Last Visit to Tilden Regional Park

We went to Tilden Regional Park in Berkeley, California for one last time before leaving.

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It has been a while since we stepped foot into Tilden, but we decided to go today because we only have a few days left. At this time of year, there aren't really any swallowtails around of any species in flight but to our surprise, we did still find a few pipevine swallowtail (Battus philenor hirsuta) caterpillars on the pipevine (Aristolochia californica) growing at the Nature Area's butterfly garden. Last year, they were basically completely gone by this time. It seems that only a few of them ever emerge to make the flight in August; the overwhelming majority of the larvae we reared in the Spring went into diapause. Admittedly, the pipevine at the garden was in very good condition with lots of new growth, perhaps after suffering from disease in the Spring that got it off to a late start, unlike the stuff at Albany Hill which also started growing earlier and got larvae earlier. 

After the garden, we went down a trail. There is a lake there, so a lot of the grass was still somewhat green and there is willow (Salix) and stinging nettle (Urtica dioca). Though not nearly as common as they were a few months ago here, we did across a western tiger swallowtail (Papilio rutulus) still flying this late into the season. We also found a satyr comma (Polygonia satyrus), but there was nothing on the nettles on the trail or at the garden (and strangely, no red admirals [Vanessa atalanta] either). 

After the lake, things get a lot more dry and it starts looking like a typical California landscape -- yellow grass everywhere with tons of tiny prairie butterflies hopping around. There were perhaps hundreds of blue hairstreaks there courting, nectaring, and just going about their business. They were probably all acmon blues (Plebejus acmon). There is also a lot of thistle (Asteraceae) in that particular area with very obvious frass filled silk nests by painted lady (Vanessa cardui) larvae, but we could not actually find any larvae (they must have already pupated).

A little past this segment, there starts to be less grass and more trees consisting mostly of live oaks (Quercus) and a few California buckeyes (Aesculus californica) and pines (Pinus). Here, the dominate species were California ringlets (Coenonympha tullia california) as well as some mylitta and field crescents (Phyciodes mylitta, pulchella) which were courting. There must have been a hundred of all of these too. 

On the way back, we past the lake again. There is a bridge there, but the water underneath it has apparently all dried up. The area is shaded with lots of green trees that we don't know, so no leps. 

After that, we hurried to the Tilden botanical garden which closes at 5 PM. Most of the pipevine there is in atrocious condition, about the same level as the pipevine at Albany Hill, except for the stuff growing right next the water which looked almost as good as Spring. There was nothing flying there whatsoever, but it was still a nice chance to explore some paths that we hadn't walked before. 

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Authors
Brian Liang

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