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Moths & Bushtits. Spring at Berkeley's Botanical Gardens

Ceanothus SilkMoth

There's alot going on at Berkeley's Regional Botanical Gardens. Trilliums and wallflowers are blooming and trees are beginning to leaf out. Spring has already begun around here. A week ago, park staff directed me to a stunning ceanothus silk moth (Hyalophora euryalus) who've just came out of its cocoon and was holding on motionless on ...yes, a ceanothus branch. The short antenna immediately gave her away as a female (males have noticeably larger antenna) and the large abdomen was a sure sign she was gravid and filled with eggs. Ceanothus silk moths are active at night and lay motionless during the day. In the early morning hours females release a chemical to attract males.

I visited the gardens again last Friday to join Alan Kaplan's Golden Gate Audubon monthly walk. The silk moth’s cocoon (not the moth) was still there, but this time the highlight was an active Bushtit’s nest.

Bushtit female

During the nest building process each bird takes different roles (see video). The female (notice ligh-colored eye) focuses primarily on the interior while the dark-eyed male is often all about exterior design. The Bushtit’s green architecture focuses on insulation and concealing tiny eggs and nestlings. The sack-like design has a hood to cover the entrance at the top and it’s very effective in controlling the nest’s temperature. A study in Arizona found that the interior of empty bushtit nests remained at 85℉ despite an outside temperature of 111 ℉ !

Male with nesting material

If you are not familiar with the gardens or haven't visited them for a while, I recommend you go. It is a great place to take a walk or bring the kids for an outing. I also recommend you join one of Alan Kaplan’s walks. He is one of the best naturalists I’ve known. His GGAS walks occur on the 1st and 2nd Friday of the month.

Hasta pronto,


#birdwatching #bushtits #spring #botanicalgardens

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