Swallowswarms
When whales fly

The Reliquia forest, located in the northernmost part of the continent, is what remains of the warm plant associations of the Cambiocene epoch. Here you can still find animal species of warm climates, both sedentary and migratory. This ecoregion is known to be the last wintering site of the swallowswarm (Ornithocetus venatorii), a large bird with an even larger mouth. Although it does not seem, it is a distant relative of swallows: like its ancestors, the Swalloswarm nourishes by predating flying insects, which it catches through its mouth. It's a sort of flying whale, which passively hunts by approaching large swarms of insects.
Because of its diet, the swallowswarm prefers areas close to the water and with large vertebrates, where insect aggregations are more frequent. This bird species is not present in the coldvanna and in the tramplesteppe during winter, where low temperatures do not allow continuous insect activity all year round. Only some areas of the Relic Forest, thanks to its mild winters that rarely go below freezing, are still suitable for this species. Once counting over ten thousand, swallowswarms are now a declining species, with no more than 1000 breeding pairs according to the latest census. 

Despite being basically an insect filter feeder, it is not uncommon for swallowswarms to actively hunt vertebrates, such as small birds. As if they were a shoal of fish, the bird flock is attacked by more swallwswarms, causing chaos in the group. At this point, these big predators just have to open their mouths inside the flock to feed on unwary birds. This behavior, however, is less successful and involves a great energy effort for these predators, who exploit this tactic only in winter and migration periods.
Swallowswarms use to rest on the dead tops of trees, where they can boast a greater spatial vision, in order to look for new swarms to prey on. Because of their size and long wings, they are unable to move in densely wooded areas, preferring large floodplains or other open areas maintained by large herbivores.