Correction: Milkweed and floral resource availability for monarch butterflies (Danaus plexippus) in the United States

A Correction on
Milkweed and floral resource availability for monarch butterflies (Danaus plexippus) in the United States

By Lukens L, Thieme J and Thogmartin WE (2024). Front. Ecol. Evol. 12:1330583. doi: 10.3389/fevo.2024.1330583

In the original article, Section 4 Discussion, 4.2 Site type contained errors regarding modeled milkweed densities for developed, rights-of-way, and unclassified grassland sites.

Paragraph 1 originally stated: “Both densities are substantially lower than our model estimates of 190 plants per hectare for random sites in the North and 186 in the South. On the other hand, our model estimate for Developed non-random sites in the North (267 plants/hectare) closely resembled their two highest land use type means for enhanced sites in Chicago.” This has been updated to read:

“Both densities are substantially lower than our model estimates of 777 plants per hectare for random sites in the North and 634 in the South. Our model estimates more closely resemble their two highest land use type means for enhanced sites in Chicago.”

Paragraph 3 originally stated: “Model predictions of densities on northern random and non-random Rights-of-Way ranged from 569–795 plants per hectare (respectively), similar to 508 plants per hectare reported for Asclepias syriaca on Minnesota roadsides (Kasten et al., 2016). Although Kasten et al. (2016) presented mean densities for this species alone (whereas we combined all species except for A. verticillata and A. subverticillata), A. syriaca was the most common species encountered in the North and grew at highest densities on random sites. Kaul and Wilsey (2019) reported a greater mean density on Iowa roadsides (1,274 plants/hectare), but this difference may be attributed to their inclusion of Asclepias verticillata in density calculations, which, as our data indicate (Supplementary Table S1), tends to grow in very high densities.” This has been updated to read:

“Model predictions of densities on northern random and non-random Rights-of-Way ranged from 1,425–2,165 plants per hectare (respectively), greater than the 508 plants per hectare reported for Asclepias syriaca on Minnesota roadsides (Kasten et al., 2016). Kaul and Wilsey (2019) reported a similar mean density on Iowa roadsides (1,274 plants/hectare), but their mean included Asclepias verticillata in density calculations, which, as our data indicate (Supplementary Table S1), tends to grow in very high densities.”

Paragraph 5 originally stated: “Observed milkweed densities for Agricultural Conservation Land (287–390 plants/hectare) and Protected Grassland (399–543 plants/hectare) in the North were lower than Lukens et al. (2020) reported densities on restored conservation grasslands in Minnesota, Wisconsin, and Iowa. Notably, Lukens et al.’s dataset is a subset of the overall IMMP dataset, representing 276 of 2,707 surveys. Model estimates for Unclassified Grassland (303–1,285) closely resembled Lukens et al.’s reported mean density of 1,390 plants per hectare.” This has been updated to read:

“Modeled milkweed densities for Agricultural Conservation Land (576–875 plants/hectare) and Protected Grassland (841–1,277 plants/hectare) in the North were slightly lower than Lukens et al.’s (2020) reported densities on restored conservation grasslands in Minnesota, Wisconsin, and Iowa. Notably, Lukens et al.’s dataset is a subset of the overall IMMP dataset, representing 276 of 2,707 surveys. Model estimates for Unclassified Grassland (1,285–1,951) closely resembled Lukens et al.’s reported mean density of 1,390 plants per hectare.”

We thank S. Choy (U.S. Fish & Wildlife Service) for bringing this matter to our attention. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. The original article has been updated.

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