Sylvia has come to live at her grandmother's farm after having lived eight years in a crowded, dirty, noisy city with her parents. She is afraid of people which indicates that she did not have very good experiences with others in that city, or perhaps that there were just so many of them that she couldn't breathe.
After moving to the farm, she suddenly has a freedom that we can assume she didn't have before. Perhaps one reason she is afraid of people is that her parents repeatedly warned her about wandering around outside of their home alone for all the dangers that faced her outside their door.
Sylvia does not fear roaming alone on the farm. In fact, she never hurries her walks with the cow as she loves wandering the farm's grounds and explores every inch of it. Her companions are the animals--both wild and domestic--and she is in her element.
Her name, Sylvia, comes from the Latin root "sylvan" meaning "wooded area". This gives us some hint as to how natural she feels in the woods, in the country, away from a crowded and busy city.
It also helps us to understand or perhaps even forcast that Sylvia would side with the heron instead of the hunter who attempts to befriend her for the sole purpose of killing her beloved bird.