When all the parking spaces at the Milwaukee County Parks building were full up, people started parking on the peripheries. And when they filled up, they started parking along the drive, until it was full, too.

So, you'd have to call it a capacity crowd Friday night for the Friends of the Monarch Trail's Blue Moon Party.

Kicking off at 5:30 p.m., there was kite-flying and face-painting for kids, and an education on migration for them and adults.

Barb Agnew, the founder of the trail and leader of the Friends group, brought along a big hanging net bag filled with a variety of butterflies that she raises in her floral shop, Barb and Dick's Wildflower, 12326 Watertown Plank Rd.

Among them were, of course, monarchs, the big orange and black beauties that are probably the most recognized and appreciated butterflies in North America.

Pointing up the need for protection for the species despite its popularity, Agnew demonstrated the application of tracking tags to the wings of some of the monarchs she released onto the County Grounds, ready to start their migratory journey to Central Mexico.

The wing tags – tiny circles of adhesive-backed white film, each with a unique number – are provided and tracked by Monarch Watch at the University of Kansas, the leading monarch research program in the nation. Recovery of tagged butterflies in Mexico provides valuable data on monarch navigation and survival.

Fighting to save a phenomenon

Saying goodbye to the fluttering brood, the crowd embarked on a tour of the Monarch Trail, which winds from the Parks building north around the Eschweiler Buildings.

Along the way, Agnew and other volunteer trail guides – the group was far too large for her to be heard by all – explained how the trail and its most important features will be preserved during and after the construction of three major developments on the Grounds.

Agnew has worked with the Wisconsin Department of Transportation to guarantee access along its Highway 45 easement in the course of the Zoo Interchange reconstruction project, slated to begin in the Plank Road/Swan Boulevard area next year.

She also lobbied Milwaukee County to place a conservancy restriction in the deed to an 89-acre tract adjoining the DOT easement to preserve 11 acres surrounding the Eschweilers as a Habitat Zone.

The whole tract was purchased by UWM for its Innovation Park development, and the Eschweiler campus – part of that investment – has in turn been put up for sale by the UWM Real Estate Foundation for private development.

The current proposal, by residential developer Mandel Group, calls for demolishing four of the five Eschweiler Buildings, three of them designated as historic structures, and would surround the remaining building with new construction for 192 apartments.

As the tour groups reached the Eschweilers, they learned the principal reason for Agnew's efforts in the face of all that development.

Flanking the Eschweiler Buildings on east and west are two groves, where each fall flotillas of monarchs stop to roost in clusters on the trees. It's only one of only four such annual roosting sites known in eastern Wisconsin, according to scientists at the Milwaukee Public Museum.

Protecting that phenomenon of nature has become a passion and an obsession for Agnew and others who have joined her cause.

After the lesson, it was back to partying, with an accordian rendition of "Blue Moon" and polka-ing while moonrise loomed. The expression "once in a blue moon" refers to the rarity of two full moons occuring in the same calendar month.

The date was a happy coincidence. The last week of August is recognized by Monarch Watch as the beginning of the monarch migration season.