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African Harrier Hawk (Polyboroides typus)
The African harrier hawk is one of only two birds of prey that has double-jointed knees. It uses these joints to hunt animals in cracks and holes in cliffsides and trees. One of its favored foods is the sociable weaver (Geranospiza caerulescen), which creates massive nests with other members of its species. Nom nom nom.
Album of Abyssinian Birds and Mammals. Louis Agassiz Fuertes, 1928.
Egretta thula - Snowy Egret
These little white herons were nearly wiped out, because of the high demand for their snow-white, shaggy, flashy, breeding plumage - the fashionable High Victorian lady always had a base of fluffy heron feathers in her hat, highlighting the colorful centerpiece-feathers.
Portraits and Habits of our Birds: National Association of Audubon Societies. Edited by T. Gilbert Pearson, 1921.
Egrets are just herons with white plumage. Unfortunately, most of them were hunted by the millions in the early 1900s for “fashion,” but some, including the snowy egret, are increasing in population these days.
My favorite creatures have some beautiful bones.
Die/Das Skelete [series]. Dr. E. D’Alton, 1821.
Things you probably have never thought about:
Comparative anatomy of bird tongues. We all learn about the different beaks of birds relating to the foods they eat as kids, but the tongue can play almost as much of a role in determining a birds diet as the beak does. The stumpy, near-nonexistent tongue of a kingfisher doesn’t impede catching and swallowing fish whole. The long and agile tongue of a hummingbird is a tube that ends in two curled troughs to sip nectar. The spear-like tongue of a woodpecker is perfect for snagging insects in tree bark, and the well-padded tongues of seed-eaters allow them to manipulate seed hulls without getting hurt.
Tongues from On the Anatomy of Vertebrates: Vol II - Birds and Mammals. Richard Owen, 1866.
American Crow - Corvus brachyrhynchos
Both the American crow and the common raven (Corvus corax) are widespread, highly adaptable, and have loud and distinctive calls. Their conspicuous and ubiquitous nature made them two of the most commonly identified species in cemeteries, graveyards, and other areas associated with death and despair.
Unfortunately, the specter of death seems to have caught up to the crows - since 1999, the population of crows has dropped by over 45%, thanks to West Nile Virus. Despite the adaptability of the birds, they’re very susceptible to many avian diseases. As such, they’re considered a bioindicator (or sentinel) species - when they start dying in larger numbers, it indicates the presence of WNV or another avian disease in the area, and other birds will probably start dying soon.
The living animals of the world. C. J. Cornish, 1902.
He judges us all.
Adélie penguin - Pygoscelis adeliae
Wild geese in the sky above a Wisconsin lake. The Educational screen. November 1941. Cover art.
Condor Vulture [Andean Condor - Vultur gryphus]
Andean Condors subsist almost completely on carrion, and unlike some vultures, are not inclined to hunt and kill fresh prey. However, as the largest flighted bird, one can almost see where the fear of infant abduction would come about.
Arcana: Or, The Museum of Natural History; Containing the Most Recent Discovered Objects. George Perry, 1811.
Feathers
Found only on birds, feathers are some of the most complex integumentary (skin) structures found in vertebrates.
There are two primary types of feathers: flight and down. Some birds, such as peacocks and birds-of-paradise, also have display feathers.
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Flight feathers come in two categories of their own: remiges (wing feathers), and rectrices (tail feathers). These strong feathers are what allow most birds to fly. They have strong midline ridges, called the shaft (or rachus). The rachus is mostly covered in the fluffy-but-structured extensions, what most people think of as the “feather”, called the vane. At the bottom of the rachus, below the vane, is the bare quill (or calamus). Each extension on the vane is covered in many hooks and hooklets (also called barbs and barbicels), which is what birds are putting back into place when they preen - gotta keep everything in order to fly well!
Down feathers don’t have the hooks or the rachus of the flight feathers. There are many types of down feathers, but all of them serve the same basic purpose, which is temperature regulation. They trap air close to the bird’s body, which insulates it from the cold. When a bird puffs up in the middle of winter, it’s creating a bigger insulating layer to trap body heat, so that it doesn’t cool off as quickly.
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To replace their feathers on a regular basis (to remove damaged or correct for lost feathers), birds undergo a process called moulting. Depending upon the species, this can happen all at once, be staggered over the course of a year, or happen gradually over several years. Many species undergo moulting during breeding season, to show off their flashy plumage.
Moulting is regulated by the pineal gland and circadian rhythms in most birds, though in pet birds, a somewhat-constant slow moult (punctuated by one or two “big moults” a year) is found, as a result of artificial lighting.
Nouveau Larousse Illustre. Claude Auge, 1898.
Silvery Cheeked Hornbill - Bycanistes brevis
This handsome fellow is a “crested hornbill” or more commonly, a silvery cheeked hornbill. He’s known throughout the evergreen forests of East Africa, and is a flocking bird. Unlike many hornbill species, these birds may roost in flocks of up to several hundred individuals.
Louis Agassiz Fuertes’ Album of Abyssinian Birds and Mammals. Field Museum of Chicago, 1930.
Crested Serpent Eagle - Haematornis undulatus (now Spilornis cheela)
The crested serpent eagle is a medium-sized bird of prey from the tropical regions of Asia. Its genus, Spilornis, is a member of the Circaetinae subfamily, which comprises all of the snake-eagles. As their name suggests, these birds subsist mostly upon snakes and reptiles, and as such most of them live in warmer climates, where serpents are plentiful.
A Century of Birds from the Himalaya Mountains. John Gould (illustration Elizabeth Gould), 1831.
Plate XXXI. The development of a bird. _Le monde de la mer_ 1866
Skulls and Skeleton of Cassowary
There are three extant species of cassowary. Cassowary are the second heaviest living bird, after the ostrich. The largest cassowary (Southern Cassowary - Casuarius casuarius) are also the third tallest, after the ostrich and emu. Like the ostrich and emu, the cassowary are all incapable of flight.
Cassowary live within the humid tropics of New Guinea and Northern Australia, and the function of their fancy head-adornment (casque) may be a response to the pervasive heat in that region. Since it’s not a terribly sturdy structure, and given that it’s heavily vascularized, it may be used for heat dispersion. Given the lack of reports by credible biologists of cassowary coming to blows with their casques, it’s probable that the fancy heads play very little role in mating or mate selection.
These birds are generally herbivorous. They are opportunistically omnivorous, if fungi, small mammals, or insects happen upon them, but are not generally meat-eaters. However, that does not mean that they will not defend themselves against attackers. In 1926, a cassowary being attacked by a pair of young teens with clubs ended up killing the 13-year-old after knocking it down and slashing his jugular with its sharp claws.
Die vergleichende Osteologie. C. H. Pander & Ed. d’Alton, 1821.
Spectacled Owl - Pulsatrix perspicillata
This handsome owl is one of the largest birds of prey in Central and South America. They inhabit dense rainforests where food is plentiful, and like most owls, are almost entirely nocturnal.
While some of its relatives are very picky eaters, spectacled owls will eat almost anything that moves and is (generally) smaller than itself. It has, however, been known to kill large local skunks and other birds of prey, as well.
Currently, they are not considered endangered, but are also not an easy species to find; their large ranges and territoriality make them particularly sparsely populated, even in the densest rainforests. While limited hunting by some indigenous people occurs, deforestation is by far their largest threat.
Histoire naturelle des oiseaux d'Afrique. François Le Vaillant, 1798. [Included in African atlas as an accidental vagrant]
Mandarin Duck - Aix galericulata
The Mandarin duck (generally known simply as “Mandarins”) are one of the two members of the genus Aix. The other member is the North American wood duck. Both are generally monogamous species, and have marked sexual dimorphism - that is, the genders have significantly different features.
In birds, sexual dimorphism generally manifests in males being much more “showy” and flamboyant. A male who can survive while being flashy and attractive must be fit, right?
Reptiles, fish, and insects frequently show another sort of sexual dimorphism, where the female is much larger than the male. Notably the anaconda, anglerfish, and black widow females both outsize their mates by factors of ten, at least. Those females also often ingest or otherwise consume (in the case of the anglerfish) the males after copulation. Both their larger size and the ingestion of the male allow the female of those species to more successfully produce offspring.
Wild Life of the World, Volume II. Richard Lydekker, 1916.
It’s true: The Canada Goose (Branta canadensis) was believed to be either functionally or fully extinct in the wild, and multiple subspecies were believed to be extinct altogether, back in the mid-1900s.
Roseate Spoonbill. The birds of South America. 1915.
