Spearrowhawk

The ice age and its subsequent end saw the extinction of a majority of Serinan animal life, leaving many niches vacated. With the hothouse now in full swing, most gaps have since been filled by new lineages. 

The predatory bonebower birds have thrived in this new world in the absence of former competitors and predators, growing larger and filling a mesopredatory role. They haven't lost any of their ferocity with this change, nor their clever use of tools to subdue their prey, meaning they are now even more formidable hunters. Raptorial bonebower descendants such as the 20 inch tall spearrowhawk of the spire forest, in the absence of their once-abundant cactaiga thorns, now chisel spears from tree branches with their sharp beaks and grasping talons, and use them to stab their victims as they hide in holes and cracks in the cementrees. 

Spearrowhawks are wicked smart and make deadly hunters. They most often work in pairs, exploiting the tendency of most spire forest molodonts to have tunnels in the trees with at least two exits, at the top and bottom of a spire. One hunter pokes into one hole, while its mate waits poised at the other as the target is startled and flees into its ambush. Spears are versatile tools, though, and these birds use them to collect all manner of meals - sometimes so efficiently that their prey cannot keep up. Cavity-nesting birds in the range of this predator are now being decimated by a hunter which can reach into holes far too small for it otherwise, and which skewers nestlings one by one, pulling them through the crevice and into its beak as if on a kebob. This brings wide-reaching behavioral changes as such prey species, if they are to survive, are pushed toward alternative nesting behaviors; many abandon cavities and choose nest sites where they cannot be so easily ambushed. They also become more gregarious and cooperate to fend off enemies from these nests, forming larger nesting colonies. 

Male spearrowhawks have moved away from true bower behavior, but still seek to win female affection with food offerings neatly presented on a stick. Females can thus be very choosy during courtship, taking weeks or even months to truly settle down. In this way, she can string along perhaps half a dozen eager mates, all of whom deliver her tidbits of food, so that she may not have to hunt for a single bite herself. This is obviously to her benefit, but it will also ultimately benefit her young. When she finally accepts one of the males as her partner and they move on to nest - ironically, also in a spire forest tree hole - a female who has been fed by many mates will lay larger egg clutches than one who has not, and will have a higher body weight, meaning she will have an easier time later feeding her chicks without losing too much of her own weigh during this strenuous, months-long process. Spearrowhawks have few predators of their own, with their worst enemy being rival pairs of their own species who may go to war over ideal nesting territory. For this reason, incubating females arm themselves so they can quickly strike at would-be nest invaders, and they lay out their nest entrances with a tangle of spiked sticks making entry nearly impossible. This means, however, that the female herself cannot leave the nest cavity either, at least until her chicks are a little older, and so she relies on the male to bring her food as she guards the day and night until they are hatched and then even longer until they are almost a month old. Then, finally, the female and the male both slowly dismantle the defenses and the female at last can stretch her wings. The whole family then move on shortly after and, now that the chicks can do so, will perch on tree branches from then on, where they are far less at risk from attack by their rivals.