Construction of a new bridge across a creek has made a beautiful and convenient loop hike possible at Round Valley Regional Preserve south of Brentwood.

The option has always been there, but until now it has been an unofficial short cut that required descending into the creek bed and clambering up the other side.

The new connector isn't on the current park maps, but here's how it works:

From the trailhead on Marsh Creek Road, cross the bridge over Marsh Creek and walk, ride or bike into the park on the Miwok Trail.

About a mile-and-a-half in, as the terrain starts to open up into Round Valley, you'll see the Hardy Canyon Trail branching off to the left, and a water tank on the right.

Just past the water tank, bear right between some wooden posts that look like they once supported a gate. At this point you can see the bridge railing about 20 yards ahead and slightly to the left. The gateposts are your landmark; there's no signpost yet.

Cross the bridge, go through a gate on the far side, and turn left along the fence for a short walk to the junction of the Murphy Meadow and Fox Tail Trails. Go left on the Murphy Meadow Trail. The Fox Tail Trail is pretty, but it dead-ends at the park boundary.

From here the map makes the route obvious. The Murphy Meadow Trail leads past the turn to Round Valley Group Camp and back around to the Miwok Trail, on which you can return to the start.

Round Valley is a great park for wildlife. Golden eagles and other raptors feed on the abundant ground squirrel population. I've also seen coyote, deer, rattlesnakes and one lonely tarantula.

Round Valley's trailhead is on Marsh Creek Road between Deer Valley and Camino Diablo roads. Entry and parking are free. No dogs are allowed at Round Valley. The reason is that the park is habitat for the rare and endangered San Joaquin kit fox, and domestic dogs can carry diseases to which the kit fox has no resistance.

FOR KIDS: Naturalists Katie Colbert and Cat Taylor host a series of Outdoor Discovery programs in various regional parks, designed for children ages 3 through 5 accompanied by a parent.

Katie has scheduled a "buckeye babies" program from 10 to 11:30 a.m. Dec. 29 at Sunol Regional Wilderness. The group will plant last year's little buckeye trees and learn about how trees grow from seeds.

Registration is required, and there's a fee of $6 ($8 for nondistrict residents). For details and registration, call 888-327-2757. Select option 2 and refer to program #30698.

PARKS OPEN: During Christmas and New Year's weeks, all the regional parks will be open during daylight hours, though visitor centers are generally closed on Christmas and New Year's days. If the weather's good, a walk or ride in the parks offers a nice break from the seasonal hustle and bustle.

And however you celebrate the season, here's wishing you happy holidays and a great New Year.

Ned MacKay writes a regular column about East Bay Regional Park District sites and activities. Email him at nedmackay@comcast.net.