Gabriela, Pony Girls series, by Lisa Mullarkey, published by Calico (an imprint of Magic Wagon, a division of ABDO), 2015.

About the book:

Carly, Daniela, Gabriela, and Kianna – the Pony Girls are ready for their first summer at Storm Cliff Stables! In these four books, each girl has the chance to narrate her own story. Their unique personalities come through as they navigate being away from home, making friends, and caring for the horses at camp. Readers new to chapter books will love this entry into the world of Storm Cliff Stables, with larger text, fewer words, and younger girls in the same wonderful setting!

If she’s not riding a horse, Gabriela is reading a book. She has so many, she even starts a lending library at camp! But after she reads a book about Bigfoot, the Pony Girls start seeing signs of the giant creature around camp. Can they set aside their fears and solve the mystery of whether Bigfoot is real?