News

Red Admirals continue to become more abundant in the upper Midwest and southern Ontario, despite several intervening interludes of cold weather. They migrated in on days when warmer, moister air was flowing up from the south. The first of two migration waves occurred on April 15-16, resulting in an abrupt increase in both butterflies and observers noticing them for the first time this year. Locally, I observed Red Admirals flying consistently northward on the 16th, as well as a threefold increase of Red Admirals in territories late that afternoon, as compared with a previous survey a week earlier. After a cooler period, a second and perhaps larger wave arrived in various parts of the Midwest from April 21 -24, again resulting in a further increase in the local population. Observers in Minneapolis, southern Wisconsin, southern Michigan, and southern Ontario reported large increases in Red Admirals, and some substantial northward migrations occurred in southern Ontario, raising the question of whether Red Admirals were actually crossing Lakes Erie and Ontario.

A subsequent period of cooler weather has quieted their activity recently, with far fewer seen during a local survey on April 29th than during a previous one on April 23. Whether this is due to the butterflies sheltering from the cool weather or to an actual decrease in numbers remains to be seen.

-- Royce Bitzer, April 30, 2019

As I was writing here last month, I’ve been following the enormous Painted Lady migration that’s been happening in California and the Southwest since late January to early February.  While this migration continues northward, it’s now also time to turn more attention eastward as wind and weather patterns have become favorable for Red Admirals and American Ladies to migrate northward into the upper Midwest,  the eastern states, and southern Ontario.  Painted Ladies may be arriving in our area somewhat later this spring, perhaps from the west, or perhaps from a smaller population that overwintered in Texas.

Red Admirals have arrived in the upper Midwest, and are already here in Iowa – they seem to have come with the warm southerly wind last Saturday, April 6, resulting in sightings in central Iowa's Story and Boone Counties on that day.  They were also spotted in Omaha, Nebraska on April 2, and in Kansas City, Missouri on April 5.  Chip Taylor, the director of Monarch Watch, spotted his first two in Lawrence, Kansas on April 6th, while suggesting that Red Admirals could have arrived there a few days earlier.  A first-of-the-season Red Admiral was also seen on April 8 in Kingsville, Ontario, near Point Pelee National Park.

Since yesterday, it's likely that any further northward Red Admiral movement will be literally stopped cold (at least temporarily) by an enormous low-pressure system passing through the northern Great Plains, Minnesota, and Wisconsin.  This storm has brought us two days of high winds in central Iowa, and heavy snow in states to our north.  To our south, temperatures were in the 60s F in southern Iowa and in the low 80s in Kansas.  Under these conditions, any additional Red Admirals arriving from farther south might stop migrating and accumulate in these areas, resulting in a sudden increase in the number present.

-- Royce Bitzer, April 11, 2019

The ongoing Painted Lady migration is well underway, after a seeming delay in some areas due to cool weather.  Large numbers were passing through Palm Springs, California on and before March 2, 2019, and some of these butterflies were observed flying westward.  They also became abundant in the Las Vegas area around March 4, and continue to be present there in large numbers.  Most recently, an enormous swarm has been flying northward through the Los Angeles area, both yesterday and today, March 12.  Painted Ladies are now widespread throughout southern California, including in Borrego Springs, where an extensive northward migration was underway on March 11.  In Yuma, in the southwestern corner of Arizona, Painted Ladies have likewise been flying in huge numbers for the last two to three weeks, mainly in a northwestern direction.  The entire outbreak was likely triggered by considerable local rain associated with the current El Niño event, followed by prolific blooms of desert annuals and growth of larval food plants.

Although the butterflies have often been reported as flying generally northward, there seems to be substantial local variation in flight direction in much the same way as occurred during a similar large and well-observed migration from February through April 2005, as you can see by looking at our flight direction map for that interval.  Once there, check the Painted Lady box, enter that range of dates, and zoom in to see the directions of the arrows and get an impression of how the migration proceeded and spread during spring 2005.

-- Royce Bitzer, March 12, 2019

The Red Admiral and Painted Lady Research Site will have a new format, perhaps as soon as tomorrow.  Revisions have been underway for the past several months, and we have been reviewing and editing the changes during the past three weeks.

Among the changes will be a new interactive Google map with more options for viewing observations by a specific range of dates (rather than simply by a range of months as in the map we've had), as well as for viewing all the observations for a particular month or set of months over two or more years.  These changes allow the map to show more specific periods of time during migrations, as well as multi-year seasonal ranges of each species of butterfly.  The new map also offers both roadmap and satellite views, to make both viewing existing points and adding new observations easier, and map points of any color will also show up much more clearly against the new backgrounds.  Clicking any point on the map will now show its geographic coordinates as well as all of the information shown previously.  We have also revised the page for entering new observations.  Besides searching for a location by name or clicking on the map, you will now have a third option to directly enter your latitude and longitude.  Wind directions and butterfly flight directions on the entry form are also defined more clearly than before.

--Royce Bitzer, January 24, 2018