Things to do Saturday in Northern Colorado: village trick-or-treat, a pumpkin plunge and a library birthday

8-10 a.m. Guided Bird Walk — Volunteer birders lead a walk to spot and identify resident and migratory birds by sight and sound. Willow Bend Natural Area, Loveland.

10-11 a.m. Cereal,Centers, & Stories — Children in grades K-5 can have cereal, hear a story and try art and STEM activities. Fort Lupton Public & School Library - Public Branch; Free.

11 a.m.-2 p.m. Pumpkin Plunge — Participants jump into the pool to find a floating pumpkin; registration is required. Community Recreation Center Indoor Pool - 250 N 11th St. Windsor CO 80550.

noon-3 p.m. Fall Skate Fest @ Lawson Skatepark! — Skate contests, a live band, a food truck and giveaways are part of the skate fest. Estes Park Sports Complex; Free; For kids and families.

1:30-3 p.m. Trimble® SketchUp® Project Spectrum - 3D Modelling Class — Participants learn the basics of SketchUp 3D modeling software, then create projects based on their interests. Carbon Valley Regional Library, Firestone; Free; For kids, teens and adults.

1:30-3:30 p.m. Lions, Coyotes, and Bears, Oh, My! — A program about predators includes photos, videos, skulls and pelts, followed by a walk to watch and listen for wildlife. Bellvue.

2-6 p.m. Howl-O-Ween Trick-or-Treat — Visitors can trick-or-treat through the village and try fall crafts and activities. Centennial Village Museum, Greeley.

4-7 p.m. Downtown Loveland ZombieCrawl — The ZombieCrawl has live music, zombie makeup artists, a costume contest and a crawl through downtown Loveland. Loveland Aleworks,118 West 4th Street, Loveland, CO 80537, USA.

5:30-8 p.m. Old Town Library's 50th Birthday Celebration — The library marks its 50th birthday with a 1970s-themed party, a time capsule opening, refreshments and activity stations. Old Town Library, Fort Collins; Free; For babies, toddlers, preschoolers, kids, teens, families and adults.

7 p.m. An Evening with Celtic Thunder 2026: Celebrate your Favorite Songs — Irish and Scottish vocal group Celtic Thunder performs with its band. Union Colony Civic Center, Greeley.