A bird’s lifestyle is written in its wings.

Birds who fly fast and maneuver quickly, such as peregrines and swifts, have narrow pointy wings built for speed and agility.  They need this equipment to capture prey in the air.

Birds who soar slowly in search of food, such as red-tailed hawks and turkey vultures, have broad wings with a lot of surface area.

Broad, blunt wings create a lot of wingtip turbulence (remember those vortices?) so soaring birds have feather slots at their wingtips.  This confers two flight advantages.

First, each feather stands alone like a tiny pointy wing with a high aspect ratio (ratio of length to breadth) that’s more like a peregrine’s wing.   The winglets create less turbulence and therefore less drag.

The second advantage is in the gaps. As air is forced upward between the feather slots, it expands on the upper side creating low air pressure on top and therefore more lift.

Turkey vultures are masters of slow speed flight.  They turn and teeter without flapping — not even once!

The slots help them fly.

(Photo by Chuck Tague.  Today’s Tenth Page is inspired by page 120 of Ornithology by Frank B. Gill.)

We see chicken eggs every day so we tend to assume all eggs are plain and never shiny.  In reality most eggs are not.

Shown above is an illustration of 50 European bird eggs by Adolphe Millot published 1897-1904(*).

The eggs have many shapes and sizes from the goldcrest’s tiny pink oval (#19) to the large pointed pyriform egg of the now extinct great auk (#47).

Few are a single solid color but even those are amazing — from pink to robin’s-egg blue to a beautiful avocado color.  Tinamous are from South America so their eggs aren’t pictured here, but it’s worth clicking this link to see their glossy eggs in several colors.

The dark patterns on eggs are almost fanciful wreaths, caps, scrawls, dots, streaks and blotches.  They’re made by protoporphyrin which is deposited within or on the shell while in the bird’s uterus.  These dark spots are stronger than the plain calcium shell and tend to be deposited where the eggshell is thinnest.  Some birds lay on extra protoporphyrin when their personal calcium supplies are low.

And, as a final touch some eggs are shiny, some are waterproof.  I have read that duck eggs feel oily and that jacanas, who build floating nests, lay eggs that are lacquered (#29, in the top row).

Explore the eggs in the illustration using the quick key below.  If you click on the image you can zoom the original to read the egg numbers.

(Credits:
Illustration of European bird eggs from “ŒUFS” (Eggs) by Adolphe Millot from Nouveau Larousse Illustré [1897-1904], in the public domain via Wikimedia Commons.  (*) This image has been altered as described in the “p.s.” below.  Click on the image to see the original.
Inspiration for this Tenth Page is from an illustration on page 400 of Ornithology by Frank B. Gill.)

p.s.  Key to the illustration, copied from Wikimedia Commons:
The original French designation may not correspond to the modern French term. Eggs 1-50 are bird eggs, reduced in size by about a third.  Eggs 51-72, (*)which I erased from this illustration, were from turtles, reptiles, moths etc. I erased them to highlight only the bird eggs.  Click on the image above to see the complete original on Wikimedia Commons.

#    French        English
1    De bondree    honey buzzard (?)
2    De faucon    falcon (?)
3    D'epervier    Eurasian sparrow-hawk
4    De merle    blackbird
5    De grive    thrush
6    De freux    rook
7    De bruant proyer    corn bunting
8    De gros-bec    hawfinch (or perhaps another grosbeak?)
9    De moineau    sparrow
10    De pinson    chaffinch (or other finch?)
11    De pitpit    pipit
12    De bruant des roseaux    reed bunting
13    De coucou    cuckoo
14    De petit oiseau-mouche    hummingbird (?)
15    De bec-croise    crossbill
16    De troglodyte    wren
17    De sittelle    nuthatch
18    De rossignol    nightingale
19    De roitelet    Kinglet (Goldcrest?)
20    D'accenteur    accentor
21    De bruant fou    rock bunting
22    D'effarvate    reed warbler
23    De rousserolle    sedge warbler (or other Acrocephalus?)
24    De fauvette    warbler (??)
25    De mesange    tit (?)
26    D'hypolais    tree warbler
27    De jaseur    waxwing
28    De loriot    oriole
29    De jacana    jacana
30    De grouse (?)    grouse (?!)
31    De lagopede    lagopus
32    De faisan    pheasant
33    De perdrix    partridge
34    De caille    quail
35    D'avocette    avocet
36    De chevalier arlequin    spotted redshank
37    De pluvier guignard    dotterel
38    De pluvier de Virginie (??)    plover (??)
39    De vanneau    lapwing
40    De chevalier cul-blanc    green sandpiper
41    De sterne hybride (??)    tern (??)
42    D'hirondelle de mer    common tern
43    De sterne de Ruppell (??)    tern (??)
44    De goeland    seagull
45    De plongeon    loon
46    De guillemot    guillemot
47    De grand pingouin    great auk
48 & 49    De macareux    puffin
50    De grebe    grebe

Avian Reproduction reference

Feathers are to birds as hairs are to mammals .. but not quite.

Here are some feather facts to ponder.

• Feathers, like hair, are dead structures that have no nerves and cannot change or heal themselves if damaged.
• Our hair grows continuously.  Feathers grow to completion and then stop, so they must be replaced when worn out.
• The follicles that hold feathers in the skin have muscles that grip the feathers so they don’t fall out.  Anyone who’s plucked a chicken knows these muscles are strong.
• In some birds, such as nightjars, the follicle muscles let go when the bird is frightened suddenly.
• A new feather literally grows under the old one and pushes it out of the follicle.
• Contour (body) feathers are symmetrical and so are their follicles.  Flight feathers are lopsided: narrow on one side of the rachis (shaft) compared to the other.  Flight follicles are lopsided too.
• The same feather follicle can produce differently colored feathers at different times of year — for example colorful feathers for the breeding season and drab ones for basic plumage.  Imagine if our hair could do that! We could automatically change our hair color in the spring.

Resources: Anatomy: Parts of a Feather.

(Inspiration for this Tenth Page is from page 90 of Ornithology by Frank B. Gill. Photo from Wikimedia Commons; click on the image to see the original)

Last week I wrote about the Urvogel Feather of Archaeopteryx lithographica, the oldest feather ever found.  Now that I’m beginning the Tenth Page series I’ve discovered that page 30 of Ornithology has a neat comparison of Archy’s skeleton to that of modern birds.

Archaeopteryx lithographica is recognized as a link between dinosaurs and birds because he has features of both.  Like dinosaurs he has**:

• jaws with sharp teeth
• three fingers with claws
• a long bony tail
• hyperextensible second toes that are “killing claws”
• feathers, which also suggest homeothermy (This characteristic is rather self-fulfilling in that dinos were not thought to have feathers until Archy was discovered.)
• and various dinosaur skeletal features.

Like birds he has:

• flight feathers, the asymmetrical feathers on his wings
• broad wings
• hollow bones
• a furcula, the “wishbone”
• and reduced fingers.

But as a bird he’s not quite there yet.  Modern birds have skeletal adaptations that make flight much easier than it must have been for Archy.  This is evident in a skeletal comparison.

Page 30 of Ornithology describes how modern birds improved on Archaeopteryx lithographica’s features:

1. Skull: In modern birds the braincase is expanded and the bones are fused.
2. Hands: Most of the bones are fused
3. Pelvis: Bones are fused to make a sturdier structure
4. Tail: Bones are fused, the tail is shorter
5. Sternum: Expanded to a large keel for attaching the flight muscles
6. Rib cage: Has cross-struts (“horizontal uncinate processes”) for strength.

So, if you have a lot of time to improve your flight abilities — say 150 million years — this is what you get.

Inspiration for this Tenth Page is from page 30 of Ornithology by Frank B. Gill.

(credits:
** The dino list is quoted from the Wikipedia article on Archaeopteryx.
Photo of Archaeopteryx lithographica, Solenhofener specimen from Wikimedia Commons.  Skeleton of modern bird from Illustrations of Zoology by W. Ramsay Smith and J S Newell, in the public domain via Wikimedia Commons, red annotations added by Kate St. John.  Click on the images to see the originals.)