques.
Foot stirring:
Foot probing: in slow motion.
Foot dragging: Dangling their feet in the water to make the fish rise up from the depths.
Much of the coastal U.S. floods during violent ocean storms but some places, like Miami, flood several times a year during high “spring” or “king” tides because of climate-driven sea level rise. This month a new report from NASA and NOAA recalculates how deep the water will be just 30 years from now. It doesn’t look good.
By 2050, the average rise will be 4 to 8 inches along the Pacific, 10 to 14 inches along the Atlantic, and 14 to 18 inches along the Gulf.
As Wired Magazine points out, these amounts are averages because water basin topography, water temperature (warmer water takes up more space), land subsidence, and glacial rebound make unique results for each location.
Comparing just two cities on different coasts neatly illustrates what a striking difference these factors can make. Galveston, Texas, where the land is slumping, could see almost 2 feet of rise by the year 2050. Meanwhile, Anchorage, Alaska, could see 8 inches of sea level drop, thanks to the fact that its land is actually rising following the departure of long-gone glaciers.
The report indicates that a 2-foot rise is already locked in for 2100 because of past greenhouse gas emissions. If we don’t stop emitting *now* we can expect an additional 1.5 to 5 feet for a total of 3.5 to 7 feet by the end of this century.
NOAA’s Sea Level Rise Viewer shows Galveston, Texas, below, in three scenarios: current sea level, +2 feet (expected by 2050) and +7 feet (in 2100 if nothing changes). In 30 years Bayou Vista, Tiki Island and Jamaica Beach will be gone. A 7-foot rise by 2100 wipes out most of the area.
Galveston, Texas at current sea level (map from NOAA Sea Level Rise Viewer)
Galveston, Texas with 2 foot sea level rise (map from NOAA Sea Level Rise Viewer)
Galveston, Texas with 7 foot sea level rise (map from NOAA Sea Level Rise Viewer)
No matter what happens the results will be unequal. Southern Alaska (blue dots) looks good under both scenarios. The Gulf and Atlantic coasts will be in various degrees of trouble.
The report is sobering because it’s unfolding so soon. If you’re 30 years old now, some Gulf Coast places will be gone by the time you’re 60.
(images from Wikimedia Commons, NOAA’s Sea Level Rise Viewer and NASA & NOAA’s 2022 Sea Level Rise Technical Report; click on the captions to see the originals)
A flock of gulls takes off as a towboat passes, Duck Hollow, 17 Feb 2022 (photo by Jim McCollum)
26 February 2022
Despite Pittsburgh’s overcast skies, winter can be beautiful along the Monongahela River. Jim McCollum often stops by Duck Hollow to capture its many moods.
Ring-billed gulls visit Pittsburgh in winter and on migration to their nesting grounds at the Great Lakes and Canada. In February adult ring-bills look sharp in breeding plumage.
Ring-billed gull on a log tossed up by the river, Duck Hollow, 18 Feb 2022 (photo by Jim McCollum)
This month Pittsburgh had more than 5 inches of rain with several big rain events: 1.02″ on 3 Feb, 1.60″ on 17 Feb, and 1.07″ on the night of 24-25 Feb. When the flood waters receded on 24 Feb they left behind an unusable gift on the remnant mud bank which had never had a picnic table. Soon the water rose again.
A “gift” from the river is deposited on the mud bank, Duck Hollow, 24 Feb 2022 (photo by Jim McCollum)
In addition to gulls Duck Hollow has visiting ducks in winter, including common mergansers (Mergus merganser).
Common mergansers at Duck Hollow, 31 Dec 2021 (photo by Jim McCollum)
And there are always mallards (Anas platyrhynchos) that give the place its name.
Male mallard lands on still water at Duck Hollow, 30 Dec 2021 (photo by Jim McCollum)
p.s. Duck Hollow is at the end of Old Browns Hill Road and across the river from Homestead, near the Homestead Gray’s Bridge (previously called the Homestead High Level Bridge). Click on this link to see it on the map.
Take a visual trip to Florida and watch at least 10 species of birds feeding in a marsh. Notice that some stab at underwater prey, others nibble below the surface, some pick at the shore and some (the pink ones!) swipe their bills side-to-side.
How many of them can you identify? Leave a comment with your answer.
(Note: The embedded video is limited it to the first two minutes. Click here to see the entire 13.5 minute video.)
