by Elizabeth A. Clark, Regan E. Andreola and Stacy H. Minihane
The International Union for Conservation of Nature (IUCN) has placed the monarch butterfly on its Red List of Threatened Species due to sizable population declines observed over the past two decades. Similarly, the U.S. Fish and Wildlife Service (USFWS) has determined that this iconic butterfly warrants listing under the Endangered Species Act, but that the agency is currently precluded from doing so due to other higher priority listing actions. Therefore, the butterfly is considered a candidate species whose status will be reviewed each year until a proposal to list it can be developed. Loss of breeding and overwintering habitat, widespread pesticide use, and effects of climate change have contributed to the population decrease of the monarch butterfly, estimated at a staggering 20-90%.
What Can We as Designers Do?
The addition of this flagship species to the Red List and identifying it as a candidate species by USFWS prompted us to reflect on how our designs can be enhanced to incorporate pollinator habitats while achieving targeted project goals. The USFWS notes that even small actions can build positive momentum for a rebound of monarch populations and benefit other pollinator species. The monarch population that resides in the Eastern U.S. overwinters in Mexico, migrating over great distances crossing swaths of unsuitable habitat such as urban and industrial areas, or fields of mono-culture crops. Creating more green space or corridors of green chains provides refuge, food, and breeding grounds for the butterfly. Incorporating pollinator gardens into land development and redevelopment projects can preserve or even create habitat, increasing foraging opportunities and providing stop-over areas along the lengthy migration.
Monarch butterfly
Both the USFWS and IUCN have acknowledged that transportation and utility projects can play an important part in restoring habitat. With a fairly low investment, these projects can create connected swaths of habitat while achieving their overarching service goals. Solar fields, rail trail projects, and park projects, for example, can also incorporate habitat creation as a best practice. Developments of all types and locations are challenged with balancing the project goals, and the needs of site users and the public, with habitat considerations in what is oftentimes a highly programed environment. However, relatively small efforts can make a big difference to pollinators. For example, in the urban environment rain gardens, detention basin side slopes, as well as dedicated landscaped areas or even seasonal planters present opportunities to create pollinator habitats.
The monarch relies upon milkweed, where it lays eggs and larva feed on until metamorphosis. As adult butterflies, the monarch feeds upon the nectar from a variety of flowering plants throughout the growing season from spring to fall. If conditions are favorable, pollinator gardens should include milkweed and a variety of native flowering plants with different bloom times to support both the breeding and feeding of the butterfly. A thoughtfully designed pollinator garden can provide benefits not only to the monarch but also various species of native bees which are in decline in Massachusetts.
Maintenance
Monarch chrysalis
It’s important to note that the work doesn’t end at designing and installing pollinator habitat areas. Approaches to maintenance have a large impact on success. For example, meadows should not be mowed until all the plants, including late-blooming species, go to seed. Additionally, annual mowing should be undertaken in a phased approach, such that the entire habitat area is never mowed in its entirety in any given year. These methods ensure not only continued seed production, but also reduce impacts on stem-nesting pollinators.
The Municipal Role
Amendments to municipal zoning, subdivision, site plan review, or special permit regulations could be made to require percentages of open space be dedicated to pollinator habitats and, where appropriate, include native milkweed. Municipalities can lead by example by requiring the use of native plantings in their own projects and on municipal land. The City of Somerville has committed to do this with a first of its kind Native Plant Ordinance, and the town of Kingston Conservation Department staff recently developed a seed mix containing plants native to southeastern Massachusetts specifically.
Other Design Considerations
Monarch caterpillar
Reducing impervious area provides many benefits including lessening heat island effects, decreasing volumes of stormwater runoff, increasing natural groundwater recharge, and providing an opportunity for open space preservation and habitat creation. Through the Municipal Separate Storm Sewer System (MS4) program the Environmental Protection Agency is requiring jurisdictional communities in Massachusetts to evaluate their regulations related to required impervious area to promote efficiency. Normalizing practices such as demand based and/or shared parking, implementing reduced parking ratios, and incorporating sustainability considerations into parking, like Shrewsbury is currently doing, can contribute to habitat goals.
Where Do We Go From Here?
Changing the status quo and normalizing the practice of incorporating pollinator habitats into land development projects can start with conversations with development teams. Educating team members and clients about the decline of the species, and outlining opportunities their specific projects may present, is one way designers can help the monarch and other pollinators. Enabling the built environment to knit together a series of stopovers, breeding areas, and food for pollinators is one strategy in a suite of efforts that may help this species rebound.
Elizabeth A. Clark, PE, ENV SP, SITES AP is associate; Regan E. Andreola, RLA, LEED AP, SITES AP is associate; and Stacy H. Minihane, PWS is senior associate at Beals and Thomas, Inc.
