Art Shapiro's Butterfly Site

UPDATE: May 1, 2009

The northward migration finally seems to have ended in the past week, albeit with a minor reversed direction again at the very end. So few animals were in migratory mode by then that one cannot confidently separate the phenomenon from directional randomness. Dozens of very battered animals are still hanging around, nectaring and laying eggs, and larvae are becoming easy to find, especially on thistles.

This morning, May 1, as I walked in to work at 0740, I disturbed a Painted Lady that had apparently spent the night on the sidewalk in College Park, Davis. It was very large, brightly colored, and obviously very fresh and it flew off to the NNW. The direction may or may not be significant, but its presence is: it presumably enclosed yesterday and is the herald of the locally-bred next wave. From now until early June we are likely to see batches of these large, bright PLs eclose, feed for a few days, and depart for the north. Unlike the desert-born ones, they do have to feed. Historically this generation has swarmed the flowers of Linden (Tilia), shrubs of the Rosaceous genus Cotoneaster, and Pride-of-Madeira (Echium fastuosum). The very long migration period in March-April augurs unsynchronized emergences for the next several weeks. Records, observations and pictures are welcome!

UPDATE: April 20, 2009

Painted Ladies continued to migrate through the Central Valley at relatively low and inconspicuous densities, with day-to-day variations in numbers. On the afternoon of April 12 a concerted reverse flow began toward the SSW at Davis and toward the W near Dixon. This became nearly a due N>S flow for the next 3 days, though at all times a few individuals were seen moving in the normal SE>NW direction. Such reversed flows have occurred for a few days in prior migrations, and are not understood. (They are cited in my book on p. 196.) On April 14 a severe cold N-wind event in the Central Valley limited butterfly activity. From the 15th through the 17th directionality became confused and at times nearly random. From the 18th forward the flow was almost entirely SE>NW again, with many individuals dropping out to feed and reproduce and wing condition becoming very worn. There were a few scattered reports of S-ward movement near the coast, but not on any large scale as was true inland. On April 18 Ron Jurek reported two separate flows at Auburn, Placer County (1200’), one from the S>N/NNW and another from the E>W/WNW simultaneously, suggesting that these had been funneled by the topography. This could be purely local, or it could reflect two major streams with different orientations—wish we had more records like this! Numbers near the coast remained generally low, with occasional brief surges. Two Sierran trips – most recently April 19 --revealed a steady but thin continuing movement toward the NW, very sparse at the highest elevations. Intermittent surges continued to be observed at Reno, with one report from the Sweetwater Mountains. One newly-emerged individual was observed last week in the Sacramento area, presumably from an early-season reproductive event. As of this writing (3 PM, April 20) individuals are moving through the UCD campus at a rate of 1 every 3-4 minutes in my visual field, with at least 90% of them going N to NW and most of the rest going S to SW, with one individual seen headed due E. All of these are seemingly in migratory mode and not stopping to nectar or oviposit. How long can they keep coming?! Your observations continue to be welcome.

Thanks for all of your email! It has been a real collaborative effort to track the 2009 Painted Lady migration, as they travel northward. This page features some of the email we have received over the past two weeks, which has helped us track the migration northward. Except for the video, we chose to keep these email anonymous, and have only included the sender's initials. As we receive more email, we will add them to this page for everyone's benefit. If you'd like to send us an update, please use our contact form to submit your message.

April 20, 2009

The PLs coming past the house were heading NW:

Time (no.)
12:30-12:40, 10 min. (8)
15:10-15:20. 10 min. (4)
15:56-16:06, 10 min. (4) -- RJ

April 19, 2009

We saw numerous Painted Ladies at Alpine Meadows on April 12 & 13 - mostly at the summit. I can send pic if you like. -- SM

April 18, 2009

Numbers continue downward:

Time (no.)
11:02-11:03, 1 min. (0)
11:31-11:34, 3 min. (0)
13:17-13:27, 10 min. (3)

These flew west or northwest. Wind from NW

I realized this afternoon that migrants just east of our house were flying from the south and heading north or NNW, while those passing south of the house (the ones I've been counting) were coming from the east and heading west or WNW. Most from each direction maintained their courses, crossing perpendicularly about 100 feet ESE of here, but one from the south took a sharp west turn, and several from the east angled to the NNW or NW. Those from the south probably came out of the canyon near the confluence, and those from the east undoubtedly came up the nearby steep draw running ENE to WSW out of the North Fork. -- RJ

April 17, 2009

I made these counts of PLs flying past the house:

Time (no.)
13:33-13:43, 10 min. (7)
16:05-16:13, 8 min. (4)

About equal numbers flew to the west and to the WNW. From casual observations of a more open area in an adjacent field, I saw two fly across it to the west and one to the NNW. Gusty winds from the west. -- RJ

Phenology has interested me for going on half a century. I began keeping phenological records of butterflies as a teenager in Philadelphia. As an undergraduate at the University of Pennsylvania I took a community ecology course from Jack McCormick, who was under contract to do an ecological study of the Tinicum wetlands (near Philadelphia International Airport). I had been doing an informal faunistic study of the place, purely for the fun of it, and had tons of data. A summary of this work was ultimately incorporated into Jack’s report. The study had a significant phenological component. Harry K. Clench, a butterfly taxonomist at the Carnegie Museum in Pittsburgh and one of the founding members of the Lepidopterists’ Society, published a phenological study of the butterflies of the Powdermill Nature Reserve in southwestern Pennsylvania, and sent me a copy. As I recall, we had already corresponded about the occurrence of unusual Hairstreaks (Lycaenidae) in southeastern Pennsylvania, a subject on which I had published field notes at a tender age. Thus began a correspondence on phenology which continued until Harry’s sudden death. Harry was “into” curve fitting. He had a sine function that worked pretty well for Powdermill, but not for Philadelphia. I was very leery of the approach: prediction was useful, but not nearly so useful as a method that cast light on the underlying mechanisms. The parameters in Harry’s equations were not obviously biologically meaningful.

Authors:  Arthur M. Shapiro and Tim Manolis
Publisher:  University of California Press

Description
The California Tortoiseshell, West Coast Lady, Red Admiral, and Golden Oak Hairstreak are just a few of the many butterfly species found in the floristically rich San Francisco Bay and Sacramento Valley regions. This guide, written for both beginning and experienced butterfly watchers by one of the nation's best-known professional lepidopterists, provides thorough, up-to-date information on all of the butterfly species found in this diverse and accessible region. Written in lively prose, it discusses the natural history and conservation status for these butterflies and at the same time provides an integrated view of butterfly biology based on studies conducted in northern California and around the world. Compact enough for use in the field, the guide also includes tips on butterfly watching, photography, gardening, and more.

• Discusses and identifies more than 130 species
• Species accounts include information on identifying butterflies through behavior, markings, and host plants
• Beautiful full-color plates illustrate top and bottom views of wings for easier identification
• Includes a species checklist and a glossary

Buy this book online
To purchase the book or see more details from the UC Press website, visit the following link. UC Press Bookpage