Butterflies, moths, and other insects have been at the center of my endangered species work for thirty years, starting with restoration for the Palos Verdes blue butterfly in the 1990s and including recovery planning, habitat suitability modeling, translocations, captive rearing (with Dr. Jana Johnson and The Butterfly Project at Moorpark College), population assessments, and habitat management for about half of the listed Lepidoptera in California, not to mention a few out of state. Although this work includes species in remote areas such as the Kern Primrose Sphnix Moth, it usually involves species holding on — often precariously — in small, isolated habitat fragments, many surrounded by dense urban or industrial development.
Current Projects
Monitoring, conservation planning, and captive rearing (led by Dr. Johnson) for Palos Verdes blue.
Recovery planning and long-term phenological assessment of El Segundo blue.
Habitat modeling to define the historic range of Kern Primrose Sphinx Moth
Updates
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A Buzz for the Season
For several years running, the Oak Titmice nested in a nest box on the front of our little house in a canyon near UCLA, fledging clutches of young each year. They had started building a new nest this year, which I knew because we clean out the box each year to reduce the potential build-up…
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El Segundo Blue is a full species
One of my side projects in grad school was to analyze data on the endangered El Segundo Blue that had been collected by Dr. Rudi Mattoni at the Los Angeles International Airport dunes. It eventually ended up as a bit larger collaboration with Dr. Cor Zonneveld from the Netherlands (Mattoni et al. 2001) and ended…
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Forthcoming chapter in Butterfly Conservation in North America
Dr. Jaret Daniels has edited a new volume from Springer titled Butterfly Conservation in North America: efforts to help save our charismatic microfauna. Ken Osborne and I have a chapter on conservation efforts in California. Pre-orders are being taken now.
Publications
Edwards, C. B., E. F. Zipkin, E. H. Henry, N. M. Haddad, M. Forister, K. J. Burls, S. P. Campbell, M. R. Douglas, R. G. Drum, E. E. Crone, J. Diffendorfer, E. M. Grames, S. Hoffman-Black, E. A. Larsen, W. Leuenberger, T. Longcore, C. Maffei, J. Michielini, N. Neupane, L. Ries, A. Shapiro, D. Singh, B. Van Deynze, W. E. Thogmartin, and C. B. Schultz. 2025. Rapid butterfly declines across the United States in the 21st century. Science 387:1090–1094.
Edwards, C., C. Schultz, S. Campbell, C. Fallon, E. Henry, K. King, M. Linders, T. Longcore, D. Marschalek, D. Sinclair, A. Swengel, S. Swengel, D. Taron, T. Wepprich, and E. Crone. 2024. Phenological constancy and management interventions predict population trends in at-risk butterflies. Journal of Applied Ecology 61:2455–2469.
Longcore, T., C. Rich, and S. Weiss. 2021. Essay: Nearly all California Monarch overwintering groves require non-native trees. California Fish and Wildlife 106(3):220–225.
Dupuis, J.R., J.C. Oliver, B.M.T. Brunet, T. Longcore, J.J. Johnson, and F.A.H. Sperling. 2018. Genomic data indicate ubiquitous evolutionary distinctiveness among populations of California metalmark butterflies. Conservation Genetics 19(5):1097–1108.
Longcore, T., C. S. Lam, P. Kobernus, E. Polk, and J. P. Wilson. 2010. Extracting useful data from imperfect monitoring schemes: endangered butterflies at San Bruno Mountain, San Mateo County, California (1982–2000) and implications for habitat management. Journal of Insect Conservation 14(4):335–346.
Longcore, T., and C. Rich. 2008. Invertebrate conservation at the gates of hell. Wings: Essays on Invertebrate Conservation.
Jump, P., T. Longcore, and C. Rich. 2006. Ecology and distribution of a newly discovered population of the federally threatened Euproserpinus euterpe (Sphingidae). Journal of the Lepidopterists’ Society 60(1):41–50.
Longcore, T., R. Mattoni, and A. Mattoni. 2005. Salvage of pupae as a mitigation measure for impacts to endangered butterfly habitat. Journal of the Lepidopterists’ Society 59(2):116–117.
Longcore, T., C. S. Lam, and J. P. Wilson. 2004. Analysis of butterfly survey data and methodology from San Bruno Mountain Habitat Conservation Plan (1982–2000) 1. Status and trends. Los Angeles, CA, University of Southern California GIS Research Laboratory Technical Report No. 1.
Longcore, T. 2004. Analysis of butterfly survey data and methodology from San Bruno Mountain Habitat Conservation Plan (1982–2000) 2. Survey Methodology. Los Angeles, CA, University of Southern California GIS Research Laboratory Technical Report No. 2.
Longcore, T., R. Mattoni, C. Zonneveld, and J. Bruggeman. 2003. INsect Count Analyzer: a tool to assess responses of butterflies to habitat restoration. Ecological Restoration 21(1):60–61. Developed specifically for univoltine insects. See http://www.urbanwildlands.org/INCA/.
Mattoni, R., T. Longcore, Z. Krenova, and A. Lipman. 2003. Mass rearing of the endangered Palos Verdes blue butterfly (Glaucopsyche lygdamus palosverdesensis: Lycaenidae). Journal of Research on the Lepidoptera 37:55–67.
Zonneveld, C., T. Longcore, and C. Mulder. 2003. Optimal schemes to detect the presence of insect species. Conservation Biology 17(2):476–487.
Longcore, T. 2003. Terrestrial arthropods as indicators of restoration success in coastal sage scrub (California, U.S.A.). Restoration Ecology 11(4):397–409.
Mattoni, R., T. Longcore, C. Zonneveld, and V. Novotny. 2001. Analysis of transect counts to monitor population size in endangered insects: the case of the El Segundo blue butterfly, Euphilotes bernardino allyni. Journal of Insect Conservation 5(3):197–206.
Lipman, A., T. Longcore, R. Mattoni, and Y. Zhang. 1999. Habitat evaluation and reintroduction planning for the endangered Palos Verdes blue butterfly. UCLA Department of Geography. Final Technical Report to California Department of Fish and Game. 44 pp.
Mattoni, R., T. Longcore, and V. Novotny. 2000. Arthropod monitoring for fine-scale habitat analysis: a case study of the El Segundo sand dunes. Environmental Management 25(4):445–452.
Longcore, T., R. Mattoni, G. Pratt, and C. Rich. 2000. On the perils of ecological restoration: lessons from the El Segundo blue butterfly. Pp. 281–286 in Keeley, J., M. Baer-Keeley, and C. J. Fotheringham, eds. 2nd Interface Between Ecology and Land Development in California, U.S. Geological Survey Open-File Report 00-62, Sacramento, CA.
Mattoni, R., G. F. Pratt, T.R. Longcore, J. F. Emmel and J. N. George. 1997. The endangered quino checkerspot butterfly, Euphydryas editha quino (Lepidoptera: Nymphalidae). Journal of Research on the Lepidoptera 34:99–118.
Longcore, T. 1997. The endangered Delhi Sand Dunes. Western Tanager 63(8):1–2.
Reports
Mission Blue
MacDonald, B., T. Longcore, and S. B. Weiss. 2012. Status and Variability of Mission Blue Butterfly Populations at Milagra Ridge, Marin Headlands, and Oakwood Valley. Report to Golden Gate National Parks Conservancy. The Urban Wildlands Group, Los Angeles. 69 pp.
Miami Blue
Longcore, T. 2013. Assessment of Recovery Strategies for Miami Blue Butterfly. Report to U.S. Fish and Wildlife Service (Agreement No. F12AP00812). The Urban Wildlands Group, Los Angeles. 44 pp.
Taylor’s Checkerspot
MacDonald, B., T. Longcore, and S. Weiss. 2012. Taylor’s checkerspot habitat enhancement review and strategy development. Synthesis of cooperator’s assessments of current knowledge and information gaps for improving habitat enhancement efforts and determination of site readiness for Taylor’s checkerspot butterflies in South Puget Sound lowlands. The Urban Wildlands Group (report to Center for Natural Lands Management). 29 pp. (October 15, 2012).
MacDonald, B., T. Longcore, and S. Weiss. 2012. Taylor’s checkerspot habitat enhancement review and strategy development. Annotated bibliography: improving habitat enhancement efforts and determination of site readiness for Taylor’s checkerspot butterflies in South Puget Sound lowlands. The Urban Wildlands Group (report to Center for Natural Lands Management). 86 pp. (December 16, 2012).
MacDonald, B., T. Longcore, and S. Weiss. 2013. Taylor’s checkerspot habitat enhancement review and strategy development. Summary of existing datasets. The Urban Wildlands Group (report to Center for Natural Lands Management). 58 pp. (May 5, 2013).
MacDonald, B., T. Longcore, and S. Weiss. 2013. Taylor’s checkerspot habitat enhancement review and strategy development: 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. The Urban Wildlands Group (report to Center for Natural Lands Management). 24 pp. (November 25, 2013).
Quino Checkerspot
Longcore, T., and T. Bonebrake. 2012. Captive Propagation and Release Plan for Quino Checkerspot Butterfly (Euphydryas editha quino). The Urban Wildlands Group (report to U.S. Fish and Wildlife Service). 35 pp. (September 25, 2012).
Laguna Mountains Skipper
Johnson, J., T. Longcore, A. Clause, A. Lansing, D. Renner, A. Romero, B. Messerschmidt, B. Pickett, P. Kores, and K. Courtney. 2010. Captive rearing of Laguna Mountain Skipper (Pyrgus ruralis lagunae): final report. The Urban Wildlands Group (U.S. Fish and Wildlife Service Cooperative Agreement No. 814307J024). 26 pp. (September 8, 2010).
Anderson, A., A. Eidson, P. Howorth, K. H. Osborne, E. Porter, S. Strahm, K. Winter, S. Wynn, and T. Longcore. 2024. Reintroduction of Laguna Mountains Skipper: 2023 Progress Report. The Urban Wildlands Group. 21 pp. (January 22, 2024).
Anderson, A., A. Eidson, P. Howorth, K. H. Osborne, E. Porter, S. Strahm, K. Winter, S. Wynn, and T. Longcore. 2025. Reintroduction of Laguna Mountains Skipper: 2024 Progress Report. The Urban Wildlands Group. 19 pp. (March 5, 2025).