Pollinator Pilot Project

The monarch butterfly (Danaus plexippus L) requires milkweed species to complete its lifecycle and common milkweed can be found in a variety of landscapes and soil types across New Hampshire. Milkweed is utilized by monarchs as both a host plant for monarchs during their egg and juvenile caterpillar stage and as a nectaring source to feed monarch adults. Common Milkweed provides them with nectar sources important for reproduction and their migration. One of the main threats to this species is the loss of habitat, and the loss of Common Milkweed host plants. 

In 2018, the Rockingham County Conservation District (RCCD) was awarded funding through an agreement between the Natural Resources Conservation Service (NRCS) and the New Hampshire Association of Conservation Districts (NHACD) to test if different mowing regimes increased, decreased or maintained the density of common milkweed stems in an effort to demonstrate practical mowing management practices.

Traditionally, fields and field edges have been important habitat types where common milkweed flourishes, and generally fields have been mowed at varying times for hay production. We hypothesized that early season mowing practices would be an effective way to enhance existing milkweed/pollinator habitat. It was also expected that the results of this demonstration project would allow NRCS to utilize this information to develop a conservation standard for landowners to implement on their fields.

Site walks with Xerces, and NRCS, and partners were completed to determine practices and challenges at each site. On average, sites that were mowed early had a greater number of milkweed stems over the data collection period, except for the Strafford County Farm site. There are many other factors that influenced each site, and each mowing and monitoring practice. It is interesting to note that for two sites, the highest common milkweed mowed counts were in 2019, and lowest (with one glitch) took place in 2022 during a drought summer (Figure 2). It is also interesting to notice that there is an overall decline in common milkweed numbers from 2019 to 2022 at several sites (Figure 2). This is disturbing news, given that the monarch butterfly will likely be a federally endangered species in the near future. We are hopeful that there will be more studies or demonstrations focused on enhancing monarch habitat.

RCCD collaborated with several partners including Strafford County Conservation District (SCCD), The Nature Conservancy of New Hampshire (TNC), The Xerces Society for Invertebrate Conservation (Xerces), NH Fish and Game (NHFG), and the Natural Resources Conservation Service (NRCS) that assisted with the management and conservation practices implemented at each selected site.

Project Site Locations 2018-2022:

  • Great Bog, Portsmouth & Brentwood Wildlife Management Areas(WMA)

  • Saltbox Farm, Stratham NH

  • TNC Lubberland Creek, Newmarket

  • Strafford County Farm, Dover

  • Wagon Hill, Durham

  • Emery Farm, Greenland

On average, sites that were mowed early had a greater number of milkweed stems over the data collection period, except for the Strafford County Farm site.

It is recommended that another demonstration or pilot project be completed that includes additional analysis to see if these methods are statistically significant and test a similar hypothesis over a few of the stable sites during upcoming years and weather patterns. Additional improvements could include soil analysis, timing of mowing, height of mowing, and standardized experimental design (numbers and sizes of plots) to promote statistically stronger data collection. It is now more important than ever to promote extensive common milkweed habitat areas and studies to assist in managing more breeding habitats in our region. Promoting additional conservation practices aimed at contributing to the health and prosperity of the migratory population of monarch butterflies will only benefit the species and should be a major focus for future efforts.