Did you know there are several species of rare butterflies that make their home in your town?

Local residents can learn all about butterflies, birds of prey, and a plethora of other wildlife and local trail information on Saturday, June 7, because trails groups from Andover and North Andover have organized a jam-packed day of activities in celebration of the 16th National Trails Day.

Events will be held at the Ward Reservation, a 695-acre conservation property with 13 miles of trails in both North Andover and Andover. Ward is always free and open to the public, maintained year-round by the Trustees of Reservations.

The reservation has the highest point in Essex County, the 420-foot Holt Hill, and from the top of it one can see the Boston skyline.

This is the second year the Andover and North Andover trail committees and the Trustees of Reservations have planned National Trails Day events locally.

The day promises fun for families and outdoor enthusiasts alike, said Lisa Swarbrick, event chairwoman from the Friends of North Andover Trails group. Events include guided hikes, a group mountain bike ride, Bay Circuit Trail hike, letterboxing and orienteering workshops, butterfly and birds of prey presentations, kids activities, crafts, and raffles.

"It's definitely a family-oriented event. Our main goal is to educate the public on the many activities that are available in your local area, along with becoming aware of different things that you might not know about, like the solstice stones (on top of Holt Hill), the Bay Circuit Trail and rare butterflies that live in the area. It's more than just hiking, it's enjoying nature, and that's for everybody. It's inspiring, and you get an appreciation of nature," Swarbrick said. "Come this summer, more folks will be staying home due to gas prices. This introduces them to things people can do close to home."

There is a wealth of trails and green spaces in the Andover/North Andover area that many people don't know about, she said. Swarbrick had been using the Friends of North Andover trails for years when she discovered a new trail around Lake Cochichewick during a cleanup day recently.

At trails day on June 7, organizers will have tables set up with maps and information about local green spaces and trails.

"Last year, we got such a positive response (to trails day), it was so encouraging. Many local residents didn't know there were these trails, right in town, that they can go to," Swarbrick said. "We had one person remark, 'Wow, we don't have to drive to New Hampshire to go hiking.'"

Most of the day's events will be held at the top of Holt Hill, which might be cumbersome for folks with limited mobility, Swarbrick noted. All trails day events are free. There is a $1 fee at the orienteering workshop for a map and a $5 materials fee for the letterboxing workshop.

Refreshments will be served at trails day, and raffles for door prizes will be held. Limited parking is available at the reservation, and folks can park along the street on Prospect Road.

Get outside for National Trails Day

r What: Day of activities in celebration of National Trails Day, organized by the Andover and North Andover trail committees and the Trustees of Reservations.

r When: Saturday, June 7, 9 a.m. to 3 p.m.

r Where: Events will be held rain or shine at Ward Reservation, Prospect Road, on the Andover and North Andover town lines.

r More information: For a complete list of events, visit www.andovertrails.org or www.northandovertrails.org. For more information, e-mail Lisa Swarbrick at LS329@comcast.net.

Events include

r Birds of prey presentation by Jack Holt of North Andover, ongoing from 10 a.m. to 3 p.m. He'll discuss the importance of banding birds of prey, with demonstrations of traps and techniques for their use. By monitoring the raptor population, we have a better understanding of the health of our overall environment. He will also have many photos of his banding work to share.

Holt has been banding bald and golden eagles, hawks, owls and other raptors for more than 50 years throughout the United States and Canada. His work has been recorded in "National Geographic" and other nature magazines.

r Poetic nature walks with Karen M. Kline of North Andover, a published poet and frequent writing workshop leader, at 10 a.m. and 1 p.m. Kline has been a board member of the Robert Frost Foundation since 2002.

Walkers will read works of New England poets past and present, and discuss how and why we write. "Inspiration is everywhere in nature once we know how to recognize it," Kline said.

r Nature walk through Pine Hole Bog, hosted by Chris Bowe at 10 a.m. Learn what lives and grows in Pine Hole Bog, a rare quaking bog that features concentric rings of distinct vegetation, each characterized by different growing conditions. The bog, located at the base of Holt Hill, has a nature trail and 700-foot boardwalk.

r Group mountain bike ride, 10 to 11:30 a.m., for experienced adults only.

r Letterboxing workshop with Evy Greene of North Andover, ongoing from 10 a.m. to 3 p.m. Letterboxing involves searching for a weather-proof box hidden by other hikers, using clues and directions found online. Each letterbox has a journal inside, in which folks who have found the box leave a message and a rubber stamp. There is also a different rubber stamp in each box that letterbox seekers stamp in their own journal.

Letterboxes have been hidden all over this country and others. Clues to find the boxes range from simple to complicated, sometimes written in riddles.

r Two-hour guided hikes of the Bay Circuit Trail, a 150-mile trail and greenbelt that links parks and open spaces from Plum Island to Duxbury, at 10 a.m. and noon. A small section of the trail runs through the Andovers and Ward Reservation.

r Butterfly presentation and walk led by expert Howard Hoople, 12:30 to 2 p.m. Hoople will offer a slide show and guide a walk, explaining the rare butterflies that live in the area, showing where they can be found.

r Orienteering presentations, led by James Skelton, first for kids (11 a.m.), second for adults (1 p.m.). Skelton, an expert from New England Orienteering, will explain the art of reading maps and finding your destination using a compass.

r Presentation on solstice stones by John Kimball, 10:30 a.m. and 1:30 p.m. Kimball will talk about the mysterious solstice stones placed on top of Holt Hill by ancient people. The big, rectangular stones form a compass-like sundial formation.

r Refreshments available; crafts and games for kids ongoing throughout the day.