SPECIES STATUS ASSESSMENT Marron bacora (Solanum conocarpum) VERSION 1.0 Photo by: USFWS April 2019 U.S. Fish and Wildlife Service Southeast Region Caribbean Ecological Service Field Office Boquerón, Puerto Rico Solanum conocarpum Species Status Assessment 2019 This document was prepared by Jaime Yrigoyen, Omar Monsegur, Maritza Vargas, José Cruz-Burgos, and Marelisa Rivera (U.S. Fish and Wildlife Service - Caribbean Ecological Services Field Office) with assistance from Andreas Moshogianis, Kaye London and Erin Rivenbark (U.S. Fish and Wildlife Service - Southeast Regional Office). Valuable peer review of a draft of this document was provided by Jennifer Possley (Conservation Program Manager, Fairchild Tropical Botanic Garden). Suggested citation: U.S. Fish and Wildlife Service. 2019. Species status assessment of Marron bacora (Solanum conocarpum), Version 1.0. U.S. Fish and Wildlife Service Southeast Region, Caribbean Ecological Services Field Office, Boquerón, 2 Solanum conocarpum Species Status Assessment 2019 EXECUTIVE SUMMARY Marron bacora is a rare, tropical dry forest shrub that was once thought to be only found on St. John in the U.S. Virgin Islands; an additional population was discovered on Tortola in the British Virgin Islands in 2018. When the species was petitioned to be listed in 1996, it was listed as a candidate species, Solanum conocarpum, February 22, 2011 (76 FR 9722). When the US Fish and Wildlife Service (Service) was petitioned to list the species, there were only two known wild individuals, one located in the Virgin Islands National Park (VINP) and the other on private land. By 2011, there were 198 wild individuals documented at 8 locations and propagation of the species led to the augmentation of 5 of those locations with 243 individuals, for a total of 441 individuals. Since 2011 the populations have been assessed several times revealing declining numbers at all locations. In 2017, population assessments revealed that the species was then known by 127 wild and 67 introduced individuals, for a total of 194 at 7 locations. The known number of individuals had been reduced by 56%, 3 of the original populations had become extirpated and two new populations were recently discovered. Post Hurricanes Irma and Maria assessments in 2018 revealed a slight increase in the numbers of individuals to 238 (mainly juveniles). Although virtually no natural recruitment had been documented in the wild since 2011, 40 seedlings were observed at the largest known population on St. John. In addition to the documenting 40 seedlings, post hurricane assessments in the British Virgin Islands led to the discovery of 46-48 individuals of marron bacora. The total known individuals of marron bacora in 2018 was 324 at 8 locations, 7 locations in the USVI and 1 in the BVI. Marron bacora has a fragmented distribution due to land clearing and development that has occurred since the 1700s. Although most of the known locations are on National Park Service (NPS) land the largest population may be threatened by development and habitat fragmentation in the near future, as neighboring habitat extend to private lands. Feral ungulates, including white-tailed deer, goats, pigs, and donkeys have been introduced to many of the islands in the past. White-tailed deer were introduced to St. John beginning in the early 1700s and up through the early 1900s. The white-tailed deer in particular are at very high densities on St. John. Although the deer do not heavily graze on marron bacora, it is hypothesized that the depredation of their fruit by these feral ungulates has led to low levels of natural recruitment across its range. In addition, other threats to the species include; sap sucking insects, small population sizes, fragmented/isolated populations and a vulnerability to stochastic events. Marron bacora is a dioecious obligate outcrosser and thus self-incompatible so it is important to take the ratio of mature male to female plants into consideration when evaluating the viability of a population. Under greenhouse conditions marron bacora may reach sexual maturity in two years, however, this is not common in the wild populations. To evaluate the viability of the species, which is the likelihood of persistence over the long term, 3 Solanum conocarpum Species Status Assessment 2019 we utilized the concepts of resilience, redundancy and representation. Marron bacora is known from a small geographic area with little connectivity and therefore has low representation. Redundancy is low due to an apparent reduction on the range of the species and the low number of known viable populations. All known populations are most likely below the estimated minimum viable population level, thus, resilience is low. 4 Solanum conocarpum Species Status Assessment 2019 Table of Contents Executive Summary 3 Table of Contents 5 List of Tables and Figures 9 Chapter 1. Introduction and SSA Framework 11 Chapter 2. Species Life History and Ecology 13 2.1 Morphology 13 2.2 Taxonomy 13 2.3 Genetic Diversity 14 2.4 Phenology and Reproduction 14 2.5 Survival Rates, Lifespan, and Demographic Trends 17 2.6. Habitat 18 2.7 Geographic Range 19 2.7.1 Historical Range 19 2.7.2 Current Range 20 Chapter 3. Population Level Current Conditions 22 3.1 Nanny Point (St. John, USVI) 22 3.2 Friis Bay (St. John, USVI) 25 3.3 John’s Folly (St. John, USVI) 26 3.4 Brown Bay Trail (St. John, USVI) 27 3.5 Reef Bay Trail (St. John, USVI) 28 3.6 Reef Bay Valley (St. John, USVI) 29 3.7 Europa Ridge (St. John, USVI) 29 3.8 Sabbat Point (St. John, USVI) 29 3.9 Base Hill (St. John, USVI) 29 5 Solanum conocarpum Species Status Assessment 2019 3.10 Brown Bay Ridge (St. John, USVI) 29 3.11 Sabbath Hill (Tortola, BVI) 30 3.2 Range of Estimated Potential Habitat on St. John, USVI 30 Chapter 4. Summary of Individual, Population and Species Requirements 31 4.1 Requirements of Individuals 31 4.1.1 Habitats 31 4.1.2 Reproduction 32 4.1.3 Precipitation 32 4.2 Requirements of Populations 33 4.2.1 Minimum Viable Population 33 4.2.2 Size of Habitat Patch 34 4.3 Requirements of Species 34 Chapter 5. Factors Affecting the Survival of marron bacora: Threats 36 5.1 Factors Affecting the Viability of the Species 36 5.1.1 Demographic consequences of small population size and density 36 5.1.2 Genetic consequences of small population size 36 5.1.3 Human Induced Fires 36 5.1.4 Climate Change and Hurricanes 37 5.1.5 Invasive Species 37 5.1.6 Insect Pests and Pathogens 40 5.1.7 Phenology and Breeding System 41 5.1.8 Recreation 41 5.1.9 Conservation Measures 42 5.1.10 Summary 43 5.2 Climate Change 44 6 Solanum conocarpum Species Status Assessment 2019 5.2.1 Background 44 5.2.2 Temperature, Precipitation and Drought Stress 46 5.2.3 Life Zones 49 5.2.4 Storm Frequency and Ferocity 51 5.2.5 Sea Level Rise 53 5.2.6 Potential Threats to Ecosystems 53 Chapter 6. Future Climatic Scenarios 55 6.1 Precipitation and Drought Conditions 55 6.2 Life Zones 55 6.3 Summary 55 6.4 Future Scenarios 56 6.4.1 Scenario I Description 56 6.4.2 Scenario II Description 56 6.4.3 Scenario III Description 57 6.4.4 Likelihood of Scenarios 57 6.5 Future Resilience 57 6.5.1 Nanny Point (St. John, USVI) 59 6.5.2 John’s Folly (St. John, USVI) 60 6.5.3 Brown Bay Trail (St. John, USVI) 61 6.5.4 Friis Bay (St. John, USVI) 62 6.5.5 Base Hill (St. John, USVI) 62 6.5.6 Reef Bay Trail (St. John, USVI) 63 6.5.7 Brown Bay Ridge (St. John, USVI) 63 6.5.8 Sabbat Point (St. John, USVI) 64 6.5.9 Reef Bay Valley (St. John, USVI) 64 6.5.10 Europa Ridge (St. John, USVI) 64 7 Solanum conocarpum Species Status Assessment 2019 6.5.11 Sabbath Hill (Tortola, BVI) 64 6.5.12 Future Propagation and Reintroductions 65 6.6 Future Resilience 65 6.7 Future Redundancy 66 6.8 Future Representation 66 VIII. Literature Cited. 67 Appendix A. Population Resilience Tables. 73 8 Solanum conocarpum Species Status Assessment 2019 List of Figures 1. Figure 1. SSA Framework’s Three Basic Stages 12 2. Figure 2. Drawings of (a) pistillate flower and (b) staminate flower 15 3. Figure 3. Photos of (a) pistillate flower and (b) staminate flower 16 4. Figure 4. Distribution map of marron bacora 21 5. Figure 5. Map of Nanny Point 24 6. Figure 6. Photo of downed marron bacora after Hurricane Irma 25 7. Figure 7. Trail Cam photos: Pre and post Hurricane Irma at Nanny Point 26 8. Figure 8. Map of John’s Folly 27 9. Figure 9. Map of Brown Bay Trail 28 10. Figure 10. Habitat Suitability Map of St. John 31 11. Figure 11. Average rainfall chart for St. John, USVI 33 12. Figure 12. Rapid View of SSA Assessment 35 13. Figure 13. Photo, Nanny Point before and after 2017 hurricanes 38 14. Figure 14. Distribution map of invasive plants at Nanny Point 39 15. Figure 15. Photos of guinea grass encroaching on marron bacora habitat 39 16. Figure 16. Trail Cam photos of deer in Nanny Point population 40 17. Figure 17. Photos of Jacaranda insects on marron bacora 41 18. Figure 18. Future projected temperature changes 46 19. Figure 19. Projected precipitation changes for the US Caribbean 47 20. Figure 20. Temperature projections for Puerto Rico under 3 scenarios 48 21.