Data are population size estimates for monarch butterflies overwintering in Mexico as well as 76 potential stressors and 3 correlates. These stressors include disease, pesticide, herbicide, temperature, precipitation, and habitat loss measured for Mexican overwintering area and Southern, North Central, and Northeastern breeding areas.

This release covers the entire study region (Midwest) and includes data used for retrospective population modeling effort as well as climate projection data for each county on the summer breeding grounds for three future time periods (2025-2045, 2060-2080, 2080-2100) under three climate scenarios (RCP 2.6, 4.5, 8.5) of key thermal climate profiles (based on a range of typical thermal thresholds) relevant to butterfly (and other insect growth) including growing degree days and precipitation (Apr through Aug). Values were generated from an ensemble of GCMs.

The long decline of the eastern migratory population of monarch butterflies (Danaus plexippus) appears to have abated in recent years and the population now persists at a much-reduced abundance. Stochastic variation in abundance typical of monarch butterflies, and other insects, places this population at heightened risk of quasi-extinction, a level of abundance below which recovery of the migratory behavior is uncertain. These data and results provide insight into the near-term status and trajectory of the eastern migratory population of monarch butterflies. Within the stationarymonarchdata.csv, overwinter[ha] are annual monarch butterfly overwinter area occupied estimates as provided by World Wildlife Fund-Mexico and breedingcounts are annual indices of Illinois Butterfly Monitoring Network counts of monarch butterflies in summer.

This code describes graphical and analytical comparisons between monarch butterfly survey data collected during summer breeding, fall migration, and winter.

The decline of the iconic monarch butterfly in North America has motivated research on the impacts of land use and land cover (LULC) change and climate variability on monarch habitat and population dynamics. We investigated spring and fall trends in LULC, milkweed and nectar resources over a 20-year period, and ~30 years of climate variables in Mexico and Texas, a key region supporting spring and fall migration during monarchs annual life cycle. We estimated a 2.9% decline in milkweed in Texas, but little to no change in Mexico. Fall and spring nectar resources declined <1% in both countries. Vegetation greenness increased in both the fall and spring in Mexico while the other climate variables, for both countries, did not. Monarch habitat in Mexico and Texas appears relatively more intact than in other parts of their range, particularly the midwestern agricultural landscapes of the US. Given the relatively modest observed changes, it seems unlikely that habitat loss (quantity and quality) in Mexico and Texas has caused large declines in population size or survival during migration.

Stabilizing the eastern, migratory population of monarch butterflies (Danaus plexippus) is expected to require substantial habitat restoration on agricultural land in the core breeding area of the Upper Midwestern U.S. Previous research has considered the potential to utilize marginal land for this purpose because of its low productivity, erodible soils, and high nutrient input requirements. This strategy has strong potential for restoring milkweed (Asclepias spp.), but may be limited in terms of its ability to generate additional biophysical and socioeconomic benefits for local communities. Here we explore the possibility of restoring milkweed via the creation of continuous riparian buffer strips around perennial and intermittent streams throughout the region. We use a GIS-based analysis to consider the potential of several different buffer-width scenarios to meet milkweed restoration targets. We further estimate the ability of these habitat areas to provide additional functionality in the form of crop pollination and water quality regulation across the entire region. Finally, we estimate the conservative economic value of these ecosystem services and compare it with the lost value of crops associated with each scenario. Results suggest that riparian buffers could be used to meet 10-43% of the total milkweed restoration target of 1.3 billion new stems with moderate management. The value of water quality and pollination benefits provided by buffers is estimated to exceed costs only for our smallest buffer-width scenario, with a cost-benefit ratio of 1:2.05. Larger buffer widths provide more milkweed, but costs to farmers exceed the benefits we were able to quantify. The large-scale restoration of multifunctional riparian corridors thus has the potential to add milkweed stems while also providing a variety of other valuable benefits. This suggests the potential to leverage monarch habitat restoration efforts for the benefit of a wider variety of species and a broader coalition of beneficiaries.

Output from programming code written to summarize monarch butterfly abundance from monitoring data acquired using a modified Pollard walk at custom 2017 GRTS draw sites within select monitoring areas (see SOP 2 in ServCat reference 103367 for methods) of FWS Legacy Regions 2 and 3. Areas monitored included Balcones Canyonlands (TX), Hagerman (TX), Washita (OK), Neal Smith (IA), Necedah (WI) NWRs and several locations near the town of Lamoni, Iowa and private lands in northern Missouri.

Output from programming code written to summarize monarch butterfly abundance from monitoring data acquired using a modified Pollard walk at custom 2017 GRTS draw sites within select monitoring areas (see SOP 2 in ServCat reference 103367 for methods) of FWS Legacy Regions 2 and 3. Areas monitored included Balcones Canyonlands (TX), Hagerman (TX), Washita (OK), Neal Smith (IA), Necedah (WI) NWRs and several locations near the town of Lamoni, Iowa and private lands in northern Missouri.

Output from programming code written to summarize 2018 monarch butterfly abundance from monitoring data acquired using a modified Pollard walk at custom 2017 GRTS draw sites within select monitoring areas (see SOP 2 in ServCat reference 103367 for methods) of FWS Legacy Regions 2 and 3. Areas monitored included Balcones Canyonlands (TX), Hagerman (TX), Washita (OK), Neal Smith (IA) NWRs and several locations near the town of Lamoni, Iowa and northern Missouri. Input data file is named 'FWS_2018_MM_SOP2_for_SAS.csv' and is stored in ServCat reference 136485. See SM 5 (ServCat reference 103388) for dictionary of data fields in the input data file.