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)

The Warbler Guide

Dave and I were getting ready to go on a birding trip. We were going to Hawk Mountain, so I wanted to bring our small Canon camera instead of the DSLR since it’s easier to carry around. Dave usually keeps the Canon in his sock drawer, in the left corner right on top. I opened up the drawer, but the camera wasn’t there. I started pushing socks around.

And then there it was. Nope, not the camera. The Warbler Guide. The book that Dave and I were looking at in Barnes and Nobles a few weeks earlier.

My first thought was Oops. I found my Christmas gift.”  I felt slightly panicked. Then my second thought was one of excitement: “He bought me The Warbler Guide!” . I realized I had to try and act cool to pretend that I didn’t find the book. So I quickly closed the drawer said “Hey Dave, I can’t find the camera, can you help me find it?” I started petting our cat Jenny who happened to be sitting nearby to try to take my mind off of what I found. It was hard to contain my excitement. I guess I did a pretty bad job of it because a few minutes later Dave asked, “Did you see something in my drawer?”

I admitted that yes, I did find the book. He told me that I could have it early since he planned on getting another thing for Christmas too. Dave and I can never actually wait until the holiday to give each other gifts anyway (we get too excited and can’t keep the secret) so we always give gifts early. I’ll consider it a Thanksgiving gift lol :-).

The Warbler Guide is amazing. Written by Tom Stephenson and Scott Whittle, it won a National Outdoor Book Award in Nature Guidebooks in 2014. If you are serious about learning to identify North American warblers, then this is the book for you. This guide is extremely detailed. I am already in love with it.

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The first section of the book is called “What to Notice on a Warbler”. This section focuses color and contrast, behavior, the face, the body, and the undertail . There are many pictures to help explain the key identification points. One of my favorite parts of this section is “the face”, where the authors goes deeper into significant facial features such as eye rings, cheek patches, superciliums (a.k.a the “eyebrow”), and more.

Another section is titled “How to Listen to Warbler Songs”. This section explores the elements that create warbler songs. The authors use audio spectrograms (a.k.a sonograms) to show harmonics, song stucture, and phrases. This chapter explains in detail how to read the spectrograms, but later in the book you can explore the spectrograms of each individual species in this book.

The largest section of this guide is the individual species accounts. Instead of putting the warblers in taxonomic order like other field guides, the authors decided to put the birds in alphabetical order. They explained in the beginning of the book they did this because the taxonomy of warblers has significantly changed recently, and some of the warblers in question are still not settled. The authors also felt it would be easier to find the warbler you need if the birds were listed alphabetically.

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Example of a Species Account (Tom Stephenson and Scott Whittle, published by Princeton University Press)

Each species accounts are about 3-6 pages long with numerous pictures. Information provided includes physical descriptions, range maps, photos of distinct views/many additional photos, comparison species (with photos), aging and sexing, and spectograms (with comparison to other species). There are a few features in each account that you usually don’t see in other field guides such as undertail patterns, preferred habit in trees (high canopy, understory, ground, etc), a color diagram, and behavior icons. All this information is easy to read and well organized.

Other great features of this book include quizzes to test you id skills, habitat and behavior charts, a taxonomy chart, descriptions and diagrams of flight patterns, silhouettes broken down by region, and species accounts of similar non-warbler species.

My favorite feature is the “quick finder section”. The quick finder section are all illustrations. The “quick finders” include faces, side views, 45 degree views, under views, seasonal plumage views, types of undertails, and song finder charts.

The Warbler Guide has a wealth of information for serious birders. It’s well organized and has hundreds of great pictures to show key identification parts. There’s a website listed in the back of the book where you can access additional resources. You can also purchase for iTunes the audio tracks that are featured in the book, so you can study the spectograms while listening. I think it’s an essential book for anyone who wants to explore the wonderful world of North American Warblers. I can’t wait to devour the information in this book.

And who knows, this may be the perfect gift for the warbler lover in you life. Just make sure you hide it better than Dave did :-P.

 

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.