Invasives Restoring Butterflies
By Ruby Waddell
Keywords: restoration, butterflies, plantain, exotic, native
Summary
The Taylors checkerspot butterfly (Euphydryas editha taylori) is an endangered butterfly species native to the prairie-oak ecosystems along the Pacific West Coast of North America (Wildlife Preservation Canada, 2023). This species was once abundant in the region, but has since become threatened by a reduction in suitable habitat due to anthropogenic disturbance, and a significant reduction in native plant species that act as hosts for the butterfly’s eggs and larvae (Buckingham et. al., 2016; Denman Conservancy Association, 2014). In areas where the prairie-oak landscape was disturbed and no longer suitable for some native plant species, the introduced English plantain (Plantago lanceolata) has spread widely (Potter, 2016). Facing this substantial reduction in native host plants, Taylor’s checkerspot butterflies began using the exotic plantain species as a host plant, and 80% of the remaining populations became reliant on it (Severns & Stone, 2016). This exotic host plant is now being used to breed the butterflies for restoration efforts (Denman Conservancy Association, 2014) and is an integral host species for the majority of the existing wild Taylor’s checkerspot butterfly populations (Severns & Stone, 2016). This is an interesting example of changing nature, as this endangered native butterfly species is now using an introduced host plant for its restoration.
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Ecological genealogy
Across Oregon, Washington, and British Columbia, a unique prairie-oak ecosystem has historically characterized the area. This landscape was managed by Indigenous peoples, and included management practices such as prescribed burning (Schultz et. al., 2011). Taylor’s checkerspot butterflies (Euphydryas editha taylori) are a species native to this ecosystem, historically ranging throughout the islands and coastal areas of the west coast (Fig. 1.) (Wildlife Preservation Canada, 2023). In the 1800’s, prior to colonization, they were described to be abundant throughout open landscapes along with other butterfly species (Denman Conservancy Association, 2014). They are considered a keystone species due to their sensitivity to changing conditions and thus their role as an environmental indicator of the health of the larger ecosystem (Wildlife Preservation Canada, 2023). Butterfly species play important roles in providing pollinating services, hosting various parasites and microorganisms, and providing habitat nutrients through excretions (Denman Conservancy Association, 2014).
The once abundant Taylor’s checkerspot butterfly quickly declined in the 1900’s alongside habitat changes driven the displacement of First Nations peoples by European settlement along the Pacific Northwest (Denman Conservancy Association, 2014). European management practices pushed out Indigenous land management practices, resulting in a reduction of deliberately open landscapes (Denman Conservancy Association, 2014). Taylor’s checkerspot butterfly has been considered endangered as of 2000 by COSEWIC and 2003 by SARA because of the anthropogenic disturbances to their habitat and climate conditions (COSEWIC 2011). Taylor’s checkerspot butterfly relies on a host plant to lay its eggs, known as oviposition, and therefore reproduce (Buckingham et. al., 2016). This species has historically used native harsh paintbrush (Castilleja hispida), golden paintbrush (Castilleja levisecta), maiden blue eyed Mary (Collinsia parviflora), and speedwells (Veronica) for oviposition (Potter, 2016; Schultz, 2011). However, these native species have also faced environmental stressors resulting in significant reduction (Potter, 2016). Introduced to the area is English plantain (Plantago lanceolata) an exotic species from Europe that has spread widely in areas where native species have declined, creating space for English plantain to establish (Potter, 2016). In response, Taylor’s checkerspot butterfly has increasingly used this exotic plant species as a host plant for oviposition (Potter, 2016). Now, 80% of extant population of the Taylor’s checkerspot butterfly rely on English plantain (Severns & Stone, 2016). This butterfly species adapted to use the exotic plant as a host, as this species was better able to colonize areas of landscape disturbance in the region compared to native plant species (Singer et. al., 2008). This host plant thrives in disturbed habitat, and its leaves can shade out plants that try to grow nearby, creating difficult abiotic conditions for competing vegetation (Conservation Commission of Missouri, 2024). These factors create an interesting situation for restoration efforts; With Taylor’s checkerspot butterfly using this exotic host plant for oviposition, this case shows how the use of introduced species for restoration may be useful. |
Present tense
Taylor’s checkerspot butterfly is currently federally endangered and provincially red listed in Canada (Islands Trust, 2023), and endangered in Washington and Oregon, United States (U.S. Fish and Wildlife Service, 2013). Breeding programs exist in each province and state within the species’ range, which is now constricted to small areas in the Pacific Northwest (Fig. 2) (Schultz et. al., 2011). English plantain is being used in reintroduction sites of Taylor’s checkerspot butterflies, and this host species seems to be favored even when native species, such as golden paintbrush and maiden blue eyed Mary, are available due to the butterfly’s adaptation to the germination time of English plantain (Haan et. al., 2021; Severns, 2008). Habitat restoration and enhancement efforts have been supported in Washington since 2007 and in Oregon since 2004, in hopes of translocating the individuals bred in captivity to their historically occupied locations (Weiss et. al., 2013; Oregon Zoo, n.d.). However, self-sustaining populations of translocated individuals in these areas has not yet been achieved. In Canada, small populations of Taylor’s checkerspot butterflies were found on Denman Island in British Columbia in 2005, and formal stewardship led by the Denman Conservancy Association (DCA) began in 2008 (Denman Conservancy Association, 2014). The DCA project involves various landowners on Denman Island whose properties were identified as rare meadow habitat and participate by reporting sightings of the butterfly on their land. Another project was planned to release 3000 Taylor’s checkerspot butterfly caterpillars in two rounds, one in 2023 and one in 2024, on Hornby Island, British Columbia (Wildlife Preservation Canada, 2023). These caterpillars are being produced in the Greater Vancouver Zoo breeding facilities, with hopes of eventually releasing up to 6000 caterpillars per year for five years (Wildlife Preservation Canada, 2023). The goal of this project is to have 5 sustainable wild populations in 10 to 20 years, without the need for further intervention. The breeding programs in the southern extent of the range are more focused on preventing the populations from disappearing entirely (Oregon Zoo, n.d.), whereas the breeding programs in the northern extent aim to restore self-sustaining populations resistant to climate change (Wildlife Preservation Canada, 2023).
In Helliwell Provincial Park on Hornby Island, English plantain exists amongst plant species native to the area (GOERT, 2016). It has not outcompeted native species in this region likely because there is less disturbed habitat in the park for it to colonize and there has been significant native species restoration (GOERT, 2016). Plantago lanceolata mainly colonizes around edges of roads and trails or bare areas of disturbed land (Denman Conservancy Association, 2014). Restoration of the prairie-oak ecosystem in Helliwell began in 2014 led by BC Parks and GOERT, specifically starting at the bluff that was historically home to the last Taylor’s checkerspot butterfly population on Hornby Island (GOERT, 2016). Due to the landscape restoration in Helliwell the park now provides little disturbed habitat for plantain to become invasive in the area and the butterflies do not seem to rely solely on the exotic host (GOERT, 2016). English plantains are being used for breeding the late stage larvae that are being released on Hornby, but this has not appeared to affect the success of the reintroduced adult butterflies (Denman Conservancy Association, 2014). |
Future trajectory
When looking at Taylor’s checkerspot butterflies, climate change-induced range shift are important, as the species’ natural habitat and preferred abiotic conditions have already been shifted from historical conditions. As this trend continues, the southerly populations of this butterfly are likely to face increased risk of extinction. The project on Hornby Island is an attempt to lessen this overall pressure on the species, as the populations being reestablished in Helliwell Provincial Park on Hornby Island are the furthest north population of this species. These populations are likely to be the most resistant against climate change as their northern location may be more resistant to climate change-induced range shift, and the large scale and quantity of butterflies being reintroduced may make it less susceptible to disturbance events. It is likely that the southern extent populations will face extirpation if climate conditions become too harsh, or if breeding programs stop at any point.
Disease infecting host plants could become a threat to Taylor’s checkerspot butterflies in the future. In its southern range Plantago lanceolata has faced invasion by a non-native plant pathogen Pyrenopeziza plantaginis (Severns & Guzman-Martinez, 2021). This pathogen causes a disease on the exotic host plant, resulting in the leaves of the plant dying during the winter months (Severns & Guzman-Martinez, 2021). This is also the time of year when Taylor’s checkerspot butterfly larvae feed on this plant, and thus the necrosis of the Plantago lanceolata leaves takes away a key source of food from the developing butterflies (Severns & Guzman-Martinez, 2021). Luckily the restoration projects on Denman and Hornby Islands do not rely on Plantago lanceolata in the wild to such a degree. However, this disease or similar ones could wipe out the southerly populations whose restoration is more reliant on the exotic host plant.
The restoration sites for Taylor’s checkerspot butterflies may be considered at least hybrid if not novel ecosystems due to their use of an exotic host plant for breeding efforts, and the inclusion of this exotic host species within the restored habitat. The inclusion of this non-native species in these restoration sites is a result of the native butterflies becoming reliant on the exotic species, which colonized the disturbed landscapes that were historically full of native prairie-oak species.
The relationship between this exotic host plant and endangered native butterfly now underpins the native’s restoration. The prairie-oak ecosystems that sustain these butterfly populations have always involved continuous human management and thus these ecosystems would likely become overgrown and unsuitable habitat for the native plant and butterfly species if management efforts stopped. As well, due to the invasive potential of species within this landscape, management of people in this area will need to persist in the future. Provincial Parks are not only home to important native species, but are also sites for human recreation, and thus if trail boundaries are not respected, disturbed habitat may arise and become an issue for native species.
Disease infecting host plants could become a threat to Taylor’s checkerspot butterflies in the future. In its southern range Plantago lanceolata has faced invasion by a non-native plant pathogen Pyrenopeziza plantaginis (Severns & Guzman-Martinez, 2021). This pathogen causes a disease on the exotic host plant, resulting in the leaves of the plant dying during the winter months (Severns & Guzman-Martinez, 2021). This is also the time of year when Taylor’s checkerspot butterfly larvae feed on this plant, and thus the necrosis of the Plantago lanceolata leaves takes away a key source of food from the developing butterflies (Severns & Guzman-Martinez, 2021). Luckily the restoration projects on Denman and Hornby Islands do not rely on Plantago lanceolata in the wild to such a degree. However, this disease or similar ones could wipe out the southerly populations whose restoration is more reliant on the exotic host plant.
The restoration sites for Taylor’s checkerspot butterflies may be considered at least hybrid if not novel ecosystems due to their use of an exotic host plant for breeding efforts, and the inclusion of this exotic host species within the restored habitat. The inclusion of this non-native species in these restoration sites is a result of the native butterflies becoming reliant on the exotic species, which colonized the disturbed landscapes that were historically full of native prairie-oak species.
The relationship between this exotic host plant and endangered native butterfly now underpins the native’s restoration. The prairie-oak ecosystems that sustain these butterfly populations have always involved continuous human management and thus these ecosystems would likely become overgrown and unsuitable habitat for the native plant and butterfly species if management efforts stopped. As well, due to the invasive potential of species within this landscape, management of people in this area will need to persist in the future. Provincial Parks are not only home to important native species, but are also sites for human recreation, and thus if trail boundaries are not respected, disturbed habitat may arise and become an issue for native species.
References
Buckingham, D. A., Linders, M., Landa, C., Mullen, L., & LeRoy, C. (2016). Oviposition Preference of Endangered Taylor’s Checkerspot Butterflies (Euphydryas editha taylori) Using Native and Non-Native Hosts. Northwest Science, 90(4), 491–497. https://doi.org/10.3955/046.090.0409
Conservation Commission of Missouri. (2024). English Plantain. Missouri Department of Conservation. https://mdc.mo.gov/discover-nature/field-guide/english-plantain
COSEWIC. (2011). Taylor’s Checkerspot Euphydryas editha taylori. https://www.sararegistry.gc.ca/virtual_sara/files/cosewic/sr_taylors_checkerspot_0911_eng.pdf
Denman Conservancy Association. (2014). Guide to the stewardship of Taylor’s checkerspot Euphydryas Editha Taylori on Denman Island. In Denman Conservancy. https://www.denman-conservancy.org/wp-content/uploads/2014/05/Draft-DCA-Checkerspot-Stew-Guide-HSP-2014.pdf
GOERT. (2016). Ecosystem Restoration in Helliwell Provincial Park – A Backgrounder Report. Garry Oak Ecosystem Recovery Team. Retrieved March 8, 2024, from https://goert.ca/ecosystem-restoration-in-helliwell-provincial-park-a-backgrounder-report/
Haan, N. L., Bowers, M. D., & Bakker, J. D. (2021). Preference, performance, and chemical defense in an endangered butterfly using novel and ancestral host plants. Scientific Reports, 11(1), Article 1. https://doi.org/10.1038/s41598-020-80413-y
Islands Trust. (2019). Conservation status of Denman Island Local Trust Area. In Islands Trust Conservancy. https://islandstrust.bc.ca/document/conservation-status-of-denman-island-2023/
Oregon Zoo. (n.d.). Taylor’s checkerspot butterfly. Retrieved March 6, 2024, from https://www.oregonzoo.org/wildlife/fighting-extinction/taylors-checkerspot-butterfly
Potter, A. E. (2016). DRAFT Periodic Status Review for Taylor’s Checkerspot.
Schultz, C. B., Henry, E., Carleton, A., Hicks, T., Thomas, R., Potter, A., Collins, M., Linders, M., Fimbel, C., Black, S., Anderson, H. E., Diehl, G., Hamman, S., Gilbert, R., Foster, J., Hays, D., Wilderman, D., Davenport, R., Steel, E., … Reader, B. (2011). Conservation of Prairie-Oak Butterflies in Oregon, Washington, and British Columbia. Northwest Science, 85(2), 361–388. https://doi.org/10.3955/046.085.0221
Severns, P. M. (2008). Interactions between two endangered butterflies and invasive, exotic grasses in western Oregon, USA. Endangered Species Update, 25(2), 35–41.
Severns, P. M., & Guzman-Martinez, M. (2021). Plant Pathogen Invasion Modifies the Eco-Evolutionary Host Plant Interactions of an Endangered Checkerspot Butterfly. Insects, 12(3), 246. https://doi.org/10.3390/insects12030246
Severns, P. M., & Stone, J. K. (2016). Pathogen invasion triggers an evolutionary trap for an endangered checkerspot butterfly dependent on an exotic host plant. Biological Invasions, 18(12), 3623–3633. https://doi.org/10.1007/s10530-016-1253-8
Singer, M., Wee, B., Hawkins, S., & Butcher, M. (2008). Rapid Natural and Anthropogenic Diet Evolution: Three Examples From Checkerspot Butterflies. In Specialization, Speciation, and Radiation: The Evolutionary Biology of Herbivorous Insects (pp. 311–324). https://doi.org/10.1525/california/9780520251328.003.0022
Stinson, D. W. 2005. Washington State Status Report for the Mazama Pocket Gopher, Streaked Horned Lark, and Taylor’s Checkerspot. Washington Department of Fish and Wildlife, Olympia. 129+ xii pp.
Weiss, S., MacDonald, B., & Longcore, T. (2013). Prioritization of Information Gaps Critical to Strengthening the Scientific Basis of Habitat Enhancement Planning and Determining Site Readiness for Taylor’s Checkerspot Butterfly Strategy and Recommendations to Address Priority Information Gaps. https://cascadiaprairieoak.org/wp-content/uploads/2013/12/TCB_Task4-5_FinalDocument.pdf
Wildlife Preservation Canada. (2023). Taylor’s Checkerspot (Euphydryas editha taylori). Wildlife Preservation Canada. Retrieved March 2, 2024, from https://wildlifepreservation.ca/species/taylors-checkerspot/
Conservation Commission of Missouri. (2024). English Plantain. Missouri Department of Conservation. https://mdc.mo.gov/discover-nature/field-guide/english-plantain
COSEWIC. (2011). Taylor’s Checkerspot Euphydryas editha taylori. https://www.sararegistry.gc.ca/virtual_sara/files/cosewic/sr_taylors_checkerspot_0911_eng.pdf
Denman Conservancy Association. (2014). Guide to the stewardship of Taylor’s checkerspot Euphydryas Editha Taylori on Denman Island. In Denman Conservancy. https://www.denman-conservancy.org/wp-content/uploads/2014/05/Draft-DCA-Checkerspot-Stew-Guide-HSP-2014.pdf
GOERT. (2016). Ecosystem Restoration in Helliwell Provincial Park – A Backgrounder Report. Garry Oak Ecosystem Recovery Team. Retrieved March 8, 2024, from https://goert.ca/ecosystem-restoration-in-helliwell-provincial-park-a-backgrounder-report/
Haan, N. L., Bowers, M. D., & Bakker, J. D. (2021). Preference, performance, and chemical defense in an endangered butterfly using novel and ancestral host plants. Scientific Reports, 11(1), Article 1. https://doi.org/10.1038/s41598-020-80413-y
Islands Trust. (2019). Conservation status of Denman Island Local Trust Area. In Islands Trust Conservancy. https://islandstrust.bc.ca/document/conservation-status-of-denman-island-2023/
Oregon Zoo. (n.d.). Taylor’s checkerspot butterfly. Retrieved March 6, 2024, from https://www.oregonzoo.org/wildlife/fighting-extinction/taylors-checkerspot-butterfly
Potter, A. E. (2016). DRAFT Periodic Status Review for Taylor’s Checkerspot.
Schultz, C. B., Henry, E., Carleton, A., Hicks, T., Thomas, R., Potter, A., Collins, M., Linders, M., Fimbel, C., Black, S., Anderson, H. E., Diehl, G., Hamman, S., Gilbert, R., Foster, J., Hays, D., Wilderman, D., Davenport, R., Steel, E., … Reader, B. (2011). Conservation of Prairie-Oak Butterflies in Oregon, Washington, and British Columbia. Northwest Science, 85(2), 361–388. https://doi.org/10.3955/046.085.0221
Severns, P. M. (2008). Interactions between two endangered butterflies and invasive, exotic grasses in western Oregon, USA. Endangered Species Update, 25(2), 35–41.
Severns, P. M., & Guzman-Martinez, M. (2021). Plant Pathogen Invasion Modifies the Eco-Evolutionary Host Plant Interactions of an Endangered Checkerspot Butterfly. Insects, 12(3), 246. https://doi.org/10.3390/insects12030246
Severns, P. M., & Stone, J. K. (2016). Pathogen invasion triggers an evolutionary trap for an endangered checkerspot butterfly dependent on an exotic host plant. Biological Invasions, 18(12), 3623–3633. https://doi.org/10.1007/s10530-016-1253-8
Singer, M., Wee, B., Hawkins, S., & Butcher, M. (2008). Rapid Natural and Anthropogenic Diet Evolution: Three Examples From Checkerspot Butterflies. In Specialization, Speciation, and Radiation: The Evolutionary Biology of Herbivorous Insects (pp. 311–324). https://doi.org/10.1525/california/9780520251328.003.0022
Stinson, D. W. 2005. Washington State Status Report for the Mazama Pocket Gopher, Streaked Horned Lark, and Taylor’s Checkerspot. Washington Department of Fish and Wildlife, Olympia. 129+ xii pp.
Weiss, S., MacDonald, B., & Longcore, T. (2013). Prioritization of Information Gaps Critical to Strengthening the Scientific Basis of Habitat Enhancement Planning and Determining Site Readiness for Taylor’s Checkerspot Butterfly Strategy and Recommendations to Address Priority Information Gaps. https://cascadiaprairieoak.org/wp-content/uploads/2013/12/TCB_Task4-5_FinalDocument.pdf
Wildlife Preservation Canada. (2023). Taylor’s Checkerspot (Euphydryas editha taylori). Wildlife Preservation Canada. Retrieved March 2, 2024, from https://wildlifepreservation.ca/species/taylors-checkerspot/