Home-Earth has an impressive diversity of terrestrial carnivorous flying birds: owls, falcons, hawks, buzzards, eagles, ospreys, and so on. All these predators, with the exception of a few megalomaniac songbirds (Passeriformes), kingfishers (Alcedinidae) and frogmouths (Podargidae), belong to the Falconiformes (diurnal birds of prey) and the Strigiformes (owls), two groups of Neornithes that arose in the Eocene or perhaps Palaeocene. Spec's birds of prey, the avisaurs, are somewhat different.

An avisaur using its distinctive teeth to feed from an animal carcass.

Most immediately noticeable, avisaurs possess of teeth and lack a beak (hooked or otherwise), which gives their heads a surreal dromaeosaur-like appearance. Also, despite many neornithine-like features in their flight apparatus, they belong to the Enantiornithes, that strange group of 'opposite-birds' that arose in the Early Cretaceous with forms like Cuspirostrisornis.


Golden Flanker (Veraquila chrysaetos)


Golden Flanker, Veraquila chrysaetos (Holarctic)

The golden flanker (Veraquila chrysaetos), which is actually rather brown, rules the skies above all open, landscapes of the Holarctic with suitable perches, thus avoiding competition with the chickenhawks (Acioripiter). The young begin with hunting grasshoppers and big beetles, then for a short period they turn to snails, then to Specworld mice, zams, small lizards and snakes, and then, when the first teeth with serrations grow, to djads, dogbunnies and various henchick species. The largest individuals (with a wingspan over 2 m) have been seen to attack juvenile therizinosaurs, although this behavior is rare.

Head of a golden flanker, Veraquila chrysaetos

Papuan Flanker (Veraquila victor)

Papuan flanker

Adult male Papuan flanker, Veraquila victor (Papua New Guinea) 

Papua is a dangerous place for spexplorers and pretty much everything else except adult Papuan flankers (Veraquila victor). Hatching in a nest of 3 to 4 eggs on top of the rainforest, the little anti-eagles (originally described as a wholly separate species, Antifalco minimus) with their small, straight, conical teeth, soon start hunting big beetles and other insects. One-year-olds have similarly small teeth, but lots more of them, so they can easily pluck the feathers and even the fur off their prey. 

Papuan flanker chick, Veraquila victor

At this age, cutting edges appear on the teeth. Around the age of 3 years (and a wingspan of about 2 m), tooth shape and number changes again, and the eagles can now cut meat off killed dendrosaurs by means of strongly recurved, finely serrated teeth that are flattened side to side. Fully adult Papuan flankers sometimes hunt terrestrial prey like piggy-beaks or, in rare cases, even Papuan muppets, which they stab from above through the hip bones into the kidneys with claws like a croctiger's.

Imperial Flanker (Haleuaetus euleucocephalus)

Imperial flanker

Imperial flanker, Haleuaetus euleucocephalus (Western North America)

 The Pacific coast of northern North America is home to the imperial flanker (Haleuaetus euleucocephalus) with its beautiful white head, neck and tail.  However, young individuals could be mistaken for beakless kingfishers. Fish (dead or alive) form the largest part of the diet of this species throughout its life cycle, but an imperial flanker will not refuse other prey of fitting sizes or carrion.

Other species of sea-flankers (Haleuaetus) are distributed pretty much around the world.

Pentagon Chickenhawk ( Acioripiter pentagonus)

Pentagon chickenhawk

Pentagon chickenhawk, Acioripiter pentagonus (Eastern North America)

The pentagon chickenhawk (Acioripiter pentagonus), so called after the vaguely pentagonal white spot on the neck of adult males, is just about the only avisaurid species in the forests of eastern North America. Hatching in a nest of up to 5 eggs, the young stay in the tree crowns and hunt first insects, then nonpoisonous birds like jaubs, pickpeckers and otherworld finches like painted pfiffles, then multis and sometimes not-coons, and when maturity approaches around the age of 4 years (and a wingspan of about 1 m), they start to fly fast very close to the ground, pursuing mainly henchicks, as well as nearcrows, and the occasional djad. Large pentagon chickenhawks have even been reported to attack hellrats. Otherworld doves are never safe, but during the nut-glut, chestnut doves form the main part of the diet of over 2-year-old pentagon chickenhawks.

Adult pentagon chickenhawks are very territorial. And if something comes within 10 m of their nest, they become totally furious. It is not advisable to study their nesting behavior without one of those knife- and bulletproof vests and a good helmet.

Sharp-Winged Riff (Antifalco abramsi)

Sharp-winged riff

Sharp-winged riff, Antifalco abramsi (American grasslands)

Not all avisaurids grow so large, however. The sharp-winged riff (Antifalco abramsi), for example, hardly ever reaches more than 70 cm wingspan. In northern summer, riffs live and breed on the fringes of the prairies of North America, in winter the older individuals migrate to the South American pampas, following much of their prey - small birds that these quick-witted predators catch in mid-air. Even swoops and mistriders are not safe, but the usual prey, especially of young riffs, are jaubs and otherworld finches, followed by the smaller species of nearcrows and otherworld pigeons.

Like all avisaurs, riffs do not care for their chicks past the first few days after their hatching. Unlike other avisaur species, however, in which the adults and young have very little contact, young riffs (those too young to migrate, still lacking cutting edges on the teeth) will sometimes congregate and fly around the adults in sizable swarms. The functions of this "chick-magnet" behavior is unclear, though many researchers hypothesize that the young are feeding off of flying insects flushed up by the adults' hunting. 

Riffs can most often be seen in dawn or dusk, generally alone. They rarely vocalize, and when they do so, their call is a muted, cough-like "ugh".

Pied Snakehawk (Acioripiter mexicanus)

Pied snakehawk

Pied snakehawk, Acioripiter mexicanus (southern North America and Central America)

A southern relative of the pentagon chickenhawk, the pied snakehawk, is common in the skies of southern North America and Central America.

Checked Mig (Acioripitriscus vittatus)

Checked mig

Checked mig, Acioripitriscus vittatus (eastern Asia and Australia)

The checked mig (Acioripitriscus vittatus) is another related species; it is migratory, flying from eastern Asia to Australia each northern autumn and back each southern autumn. It is notable for its white snout and short tail.

Other mig species (Acioripitriscus) occur from southern Europe to northeastern Siberia.

Tiger-Necked Flanker (Veraquila australis)

Tiger-necked flanker

Tiger-necked flanker, Veraquila australis (Australia)

Reaching up to 2 m wingspan, the tiger-necked flanker is the largest of the Australian avisaurs and the ruler of Ozzie woodlands. Adult (5-year-old or so) tiger-neck flankers live mainly off smaller species of brush-runners and hypsies.


Not all avisaurs are daylight predators. The scowls (Allostriginae) have adapted to night-hunting, evolving sensitive night vision, dish-shaped, sound-focusing faces, and silent, silky wings. These birds, have, in essence, taken the place of Home Earth owls.

Spotted Scowl (Odontuto maculata)


Spotted scowl, Odontuto maculata (worldwide)

There are cosmopolitan species of scowls. The spotted scowl (Odontuto maculata), for example, can be found on practically all landmasses except Antarctica and most Pacific islands.

With its 35 cm adult length, the spotted scowl ranks among the smaller scowl species. Juveniles and subadults (up to the age of 2½ years) eat mostly insects and earthworms; with size the amount of small mammals and nonpoisonous birds in the diet increases.

Bob (Pseudobubo atrotugurius)


Bob, Pseudobubo atrotugurius (North America)

With a wingspan of over 150 cm, the bob (Pseudobubo atrotugurius) is one of the largest scowls in the world. Even hellrats and young baskervilles are not safe from the adults, though their most common prey are dogbunnies, pseudorats and multis. Especially 2-year-old bobs participate in the nut-glut by stalking sleeping chestnut doves. Bobs don't refuse carrion either. Living in the forests of North America, the bob is known for its blood-curdling call, which in the correct circumstances can sound like laughter played backwards.

Striped Scowl (Allostrix rowlingae)


Striped scowl, Allostrix rowlingae, with hemming, Xenomarmota sp. (Northern Eurasia)

The striped scowl of northern Eurasia is, from a distance, almost indistinguishable from an owl. On a closer inspection, however, an observer would notice the scowl's un-owl-like feet, and its lack of a beak in favor of a distinctly dinosaurian tooth-filled snout.

Like most avisaurs, striped scowls mate in the winter and lay up to 10 eggs that hatch into precocial young in the spring. These baby scowls soon fly away from their parents' nest and begin to hunt for themselves, progressing through different size-niches as they age, in typical avisaur fashion, until they achieve their adult height of about 60 centimeters after some 4 years. Throughout their lives, striped scowls feed upon a variety of small and medium-sized mammals, and occasionally birds and other small dinosaurs.

Willow Scowl (Allostrix diurna)


Willow scowl, Allostrix diurna (North America)

The willow scowl is a widespread species in temperate North America. Willow scowls are somewhat more diurnal than other scowls, and may often be seen flying through the permanently dark understory of America's old-growth forests.

             ,=†Cuspirostrisornis houi
             | ,=†Neuquenornis volans 
=Avisauridae=| `=Antifalco=Antifalco abramsi (Sharp-winged riff)
             | ,=†Avisaurus
             | |
             `=|=†Soroavisaurus australis 
               |                                ,=P. atrotugurius (Bob)
               |                   ,=Pseudobubo=|
               |                   |            `=P. pseudobubo (Eurasian big-eared scowl)
               |                 ,=|
               |                 | |           ,=A. rowlingae (Striped scowl)
               | ,=Allostriginae=| `=Allostrix=|
               | |               |             `=A. diurna (Willow scowl)
               | |               |
               | |               `=Odontuto maculata (Spotted scowl)
               | |
               `=|               ,=A. mexicanus (Pied snakehawk)
                 | ,=Acioripiter=|
                 | |             `=A. pentagonus (Pentagon chickenhawk)
                   | ,=Haleuaetus euleucocephalus (Imperial flanker)
                     |           ,=V. chrysaetos (Golden flanker)
                                 | ,=V. victor (Papuan flanker)
                                   `=V. australis (Tiger-necked flanker)

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