Yellow Northern Cardinal?

There’s been quite a buzz the last few weeks in the bird world about this picture:

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Yellow Northern Cardinal (Image by Jeremy Black)

Nope, that’s not Photo-shopped. That is a real yellow Northern Cardinal.

The story of this cardinal began back in January, when it was spotted by birdwatcher Charlie Stephenson of Alabaster, Alabama. She was looking at her feeder when she noticed a yellow bird, but did not realized right away that it was a Northern Cardinal.

So she contacted ornithologist Geoffrey Hill of Auburn University and her friend, photographer Jeremy Black, to take pictures of this rarity. The cardinal stuck around Stephenson’s yard for a few weeks. At the end of February the photo of the cardinal went viral on Facebook.

So how exactly did this Northern Cardinal, which is normal red, become yellow?

Pigments are found in both plants and animals. In birds, pigments are found independent of feather structure. There are three pigment groups found in birds: carotenoids, porphyrines, and melanin.

Carotenoids are responsible for pigments found in birds that are yellow, red, and orange. Since carotenoids are produced by plants, birds with these pigments get them by ingesting plant material or something that ate the plant material. The quality of a bird’s diet plays a role in how brightly-colored feathers are. Birds with a poor diet will be paler in pigments than a bird with a richer diet. A theory from some scientist and birders is that diet as well as environmental factors may be affecting this cardinal’s color.

Ornithologist Geoffrey Hill believes that the yellow cardinal has xanthochroism. This is a genetic mutation where the carotenoid pigments being drawn in by the bird’s diet are yellow instead of red. Xanthochroism has been seen in other birds such as House Finches, Evening Grosbeaks, and other Northern Cardinals.

Whether the cardinal’s color is due to genetics, environmental factors, or diet, it really is quite beautiful. It’s certainly a very special and lovely sight to see.

Have you ever seen a bird that was a different color than it was supposed to be? Tell me about it in the comments. 

Mind. Blown.

I read a fact the other day that blew my mind.

I was reading an article on Audubon’s website called “Who Wins the Feeder War?” by Nell Durfee. In this article, Durfee explains about a new study in feeder hierarchy. The author then presents 5 “duels” you may observe at a feeder along with some facts about each bird. You can read the article at http://www.audubon.org/news/who-wins-feeder-war.

I am reading and enjoying this article and get to Mourning Dove vs. House Sparrow. I click on the Mourning Dove and read a really crazy fact. And I quote:

“Store large amounts of food in crop (record is 17,000-plus seeds in one dove)”

17,000-plus seeds?! Woah!! Mind blown.

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Mourning Dove at Amico Island (Image by BirdNation)

So of course I needed to investigate this amazing fact further. I stumbled upon a Washington Post article from January 2012 called “Mourning doves: Gluttons of the bird feeder” by Patterson Clark (you can read that article here).

In one day, a Mourning Dove can consumes as much as 20% of their own body weight. In order to do this, they need to store food in a crop. A crop is a specialized area that is found in some bird species. It is an enlargement of the lower esophagus that aids in food storage so that the bird can move safely. The food will stay in the crop until the bird is ready to either pass the food into its stomach or regurgitate it to its young. In some birds, cells in the crop lining will help produce a “crop milk” that is rich in lipid to feed to their young.

It’s fascinating that this record-setting Mourning Dove fit over 17,000 seeds in its crop! The avian body is amazing. Mourning Doves love seeds and will happy devour as much food as possible from your feeder. They prefer platform feeders, ones with a perch, or just simple flat ground.

Next time you check your feeder, keep a careful lookout for the gluttonous Mourning Dove. They might try to eat you out of house and home using their crops!;-)

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Mourning Dove at my feeder (Image by BirdNation)

 

Birds of a Feather

What do you imagine when you hear the word “feather”?

It’s likely that you imagine a tail or wing feather. But did you know there are 6 major types of feathers on a bird’s body? Each of the major types has specific form and function.

Let’s start by defining two important terms in regards to feather structure. A feather is either pennaceous or plumulaceous. Pennaceous feathers are what most people imagine to be a “typical” feather. Pennaceous feathers are flexible and consist of the following parts:

  • Vane-  the flat surface of a pennaceous feather
  • Barbs- hundreds of stiff filaments that attach to a rachis
  • Rachis- a relatively solid structure that extends down the middle of the feather
  • Ramis- a central shaft which has slender branches on either side
  • Barbules- the slender branches on either side of the ramis.
  • Barbicels- tiny hooklets that attach the barbules together and create the flatness of the vane
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Anatomy of a feather (Image via Birdtricks.com)

Plumulaceous feathers have barbs that are loose and fluffy. Their barbs have rami that are less stiff and the barbules are usually either reduced or thinner. As a result, plumulaceous feathers cannot hold anything except a delicate, rounded form. When you see a chick with down, you are seeing an example of plumulaceous feathers.

Feathers grow out of and remain attached to a feather follicle in the epidermis. If you’ve ever seen the bumps on a plucked chicken, then you have seen feather follicles.

Now that we’ve discussed the basics of feather structure, let’s examine the 6 major feather types.

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Major Feather Types (Image via Bird Academy/Cornell Lab of Ornithology)

1. Down Feathers

These feathers are entirely plumulaceous, making them soft and fluffy. Down feathers act as insulators that allow birds to manage their internal body temperatures by thermoregulation. There are 3 types of down feathers.

  • Natal Down temporarily covers the entirety of a hatchling’s body. Birds that are precocial (able to feed/tend to itself immediately after hatching, therefore not relying on a parent) tend to have more natal down since they have to maintain their temperatures on their own. Altricial birds (who rely on a brooding parent) have sparse natal down since they receive heat transferred by a parent.
  • Body Down lies under the contour feathers of many adult birds. These are more common in waterbirds such as penguins, loons, and ducks. Ever see a duck or goose line its nest with feathers? These are body down from their breast.
  • Powder Down are unique because they grown continuously and disintegrate at the tips to produce a keratinous “powder”. They help make feathers waterproof, and are only found in certain kinds of birds, such as pigeons and herons.

2. Contour Feathers

These feathers give a bird their characteristic shape and make up its exterior. The top section of these feathers are pennaceous, while the bottom section is plumulaceous. Many birds can use oil from the uropygial gland at the base of the tail to help their contour feathers repel water. Contour feathers have a variety of functions including aiding in thermoregulation, streamlining the body during flight, and social displays.

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Great Egret showing off its nuptial plumes (Image by BirdNation)

3. Flight Feathers

Flight feathers make up the majority of the tail and wing feathers. They are almost completely pennaceous. The anterior and posterior edges of flight feathers are asymmetrical. The leading edge (a.k.a anterior edge) is typically thinner than the trailing edge (a.k.a posterior edge).  This feature allows flight feathers to stabilize under the pressure of air currents during flight. These feathers are usually the stiffest and largest feathers on a bird. There are 2 types of flight feathers:

  • Remiges originate from the wings and attach to the bone. The feathers of the outer wing are called primaries and the feathers of the inner wing are called secondaries. The number of primary and secondary feathers vary by bird, but typically a bird can have between 9-12 primaries and 8-32 secondaries.
  • Rectrices  form the tail surfaces/airfoil of a bird. The central pair of rectrices attach directly to the tailbone. Like remiges, number of retrcies vary by bird size, but is typically between 6-32.

Coverts are smaller contour feathers that overlap the wing and tail feather and create the streamlined shape that is important to the aerodynamics of flight.

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The rectrices and remiges of a Bonaparte’s Gull (Image by BirdNation)

4. Semiplumes

Semiplumes are the intermediate form between the contour and down feathers. Their barbs usually lack hooks, so their vanes are not pennaceous. They occur at the edges of contour feather tracts and complement the insulation of down feathers.

5. Bristles

Bristles are highly specialized and lack barbs along most of its length. Their rachis are very stiff and they are almost exclusively found on a bird’s head. The most common type are rictal bristles, which commonly project at the beak’s base. Many birds that are insectivores, like flycatchers, have rictal bristles.

6. Filoplumes

Filoplumes are hair-like feathers and are the smallest of all the feather types. They have a rachis but few or no barbs. They’re usually hidden underneath the contour feathers. Instead of feather muscles, they have sensory receptors in their skin near the follicles. Filoplumes aid birds in detecting changes in feather position caused by body movement or wind.


Feathers are an amazing adaptation that is unique to birds. Knowing the types of feathers helps us appreciate how complex and special birds are.

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Hooded Merganser preening (Image by David Horowitz)

Eclipse Plumage

Today, August 21, 2017, was a big astronomical event: the first total solar eclipse seen over the United States since 1918. The path of totality went through 14 states from the Pacific to Atlantic Coast, while the rest of the states could view a partial eclipse. Here in New Jersey, we could only see a partial eclipse. I didn’t buy special eclipse glasses so I couldn’t watch it directly. I did however, watch a live stream of the eclipse from South Carolina State Museum, which happened to be in the totality path. It was extremely cool to watch.

Although the eclipse happened at a specific time today, many people don’t realize that an “eclipse” of sorts has been occurring the last few weeks. Have you gone to your local lake or pond and notice that it seems like the male Mallards are “missing”? Many ducks molt their feathers twice a year, one of these times being mid/late-summer. At this time they go into dull-colored basic plumage, or what is referred to as eclipse plumage. For reference, a male duck is called a drake and a female duck is called a hen. In eclipse plumage, drakes take on a hen-like appearance.

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Drake (male) Mallard in Eclipse Plumage (Image by BirdNation)

All birds molt their feathers at some point during the year. For many birds, this takes place after breeding season and before migration. Molting is when old worn out feathers are replaced by new feathers. Many species undergo was is called a sequential molt. During a sequential molt, birds lose one flight feather at a time from the innermost primary feather to the wing tip. This allows the bird the ability to still be able to fly. Waterfowl, however, undergo what is referred to as simultaneous wing molt. As a result, waterfowl loses all their flight feathers at the same time and therefore lose their flying ability. This period of being flightless can last between 20 and 40 days depending on duck species.

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Wood Duck male in Eclipse Plumage (Image via wikimedia commons by Meidosensei)

Eclipse plumage acts as a camouflage for these flightless drakes. The drakes molt their bright colored plumage first, which is replaced by dull brown feathers. This gives them the hen-like appearance. When it comes to Mallards, it could be hard to tell whether you are seeing a hen or drake in eclipse plumage. The trick is to look at the bill. Drakes have yellow bills while hens have orange bills with black markings. Eclipse plumage only happens for a few weeks. After eclipse plumage Mallards will  go into “alternate”  plumage for the fall/winter.

So even though the total solar eclipse is over, you can still see some eclipse plumage with the ducks at your local pond.

Have you been seeing any eclipse plumage drakes lately? And did you watch the solar eclipse? Tell me about these things in the comments!

Secret of the Stripes

Have you ever seen a White-throated Sparrow? White-throated Sparrows spend the winter in forested areas throughout many parts of the the United States in the winter. They are large gray-brown sparrows with long tails, yellow near their eyes, and head stripes. They seem like fairly simple birds, but did you know that their head stripes hold the key to their personalities?

I recently read an interesting article by author/naturalist Kenn Kaufman on Audubon’s website about the White-throats complex sex life. There are 2 morphs of White-throats: ones with white/black head stripes and ones with tan/dark brown stripes. (From this point forward I will refer to them as “white-striped” and “tan-striped”.) For many years scientists thought that the tan-striped birds were juveniles, but later learned that they are one of two permanent morphs.

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White-morph White-throated Sparrow at Boundary Creek (Image by BirdNation)

A lot of birds species have different morphs. Who cares, right? Well after much research (that is still ongoing), scientists have learned that these morphs determine a White-throat’s personality and their mating choices.

It may sound like a generalization, but tan-striped sparrows tend to more nurturing and white-striped tend to be more aggressive. Kaufman points out that these broad-sounding conclusions were made after numerous years of involved research. He sites multiple examples, such as white-striped of both sexes tend to sing more with a higher pitch, while tan-striped sing less often. Tan-striped live in denser forests and are not as aggressive with their territories, while white-striped live in more open woodlands and actively chase intruders.

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Tan-striped White-throated Sparrow morph (Image by Greg Lavaty via houstonaudubon.org)

Each morph is split pretty close to 50% male/female. Like they say with human relationships, opposites seem to attract in the White-throated Sparrow world. Studies found that pairs tend to consist of one of each morph. White-striped males with usually pair with tan-striped females, and tan-striped males with white-striped females.

Even though these pairings are common, White-throated Sparrows still have their own personal preferences. Females of both morphs prefer tan-striped males, and the more aggressive white-striped female tends to snag the tan males quicker. Males of both morphs prefer white-striped females. Tan-striped birds seem to stay monogamous longer, but white-striped may possibly be promiscuous.

Do the same morphs ever mate together? Studies find that around 95% of mating pairs will be these opposite morph pairs. More studies are needed to find out the results of same morph pairs, but there are some hypotheses of what might happen. It’s likely that a tan-striped nests could fail because of issues with defending their territories. White-striped nests could fail due to too much fighting with each other.

Studies on White-throated Sparrows are still ongoing, but the information we currently know about their complex social lives is fascinating. A bird species, such as White-throated Sparrows, may seem common, but many aspects of their lives are still packed with secrets that scientists are only starting to reveal.

If you’d like to read Kenn Kaufman’s article that was published on March 29, 2017 on the National Audubon’s Society website you can click on this link: The Fascinating and Complex Sex Lives of White-throated Sparrows

Mystery of the Red Feathers

Hi friends! Sorry I disappeared for a bit. Being a second-time college student and full-time music teacher, I am currently in the midst of finals and concert season, so it’s been pretty hectic around here. I’m hoping to be back to writing more frequently in the next few days.

Instead of doing the normal Woodpecker Wednesday profile post, I wanted to share an interesting woodpecker study. There was a woodpecker mystery that was recently solved by scientists. The mystery: red feathers in Yellow-shafted Northern Flickers. The answer was not what scientists were expecting.

The Northern Flicker is the most abundant woodpecker in North America. Although pretty common, they are probably the most unusual of woodpeckers. They mainly feed on the ground on ants, are weak tree excavators, and even roost in trees less than other woodpeckers. Another unique feature is their intricate plumage, which is brown and tan or light peach, with black belly spots and a “zebra-back”.

When John Jame Audubon first saw Northern Flickers in 1843 at Yellowstone, Wyoming he was puzzled. He saw five Northern Flickers that all varied dramatically in plumage color. Some were red, some were yellow, and other were in between. He didn’t know it at the time, but he was in what is now considered “the hybrid zone”.

There are two subspecies of Northern Flickers: the “Red-shafted” Flicker of the west and the “Yellow-shafted” Flicker of the East. They frequently hybridize in the Great Plains region of the United States, south to Texas and north to Canada. This hybrid zone is at least 4,000 years old. Unless you live in the hybrid zone, you are most likely to see either one subspecies or the other.

Over a century later, scientist were puzzled one again about Flicker plumage. Starting the the 1960s, some biologists began to notice that there were Flickers over a 1,000 miles east of the hybrid zone with red feathers. But there weren’t quite as bright as the western “red-shafted” plumage, they were more of a copper color. Some ornithologists speculated that the color was being cause by genes from the red-shafted being spread to the yellow-shafted population. Something wasn’t quite right with that explanation though, so studies continued.

But now the mystery is solved! A recent study published on October 12, 2016 in The Auk revealed what was causing the color change. And it turns out hybridization has nothing to do with it.

The answer: honeysuckle berries.

Red-shafted Flickers have red feathers because of 4-keto-carotenoids, a type of pigment. The “red” Yellow-shafted Flickers get their color from a pigment called rhodoxanthin. Rhodoxanthin is rare in the wild and only found in certain plants. By eating berries from honeysuckle plants, particularly the Morrow’s, Tartarin, and their hybrid Bell’s honeysuckles, they are ingesting this pigment. These “red-yellow” Flickers are eating this food source around when they molt and acquire new plumage.

So why did it take scientist so long to solve this mystery? The Northern Flicker’s diet consists heavily of ants and other insects. Since berries is a smaller portion of their diet, the pigment they are eating is usually not as obvious, so it took scientists a longer time to notice.

Although this mystery is solved for the moment, there are so many other ornithological enigmas to the study (how about the mystery of the Ivory-billed Woodpecker?). But that’s the great thing about ornithology and other biological sciences: there are so many fascinating and exciting discoveries just waiting to be found.

If you want to read the actual study you can read it here:

The Auk Ornithological Advances

What kind of Northern Flickers do you see? Tell me about them in the comments.

 

 

 

Meet the Feet

A few weeks ago I was researching some interesting facts for my post World of Woodpeckers. One of the featured facts was that woodpeckers have two forward and two backwards-facing toes, making their feet zygodactyl. I already knew about the toe directions, but was unfamiliar with the term zygodactyl, so i googled it.

That’s when a whole new world opened up for me: the world of bird feet. It’s not a topic that normally comes up in conversation, but bird feet are pretty amazing. There are different kinds of feet throughout the avian world. They serve a variety of functions and tell a lot about a bird’s ecology.

Functions of avian feet include perching, locomotion, preening, feeding, carrying/holding objects, scratching, reproduction (egg rolling, displays), and heat loss regulation.

Birds are animals that are considered digitigrade. This means that they generally walk on their toes, not on their entire foot like we do. Most birds have have 4 toes, or digits, although some only have 3. Bird digits can be arranged in a few different ways.

Anisodactyl

Anisodactyl feet are the most common digit arrangement in the bird world. This means that digit number 1 (which is similar to our big toe) faces backwards and the other 3 digits face forwards. This digit arrangement is found in passerines, or perching birds. Anisodactyl feet are extremely flexible because all four digits are independent. Therefore, digit 1 can be flexed to lock the toes around a perch. That’s why you don’t see birds falling out of trees when they sleep on a branch!

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Anisodactyl foot (Image via kidwings.com)

Zygodactyl

On zygodactyl feet, digits 1 and 4 face backwards while digits 2 and 3 face forward. This kind of foot in common in woodpeckers, most parrots, owls, and some other species. The shape of these feet help a bird climb up, down, and along the trunk of a tree. Parrots use their feet to hold food and bring it to their bill, in the same way that we use our hands to eat. Owls have zygodactyl feet to help them hold their prey and perch. Something unique about owls is that they can rotate their 4th digit forward.

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Zygodatcyl foot (via Ferbank Science Center, Atlanta, GA)

Webbed Feet

There are 4 kinds of webbed feet, with the most common being Palmate.

  • In palmate feet, digit 1 is backwards and digits 2,3, and 4 are connected by webbing. Examples include ducks, geese, gulls, terns, loons, and other aquatic birds.
  • Semipalmate feet are found in sandpipers, plovers, herons, grouse, and avocets to name a few. These feet are similar to palmate but the webbing is smaller.
  • Lobate feet have a backwards digit 1 and digits 2,3, and 4 have lobes of skin surrounding them. A few species with lobate feet include coots, grebes, and phalaropes.
  • Totipalmate feet have all four digits connected by webbing. Some totipalmate birds are pelicans, cormorants, anhingas, boobies, frigatebirds, and gannets.
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Kinds of webbed feet (Image via wikimedia commons by Darekk2)

Raptorial

Raptorial feet are found in birds of prey (raptors). The toes of these feet are called talons. They are curved with sharp nails, strong, and large. These kind of feet make raptors lethal hunters.

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Bald Eagle talons (Image via pinterest.com)

Other (more uncommon) Feet

  • Pamprodactyl feet have the 4 digits facing forward. However, the two outer digits (1 and 4) can be rotated backwards. This kind of foot is found in swifts.
  • Another toe arrangement that is similar to zygodatcyl is heterodactyl. There are still 2 forward and 2 backwards, but instead digits 1 and 2 are backward and 3 and 4 are forward. This arrangement is only found in trogons.
  • Syndactyl feet are found in Kingfishers. Digits 2 and 3 are fused together and digit 1 is very small and backwards.
  • Didactyl feet are only found on ostriches. Didactyl means “two-toed”. The shape of this foot is similar to a horse’s hoof, so having along two toes aids in running and escaping predators.
  • Tridactyl feet have only three digits, digit one is missing. Tridactyl birds include emus,.bustards, the Northern Three-toed Woodpecker, and quails.

The anatomy of birds is a broad and fascinating subject. There are over 10,000 birds species and so many variations/adaptations to learn about. I hope to present more bird anatomy posts in the future.

In the meantime, if you have any specific birds or topics you would like to know more about please let me know in the comment section.