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Ancestor: Digit Sparrow

Size: Smallest species: 25 cm  (32 cm wingspan), Largest species: 42 cm  (56 cm wingspan)

Dietary Needs: They have a varied diet in order to survive environments that are sparse on food and to take advantage of seasonal energy rich sources like fruit. Certain invertebrates are eaten, particularly annelid worms and insect larvae. Some seeds also make up part of their diet which are split open by the beak and gizzard stones help break up. Despite this small amount of seed-eating, their granivorous ancestry has given way meat-eating and predatory habits. Some members of the genus are more predatory than others. Some like the broad-winged Passaltivolus cristatus of West Catland rely greatly on carcasses, while the widespread Passaltivolus vulgaris are more likely to acquire meat from the hunting of smaller animals such as mice, lizards, small birds and the eggs and nestlings, but will still feed on carcasses when the chance arises. They eat small animals by holding the dead prey under one of it's feet and tearing discrete bite-size pieces. Sometimes they need to eat fast to avoid food theft or becoming prey itself and so will try to swallow down larger chunks of their prey to make the feeding session quick.

They are amongst the animals that can pick scraps clean off bones when larger animals have eaten everything worthwhile to them. Their sharp, slightly hooked beaks make for a fine effort. For this reason they tend to examine and investigate bones that they find, as there's a possibility it was dragged from a carcass by a larger carnivore recently enough for thin scraps of edible meat to remain. While birds are not renowned for their sense of smell, this bird is particularly sensitive and attracted to the various scents of meat decay, even from great distances.

They can produce a more acidic gastric solution to digest their food and also to sterilize it of the many possible parasites and microbes within the meat. It is not however acidic enough to digest bone, and any accidentally consumed bone (and claws, fur and feathers) is usually passed intact or vomited as a dry lump after the digestible material has been extracted.

Life Cycle: There is little sexual dimorphism, except that females are slightly larger and heavier, and generally dominant. Their ancestor, the digit sparrow, already had low difference between the sexes.

In the mating season (when rain is due) different flocks meet in treetops and tree stands (and rarely, forest) and sometimes mix members as new pairs form between young and unpaired adults. Pair bonds are fairly strong but the bonds of ill-suiting pairs can break down during mating season and pair swapping can occur. Paired adults then go off and search for nesting sites. 

Nests are built in trees out of twigs, grass, moss and any other structural components and lining that seems useful. They are adaptable nesters, able to use whatever is available when their favourite or most useful materials aren't available. They also don't always nest in trees, again it is whatever the environment provides that is high and inaccessible to ground animals. That can be trees, but in places with few to no trees it can also be cliff face ledges and caves, or solitary rock towers in highly eroded landscapes.

Pair bonds are strongest when there are chicks so that they don't eliminate their own offspring. Their feeding demands are high and they need both parents, especially before they have all of their feathers to protect their skin from the world. During this time they need one parent to sit and keep the chicks from losing all of their body heat at night and prevent them from cooking alive during the day, the other to go out and hunt. Parents alternate with these tasks. The food given to very young chicks is pre-digested by the parents, but as they get older they start bringing small animals to the nest whole to pick apart and teach the chicks to do so by example.

Alti juveniles don't start eating things like seeds until their digestive system is more developed. They learn this through mimicking their parents, who they stick with until the next breeding season that they are mature for. They start scratching and pecking stones only first to fill their gizzard, then they move on to seeds. Most altis don't eat very many seeds and don't eat them often, but the behaviour breaks out every so often to help supplement their diet in lean times. They are quite selective about seeds, avoiding the seeds of grass, and poisonous or indigestible seeds of particular shapes and colours.

They will eat certain easily digestible fruits at any age past the regurgitation feeding stage.

Other: A derived sparrow that can use thermals to reach lofty heights. They have excellent semi-binocular vision with clear sight at great distances so that they can see what they are hovering over, but also good peripheral vision because they are themselves prey to larger vertebrates. This good long-range vision and a combination of a harsh environment that kills animals during extremes of heat means that they can often find carcasses, sometimes before other animals do.

They have a whistling, warbling long-range call. Generally they are less vocal at close range and their voice doesn't go below a certain volume. Their vocal range in terms of quietness (below around 60 dB) has been traded for a throat that is able to swallow down more food in one go, so that they can eat more competitively against other scavengers for the same carcass. If they need to vocalise at close range (usually only when trying to be assertive) a loud vocalisation does the job.

They are somewhat social, maintaining familial bonds and flying as small flocks of typically around 5. Around carcasses more of them may converge, with mixed results. Some are possessive and squabble with the other flock. Other times there may be a larger predator or scavenger present, in which case intimidation using numbers sometimes works.

Species:

There are many species across Catland and the Southern hemisphere islands. Two of them are described here:

• Passaltivolus cistratus - The above illustrated species. Very carnivorous species that relies heavily on the natural death of other animals for sustenance. They live in West and Central Catland in open and dry habitats.