What Birds Know is an odd read, if you don't know what it is going in. It looks like it's going to be some kind of Fantasy styled comic, but the supernatural bits take a back seat to the trials and tribulations of the three girls and their families, though the supernatural does play an important role in the story.
Most character development is told in flashbacks to various points in the girl's lives, which works very well and fully fleshes out the character ticks that become obvious in the first pages. What is usually first written off as someone being kind of a dick ends up being seated in deeply fostered childhood emotional problems that continue to plague all three girls. Mostly everyone so far has been given a reason behind their various personal flaws, from grumpiness to lack of love for a child, though some are much more sympathetic than others and some are much less sympathetic. Expect to feel great annoyance for some of the family members and a good of pity for the girls and their shoddy childhoods.
The fantasy elements have not been fully flesh out so far and come across as surreal and on the far end of supernatural. It's definitely building towards something, though, and the bizarre nature of the world beyond the tower is the instigator for revealing the truth of the lives of the main characters. It also get's pretty creepy as it goes on, so, you know, watch out for that.
All in all, it's a very engaging read, but be prepared for a good amount of emotional torque and very little in the way of cheery, happy, fun times.