BC Conservation Data Centre: Conservation Status Report
Hypogymnia heterophylla
seaside bone
| Scientific Name: | Hypogymnia heterophylla |
|---|---|
| English Name: | seaside bone |
| Provincial Status Summary | |
| Status: | S3S4 |
| Date Status Assigned: | April 30, 2023 |
| Date Last Reviewed: | April 30, 2023 |
| Reasons: | A total of 4 occurrences have been documented in British Columbia, most of which appear to have good viablity. All occurrences are restricted to a narrow band of coastal lodgepole pine habitat. No imminent threats have been identified, although severe winter storms and/or DND activities may pose a threat to some EOs. The scope of threats is low, and the severity of threats is moderate. All EOs occur in areas that are protected from development. Total population size is unknown but is estimated at >1000 thalli. The range extent of Hypogymnia heterophylla in BC is ca. 8 square kilometres; the area of occupancy is ca. 12-16 square kilometres. Short-term trends are relatively stable. Long-term trends are unknown. First found in Canada in 1991, H. heterophylla is at the northern edge of its range on southern Vancouver Island (Goward 1996). The BC range currently makes up 100% of the Canadian range but less than one percent of the species' total North American range. The likelihood of a rescue effect is low, although populations in Washington state may provide a source for H. heterophylla populations in Canada (COSEWIC 2008). |
| Range | |
| Range Extent: | A = <100 square km |
| Range Extent Comments: | The range extent is 22.6 square kilometres, calculated using the alpha hull method. |
| Area of Occupancy (km2): | EF = 26-500 |
| Area of Occupancy Comments: | Using GIS tools, AOO index value is 21 cells (each 4 sq km) or 84 sq km. |
| Occurrences & Population | |
| Number of Occurrences: | B = 6 - 20 |
| Comments: | There are 7 subpopulations within 4 documented EOs, distributed within East Sooke Park, Bentinck Island, and Sheringham Point (all southern Vancouver Island). |
| Number of Occurrences with Good Viability / Ecological Integrity: | C = 4 - 12 |
| Comments: | Of the 4 EOs, 3 contained >100 individuals at last census (in 2006), and one contained <100 individuals (COSEWIC 2008). The larger EOs, at least, exhibit favorable characteristics with respect to population size and/or quality and quantity of occupied habitat; and, if current conditions prevail, are likely to persist for the foreseeable future. |
| Number of Occurrences Appropriately Protected & Managed: | C = 4 - 12 |
| Comments: | All 4 EOs occur either in regional parks, DND property, or Fisheries and Oceans property, which provide some measure of protection from development. |
| Population Size: | C = 250 - 1,000 individuals |
| Comments: | As of 2006 there were 4 EOs ranging in size from >10 to >100 individuals, distributed across four locations at East Sooke Park, Bentink Island, and Sheringham Point (all on/near southern Vancouver Island). Total population size is unknown but is estimated at >1,000 thalli (COSEWIC 2008). |
| Threats (to population, occurrences, or area affected) | |
| Degree of Threat: | Localized substantial threat |
| Comments: | [C]No imminent threats have been identified. At East Sooke Regional Park, inadvertent damage could occur due to the passage of hikers, cyclists and dogs along trails through the lodgepole pine stands. Hypogymnia heterophylla at Bentinck Island is potentially in danger of being damaged or eradicated due to the Department of National Defence (DND) use of the island for demolitions, although DND is aware of the locations of H. heterophylla. The primary threat appears to be winter wind storms, stochastic events that are likely to affect only a small proportion of the total population (COSEWIC 2008). |
| Trend (in population, range, area occupied, and/or condition of occurrences) | |
| Short-Term Trend: | G = Relatively Stable (<=10% change) |
| Comments: | [G]The population trend since 1996 is relatively stable, although severe winter storms in 2006/2007 blew down several trees in East Sooke Regional Park, potentially resulting in damage to Hypogymnia heterophylla (COSEWIC 2008). Since downed vegetation will be left on site, any lichens on trees damaged in the storms could potentially continue to be viable for a limited time (COSEWIC 2008). |
| Long-Term Trend: | U = Unknown |
| Comments: | Populations were not monitored prior to 1996, therefore long-term trends are unknown although presumably stable. |
| Other Factors | |
| Intrinsic Vulnerability: | B=Moderately vulnerable |
| Comments: | Hypogymnia heterophylla exhibits moderate intrinsic vulnerability. Demographic rates, including frequency of reproduction and fecundity, are unknown, but populations likely require several years or generations to recover from decreases in abundance. At the same time, the species appears to possess moderate dispersal capability such that extirpated populations generally become reestablished through natural recolonization (unaided by humans). Ecosystem occurrences may be susceptible to changes in composition and structure but tend to recover through natural processes given reasonable time. |
| Environmental Specificity: | B=Narrow. Specialist or community with key requirements common. |
| Comments: | Hypogymnia heterophylla habitat consists primarily of early seral lodgepole pine located on rocky windswept ledges with southwest to western aspects along the coast. Much of the coastline along the southwest coast of Vancouver Island is rocky undulating hills or sandy/gravelly beaches; rocky windswept ledges are less commonly found and thus could be a factor limiting dispersal and spread (COSEWIC 2008). |
| Other Rank Considerations: | First found in Canada in 1991, H. heterophylla is at the northern edge of its range on southern Vancouver Island (Goward 1996). The BC range currently makes up 100% of the Canadian range but less than one percent of the species' total North American range. The likelihood of a rescue effect is low, although populations in Washingtom state may provide a source for H. heterophylla populations in Canada (COSEWIC 2008). |
| Information Gaps | |
| Research Needs: | Current knowledge of Hypogymnia herterophylla is limited to general autecological characteristics and habitat preferences. There is no information on demographic rates such as fecundity or dispersal, and population dynamics have not been monitored, thus long-term population trends are unknown. It is also not known how large the population must be to be self-sustaining. More research is needed to identify critical limiting factors, as well as critical habitat. |
| Inventory Needs: | Hypogymnia heterophylla appears to be naturally rare in Canada, having been collected from only four localities on southern Vancouver Island despite relatively extensive search effort (COSEWIC 2008). Nevertheless, the potential exists for the discovery of additional occurrences as more habitat is inventoried. |
| Stewardship | |
| Protection: | All EOs are in regional parks, DND property, or Fisheries and Oceans property, all of which are protected areas. However, no specific measures are in place to protect Hypogymnia heterophylla within these areas. |
| Management: | During storms clean-up, all downed vegetation should be left on site, in case any living Hypogymnia heterophylla remain on storm-damaged trees (COSEWIC 2008). |
| Version | |
| Author: | Miller, M. and M. Donovan |
| Date: | December 09, 2011 |
| References | |
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Goward, T. 1996. Status report on the Seaside Bone Hypogymnia heterophylla. Rep. submitted to the Comm. on the Status of Endangered Wildl. in Can. (COSEWIC). Ottawa. 36pp.
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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. 2011. Conservation Status Report: Hypogymnia heterophylla. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Feb 1, 2026).