Muggles' Guide to Harry Potter/Magic/Avis

Overview
The Avis spell causes a flock of birds to appear out of the end of the caster's wand.

Extended Description
This spell is used by Mr. Ollivander as part of the process of testing Krum's wand in the Wand Weighing ceremony. Krum's wand is a very sturdy wand, made of hornbeam and dragon heartstring, thicker than most; the Avis spell causes it to give a report like a gun as it creates a flock of small, twittering birds that fly off through the open window.

In Harry's sixth year, Hermione performs this spell twice: once in Transfiguration class, where she is the only person to be able to do it, unsurprisingly; and once a week later when she is suffering jealousy from Lavender and Ron's budding romance.

Analysis
This is a sixth-year spell; creation of living creatures, unlike Transfiguration from non-living objects, is not taught to Hogwarts students until quite late in their education. As such, it is a decent test of the capabilities of a wand.

Avis in Latin translates directly to "bird".