Thursday, April 19, 2018

Avian Influence and the Shaping of their Surrounding Environment

The evolution of flight is one of the most striking and demanding in animal evolution. Powered flight has evolved only four times—birds, bats, pterosaurs, and insects. In contrast to gliding, which has evolved more frequently but typically gives rise to only a handful of species, all three extant groups of powered flyers have a large number of species, suggesting that flight is a very successful strategy once evolved (source: Wikipedia).

I’m reminded of this strategy most during the month of August as I stroll through my backyard, admiring the flowering plants in and around the garden and ponds. Here I easily find dragonflies, butterflies, moths, various insects, birds, and at dusk, what is left of our bat population.

This Blogs Author Hummingbird and Butterfly Gardens
Photo Credit: Paul Cianfaglione
Female Blue Dasher Dragonfly
Photo Credit: Paul Cianfaglione
But here its only mid-April, and I am once again contemplating animal flight. This time however my interest is roused by an audio-DVD called A New History of Life, produced by a company called The Great Courses.

A New History of Life; The Great Courses
Photo Credit: Paul Cianfaglione
The lecture I was listening to on the way to work titled; Conquering the Air-The Evolution of Flight, cited an unusual occurrence between birds and bats, some 52 million-years-ago during the Eocene period.

It was suggested that bats were driven into a nocturnal existence by the rapid evolution of competing birds during that same time period. Proof of this is found in the Green River Formation bat fossil Onychoycteris finneyi, which had well-developed wings to fly, but lacked the enlarged cochlea of all extant echolocating bats. Were bats diurnal creatures prior to being forced into using echolocation and nocturnal hunting habits? It’s certainly a theory to strongly consider.

Onychoycteris finneyi
Image Property of: Wikimedia Commons
This idea had me thinking about my own local birds, and their impact on other surrounding organisms. Is it possible to detect these influences in nature with the naked eye? The answer is yes.

A leading example of this is the contrasting black and orange wing pattern of the Monarch Butterfly, which warns insectivorous birds of their undesirable taste and poisonous nature. Monarchs are foul tasting and poisonous due to the presence of cardenolide aglycones in their bodies, which the caterpillars ingest as they feed on milkweed.

Monarch Butterfly Caterpillar eating milkweed
Photo Credit: Paul Cianfaglione
Monarchs share the defense of noxious taste with the similar-appearing Viceroy Butterfly in what is perhaps one of the most well-known examples of defensive mimicry.

Monarch and Viceroy comparison
Other species of butterflies lack those toxic defenses altogether, and as a result, are often attacked and sampled in the process.

Fritillary with bird damage on wing
Photo Credit: Paul Cianfaglione
Some moths have even gone to the length of masquerading themselves as a pile of bird droppings to avoid detection. These changes have occurred incrementally over millions of generations, forced by the visual hunting of many birds.

Schlaeger's Fruitworm Moth 
Photo Credit: Paul Cianfaglione
Another way birds have had direct influence over other organisms is with the drone fly Eristalis tenax, which looks identical to a drone honey bee, and likely gains some degree of protection from this resemblance to a stinging insect. Like other hover flies (I like to refer to them as bee mimics), they are common visitors to flowers, especially in late summer and autumn, and can be significant pollinators.

Eristalis tenax; honey bee mimic
Image Property of:
Even the Trumpet Creeper (Campsis radicans) vine climbing over my patio trellis is impacted by the presence of birds. Some scientists believe that as many as 19 species of plants found in the eastern United States have co-evolved with hummingbirds, noting the relationships between the tubular shape of certain flowers and the length and shape of a hummingbird’s bill (source: The Ruby-throated Hummingbird (Archilochus colubris) efficiency as a pollinator is comparable to that of a honey bee.

Ruby-throated Hummingbird (Archilochus colubris) on Trumpet Vine Flower
Photo Credit: Paul Cianfaglione

Tuesday, April 17, 2018

Dinosaurs and Birds; The Age of the Dinosaurs, Volume 5. A Pictorial Book Review.

One of the best places that I have discovered to learn about dinosaur-to-bird evolution has been in the children’s section of our local libraries. With three kids in tow, our weekly visits to these reading rooms has afforded me time to peruse a selection of children book shelves, and in the process, helped us gain a fond appreciation for them all together.

The book I’m reviewing today is titled; Dinosaurs and Birds; The Age of the Dinosaurs, Volume 5, by Steve Parker.

Dinosaurs and Birds; The Age of the Dinosaurs Volume 5, by Steve Parker
Photo Credit: Paul Cianfaglione

Published in 1999, Dinosaurs and Birds; The Age of the Dinosaurs is part of a twelve-volume set that features additional titles such as Origins of the Dinosaurs, The Early Dinosaurs, Dinosaur Cousins and Dinosaur Pack-Hunters.

Though intended for a middle-school audience, Dinosaurs and Birds defies being properly cataloged based on its information alone. This is important to know, since many librarians consider dinosaur books more of a kid’s specialty. Its sixty-pages include important chapters on “where did birds come from, similarities and differences, the origin of flight, hollow bones, Compsagnathus skeleton, a feathered dinosaur, warm or cold blood, and the disappearing tail”.

Dinosaurs and Birds; The Age of the Dinosaurs Volume 5, by Steve Parker
Photo Credit: Paul Cianfaglione
Dinosaurs and Birds; The Age of the Dinosaurs Volume 5, by Steve Parker
Photo Credit: Paul Cianfaglione
The design of the book is clearly envisioned for the younger eye, yet it could also spark the interest of an older adult, just now being introduced to this fascinating subject.

Dinosaurs and Birds; The Age of the Dinosaurs Volume 5, by Steve Parker
Photo Credit: Paul Cianfaglione
Visually, the pages of this book are busy, but busy in a tastefully done manner. In addition to some very well researched information, each chapter is accompanied by outstanding paleoart, line diagrams, photos of actual fossils, museum dioramas and modern bird images.

Dinosaurs and Birds; The Age of the Dinosaurs Volume 5, by Steve Parker
Photo Credit: Paul Cianfaglione
I especially enjoyed the side-bar facts, which again, seem appropriately targeted to both teen and adult alike. However, not so much for the child less than ten years of age.

Side-bar discussions include the dinosaur/bird mosaic, finer parts of the feather, body muscle, the furcula and prehistoric bird findings and groupings. These topics up the ante intellectually, making Dinosaurs and Birds an important, and still relevant reference for today’s young inquiring minds.

Dinosaurs and Birds; The Age of the Dinosaurs Volume 5, by Steve Parker
Photo Credit: Paul Cianfaglione
Dinosaurs and Birds; The Age of the Dinosaurs, Volume 5 is also remarkable given the time that it was published, a time (1999) that is arguably one of the most important in our understanding of bird evolution today. From newly discovered feathered dinosaurs in China, to a clearer insight of how and why feathers evolved, Dinosaurs and Birds was a worthy representation of the days science. For me, this book is must-have collector item for anyone with a strong interest in the history of dinosaur-to-bird evolution. A fun book to look back on.  

Strangely enough, at the time of this review, I was also in the middle of reading the BBC Focus Magazine Collection on Dinosaurs (2017). About midway through the magazine, it dawned on me, “this modern-day journal is identically designed to the 1999 Dinosaurs and Birds book!” How ironic. I guess this type of “layout” has now evolved enough over time to appeal to a greater audience!

BBC Focus Magazine Collection Dinosaurs 2017
Photo Credit: Paul Cianfaglione

BBC Focus Magazine Collection Dinosaurs 2017
Photo Credit: Paul Cianfaglione

Friday, April 6, 2018

Avian Caudofemoralis Muscle

Crows and ravens are well known for their intelligence and complex social arrangements. Corvids, as they are collectively branded, invariably know the best times of the day to take advantage of human activities.

Empty shopping mall parking lots strewn with garbage and food are largely visited in the early morning hours, prior to the arrival of unwelcoming employees and cars. 

They have incredible memories which allow them to recognize human faces. This bodes well for a person like me who likes to spend time (at shopping malls!) observing their own behavior. In time, my familiar face, and car, allow for special up-close interactions.

American Crow (Corvus brachyrynchus)
Photo Credit: Paul Cianfaglione
One of these unusual behaviors that I have taken a keen interest to deals with the way American Crows (Corvus brachyrynchus) generally walk.

Unlike many smaller birds that employ short quick hops while ground feeding, the crow uses an animated waddle-walk as it searches for food.

American Crow (Corvus brachyrynchus) rolling gait
Video Credit: Paul Cianfaglione
Click on video here; 

Corvids spend as much of their time on the ground, as they do in the air. This is nicely supported by the structure of their feet, which exhibit a variety of tough protective plating of scales (also called scutes).

American Crow (Corvus brachyrynchus) foot 
Photo Credit: Paul Cianfaglione
But their unusual walk is not caused by this collection of plating, rather, its caused by a muscle called the caudofemoralis.

The purpose of the caudofemoralis is to retract the femur (extend the hip joint), drawing the leg backwards, in much the same way a crocodile uses the same set of muscles attached to its tail. 
Avian Caudofemoralis Muscle
Image from Manual of Ornithology by Noble S. Proctor 
In birds, the caudofemoralis is often described as strap-like, attaching to the ventral surface of the pygostyle area, to an insertion on the femur marked by the fourth trochanter. The strap-like condition (highly reduced) is probably related to the evolution of forelimb powered flight and the need to minimize weight (source:

In the evolution from dinosaur to bird, we see a reduction in not only the tails, but the fourth trochanter as well. This is an evolutionary trend of derived features that support the placement of birds in dinosaurs (source:10/8/05 Richard Prum - The Evolution of Birds: Why Birds are Dinosaurs

Yet, I still find it hard to believe that a muscle, which is endlessly characterized as stunted or nearly useless, is responsible for such an animated and forceful behavior. 

Crows I know walk a lot. I follow and photograph their trails in winter as they trudge through deep snow, one foot directly in front of the other. In my opinion, the caudofemoralis muscle must still play a significant role in their pedestrian locomotion, contrary to what authorities have led us to believe; and the crows femur should tell us that.

American Crow Tracks in Snow
Photo Credit: Paul Cianfaglione
Thankfully, I have at my disposal an American Crow femur, and the femur from a small theropod dinosaur from Morocco for direct comparative study.

American Crow (Corvus brachyrynchus) Femurs
Photo Credit: Paul Cianfaglione
Initially, and to my utter disappointment, the crow femur showed little in the way of a bumpy muscle scar along its shaft. The small theropod femur on the other hand did exhibit a significant fourth trochanter for the connection of a large caudo-femoral muscle.

Theropod Femur
Kem Kem beds, Morocco
Photo Credit: Paul Cianfaglione
However, further inspection of the crow femur did subsequently reveal a noticeable protrusion coming from an area called the obturator ridge, which seemed to be a promising site for an attachment. But was this at all possible? 

Avian Femur Obturator Ridge
From book Avian Osteology by Gilbert, Martin, Savage
Photo Credit: Paul Cianfaglione
It turns out it is. Gary Kaiser’s book, The Inner Bird, Anatomy and Evolution, clearly mentions the ridge for this exact purpose;

*Where dromaeosaurs had a trochanter on the back of the femur for the attachment of the caudal-femoral muscle, birds have a long, low structure called the obturator ridge*.

Long and low is not how I would have described our crow’s obturator ridge, but at least I felt like I was getting somewhere with this inquiry.

American Crow (Corvus Brachyrynchus) Obturator Ridge
Photo Credit: Paul Cianfaglione
American Crow (Corvus brachyrynchus) Obturator Ridge
Photo Credit: Paul Cianfaglione
Fossil footprints sparked an early interest in the ability of dinosaurs to run and walk, playing an important role in shifting opinion from dinosaurs as sluggish reptiles to dinosaurs as active animals. Examination of the implications of bipedal locomotion is a more recent event (Kaiser).  

Kaiser goes on to nicely compare dinosaur and bird locomotion here;

*The bodies of bipedal dinosaurs were far more sophisticated but also functioned as a single locomotor module, in part because their forelimbs abandoned a role in locomotion for new responsibilities in the capture of prey while their bodies still moved as an integral unit. When such a dinosaur walked, it needed to shift its weight onto the supporting leg and would have rocked from side to side as it moved forward. To keep its balance, it needed to make compensating movements with the head and tail. We can still see echoes of the dinosaur’s rolling gait in walking birds. Most small modern birds hop about on the ground but crows and other larger species often walk, swinging their tail back and forth. The tip almost, but not quite, touches the ground, as though the weight of the feathers could counterbalance the lightweight bird just as a massive, fleshy tail would have counterbalanced Tyrannosaurus rex*.    

Finally, for those of you interested in the theropod femur, it hails from the 95 million-year-old Kem Kem beds of Morocco. It measures 85mm long. The ‘Kem Kem beds’ of Morocco have yielded abundant material of large bodied theropod dinosaurs, but remains of small theropod taxa are rare. For more information on small Moroccan theropods, please see here;

Sunday, April 1, 2018

Malaysian rail-babbler (Eupetes macrocerus). All Birds Considered

Inspired by David Attenborough’s book, The Life of Birds, is a monthly spin-off segment of my blog called “All Birds Considered”, which I hope will bring attention to some of the more unusual, and lesser known birds of our world.

The Life of Birds by David Attenborough
Photo Credit: Paul Cianfaglione

Species; Malaysian rail-babbler (Eupetes macrocerus)

Malaysian rail-babbler (Eupetes macrocerus)
Image Credit: Wikipedia
Introduction; The Malaysian rail-babbler (Eupetes macrocerus) is a strange, rail-like, brown and pied ground living bird. It is the only species in the genus Eupetes and family Eupetidae. It lives on the floor of primary forest in the Malay Peninsula and Sumatra (the nominate subspecies macrocerus), as well as Borneo (ssp. borneensis), distantly related to African crow-like birds. Its population has greatly decreased because much of the lowland primary forest has been cut, and secondary forests usually have too dense a bottom vegetation or do not offer enough shade to be favourable for the species. However, it is locally still common in logged forest or on hill-forest on slopes, and probably not in immediate danger of extinction. The species is poorly known and rarely seen, in no small part due to its shyness.

Malaysian rail-babbler (Eupetes macrocerus)
Image Credit:
Description; 28-30 cm. Long slender appearance, broad white eyebrow, black band on side of head, rufous-buff forehead, and chestnut crown, nape and throat diagnostic. Patch of bare blue skin of neck sometimes visible. Rest of plumage rufescent olive-brown, more rufous on wings and tail, the breast with a heavy rufous wash. Bill black.

Voice; A low-pitched monotone whistle lasting 1 ½ seconds, a rich frog-like “goink” uttered in an irregular series of about 4 per second.

Behavior; It is a shy and secretive bird, which lives on the forest floor. It walks like a rail, jerking its head in the manner of a chicken, and it prefers to run rather than fly when disturbed. It feeds mainly on insects, including cicadas, and beetles; spiders and worms. When feeding it will dash after prey items. Little is known about its breeding habits. The eggs are laid around January and February and fledgeling have been seen in June. The nest has been described as being placed near the ground on a pile of dead leaves among the stalks of a plant around 30 cm (12 in) from the ground. It is made of plant fibers and is a cup shape. The clutch is two white unmarked eggs, nothing else is known.

Watch the Malaysian rail-babblers extraordinary behavior here;

*An excerpt from the book; The Life of Birds – Not available


Birds of South-East Asian, Collins Field Guide. 1975


The Life of Birds (1998) David Attenborough