As 2013 draws to a close, Regional Park District naturalists will send it off with a variety of programs showcasing the seasonal attractions of the East Bay's great outdoors.

Ordinarily, the annual gathering of monarch butterflies in the eucalyptus grove at Ardenwood Historic Farm in Fremont is a must-see natural phenomenon. Unfortunately, this year is different. On the day after Thanksgiving, staff counted an estimated 1,000 monarch butterflies in the grove. But after rain and a cold snap, the population dropped to 800 in early December. It was down to 30 by midmonth, and only a few butterflies remained as of late December. Many factors may have contributed to their departure. There are two websites with lots of information about monarch butterfly conservation: www.xerces.org and www.monarchalert.calpoly.edu.

Although there are few butterflies remaining in the grove, you can still see their life cycle in action at Ardenwood's greenhouse, where milkweed plants still host monarch eggs, caterpillars and chrysalides. And butterfly-themed programs continue through December. Guided walks will meet at the granary building at 11 a.m. and 1:30 p.m. on Saturday and Sunday. Also, there will be guided walks from the Granary at 11:30 a.m. and 1:30 p.m. New Year's Day.

Ardenwood is at 34600 Ardenwood Blvd., just north of Highway 84 (the Dumbarton Bridge approach). For details, including entry fees, call 888-327-2757, ext. 2797.


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CRAB COVE: What else is going on at year's end? As mentioned in the previous column, the Holiday Open House at Crab Cove Visitor Center in Alameda is from 10 a.m. to 3:30 p.m. Friday, with lots of family-friendly activities planned. Admission is free. Crab Cove is located at 1252 McKay Ave. off Central Avenue. For information, call 510-544-3187.

GETTING VOLCANIC: Also, on Friday, naturalist "Trail Gail" Broesder will lead a hike from 9 a.m. to 2 p.m. at Sibley Volcanic Regional Preserve in the Oakland Hills. Sibley is known for its volcanic geology and contemporary labyrinths, one rock in height, constructed by mostly anonymous builders. There may be some migrating newts out and about, too.

The free hike is for ages 12 and older. Meet Gail at the Sibley entrance parking lot on Skyline Boulevard a short distance south of the intersection with Grizzly Peak Boulevard. Bring a snack to share. For details, call 510-544-2233.

FOR THE BIRDERS: And for early risers there's a bird walk from 7:30 to 9 a.m. Tuesday at Oyster Bay Regional Shoreline in San Leandro, led by naturalist Francis Mendoza. All levels of birding experience are welcome, and there will be some binoculars available for loan. It's free, and no registration is needed. Just show up at the trailhead at the north end of Neptune Drive. Rain cancels. For information and directions, call 510-544-3187.

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