BC Conservation Data Centre: Conservation Status Report
Danaus plexippus
Monarch
| Scientific Name: | Danaus plexippus |
|---|---|
| English Name: | Monarch |
| Provincial Status Summary | |
| Status: | S1?B |
| Date Status Assigned: | February 04, 2020 |
| Date Last Reviewed: | February 04, 2020 |
| Reasons: | Monarchs in BC are of Special Concern because of destruction of their hibernation sites in California. Milkweed, the species larval foodplant, is considered a noxious weed by the agricultural industry (Guppy and Shepard 2001). The provincial breeding population requires monitoring and there are also non-breeding migrants in areas without milkweed (Guppy and Shepard 2001). |
| Range | |
| Range Extent: | D = 1,000-5,000 square km |
| Range Extent Comments: | Element occurrence records for the Monarch are mainly from the southern interior regions of BC, although periodic occurrences from the coast are observed, including the lower Fraser Valley and Vancouver Island (Guppy and Shepard 2001). Monarchs are migratory and western populations hibernate in northern California and eastern populations hibernate in Mexico (Guppy and Shepard 2001). Populations in the Kootenays may be the eastern population, elsewhere in BC populations may be the western population (Guppy and Shepard 2001). |
| Area of Occupancy (km2): | U = Unknown |
| Area of Occupancy Comments: | Monarchs feed upon showy milkweed (Asclepias speciosa), the only native milkweed in BC. The patch size or number of plants upon which is needed for larvae in BC is unknown. |
| Occurrences & Population | |
| Number of Occurrences: | BC = 6 - 80 |
| Comments: | Monarchs migrate north into low elevation areas of southern BC (Guppy and Shepard 2001). Monarchs have been observed througout southern BC, with the earliest records being from 1914. Both current and historic element occurrences include Sapperton (New Westminster); Kelowna; Vernon; Oliver; Tofino; Kamloops; Keremeos (Ashnola River valley on the south side of Similkameen River); Cranbrook; Armstrong; and Penticton. Many hobbyists are able to rear Monarchs in captivity on garden milkweed plants, and release these adults into the wild in areas not usually within the range of the species (Guppy and Shepard 2001) thus making it difficult to determine a legitimate element occurrence for the species. |
| Number of Occurrences with Good Viability / Ecological Integrity: | U = Unknown |
| Number of Occurrences Appropriately Protected & Managed: | U = Unknown |
| Comments: | Patches of milkweed, the larval food plant, have been observed in numerous parks and protected areas, although it is unknown if Monarchs use these plants. |
| Population Size: | U = Unknown |
| Comments: | Monarchs are multivoltine in southern North America, and migrate north into low elevation areas of southern BC each summer. Monarchs lay eggs on the milkweed and at least one generation matures successfully each summer in BC. The number of adult Monarchs in BC varies from year to year, but the species is generally uncommon, in the late summer and fall (Guppy and Shepard 2001). |
| Threats (to population, occurrences, or area affected) | |
| Degree of Threat: | B = High |
| Comments: | The dry southern interior habitats continue to be threatened by fragmention as a result of urban/rural land development. Milkweed is widely distributed throughout the southern interior, but may become less common in the future due to implementation of weed control programs as milkweed is considered a noxious weed by the agricultural industry (Guppy and Shepard 2001). There is also destruction of their hibernation sites in California. |
| Trend (in population, range, area occupied, and/or condition of occurrences) | |
| Short-Term Trend: | E = Decline of 30-50% |
| Comments: | There has been increased fragmentation of the dry southern interior habitats as a result of urban/rural land development. Milkweed is widely distributed throughout the southern interior, but may become less common in the future as weed control programs are implemented (Guppy and Shepard 2001). |
| Long-Term Trend: | D = Decline of 50-70% |
| Comments: | There has been fragmentation of the dry southern interior habitats as a result of urban/rural land development. |
| Other Factors | |
| Intrinsic Vulnerability: | A=Highly vulnerable |
| Environmental Specificity: | A=Very narrow. Specialist or community with key requirements scarce. |
| Comments: | Monarchs are multivoltine in southern North America, and migrate north into low elevation areas of southern BC each summer. The monarch's larval foodplant in BC, showy milkweed (Asclepias speciosa), is the only milkweed native to BC and occurs in the dry areas of the southern interior of BC. When fourth instar larvae collected on showy milkweed near Keremeos in late June were reared, adults emerged in mid July (CSG). Many species of milkweed have been recorded as larval foodplants outside of BC as summarized by Malcolm and Brower (1987). |
| Other Rank Considerations: | |
| Information Gaps | |
| Research Needs: | Research of specific habitat requirements (food plant density and size), dispersal and recolonization capabilities, reproductive success and population viability should be conducted. Additional research to assess the potential impacts of predation, parasitism, climatic variation, small population size, and population isolation is also needed. Research is required to assess the potential threats to habitat, including wild fire and removal of milkweed for weed control purposes. Researc to determine patch size necessary to attract Monarchs to an area. |
| Inventory Needs: | Inventory of milkweed plants, native (Asclepias speciosa) and introduced, need to be inventoried. Inventory for A. speciosa was initiated in June 2004 when surveys for other butterfly species were completed. |
| Stewardship | |
| Protection: | |
| Management: | |
| Version | |
| Author: | Heron, J. |
| Date: | December 04, 2012 |
| References | |
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Environment and Climate Change Canada. 2016t. Management Plan for the Monarch (Danaus plexippus) in Canada. Species at Risk Act Management Plan Series. Environment and Climate Change Canada, Ottawa. iv + 45 pp.
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Guppy, C.S., and J.H. Shepard. 2001. Butterflies of British Columbia. UBC Press in collaboration with Royal B.C. Mus. 414pp.
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Please visit the website Conservation Status Ranks for information on how the CDC determines conservation status ranks. For global conservation status reports and ranks, please visit the NatureServe website http://www.natureserve.org/.
Suggested Citation:
B.C. Conservation Data Centre. 2012. Conservation Status Report: Danaus plexippus. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jul 22, 2024).