Recovery Strategy for the Eastern Prickly Pear Cactus (Opuntia humifusa) in Canada
- Recommendation and Approval Statement
- Recovery Team
- Strategic Environmental Assessment Statement
- Executive Summary
- Recovery Feasibility Summary
- List of Figures
- List of Tables
- 1. COSEWIC Species Assessment Information
- 2. Eastern Prickly Pear Cactus Status Information
- 3. Description of the Species and its Needs
- 4. Threat Identification
- 5. Population and Distribution
- 6. Additional Information Requirements
- 7. Broad Strategies and Approaches to Recovery
- 8. Critical Habitat Identification
- 9. Activities Likely to Result in the Destruction of Critical Habitat
- 10. Habitat Conservation
- 11. Measuring Progress
- 12. Statement on Action Plans
- 13. References
- Appendix 1: Effects on the Environment and Other Species
5. Population and Distribution
The range of the Eastern Prickly Pear Cactus extends from Massachusetts through extreme southwestern Ontario, west to Minnesota and south to Oklahoma and Florida (Figure 1). The Canadian population represents much less than one percent of the global abundance of this species. The species is common throughout the southern and eastern parts of its United States range. However, the species' conservation status rank is S1 (Critically imperiled) in Wisconsin and S3 (Vulnerable) in Iowa, Ohio, Pennsylvania and Connecticut (NatureServe 2009).
In Canada, the Eastern Prickly Pear Cactus reaches the northern edge of its range in the southern tip of Ontario. Extant, native populations are only known to occur at two locations in southwestern Ontario: two populations in Point Pelee National Park in Essex County and one in Fish Point Provincial Nature Reserve on Pelee Island (Figure 2).
The two distinct, native, Eastern Prickly Pear Cactus sites in Point Pelee National Park - one in primary successional shoreline areas and the other located in secondary successional, abandoned farm field sites, total 2 070 individuals (VanDerWal et. al. 2007a). A single site exists at Fish Point Provincial Nature Reserve on Pelee Island totaling 11 individuals (S. Dobbyn pers. comm. 2009). In addition to these native populations, there are five known populations of planted Eastern Prickly Pear Cactus in southwestern Ontario for which the origin is unknown, or suspected to be from one of the two native populations. Note that planted populations are not considered part of the Endangered Canadian population, but may potentially play a role in their recovery. The COSEWIC Reason for Designation considers only the two native populations (since determined to be three native populations at two locations) in its decision. There are also six populations of unconfirmed origin that are now extirpated (Table 2).
|Population - Site Name||Location||Origin||Status|
|Fish Point Provincial Nature Reserve (1 population)||Pelee Island, Essex County||Native||Extant|
|Point Pelee National Park (2 populations)||Point Pelee National Park, Essex County||Native||Extant|
|Chatham-Kent Roadside||Municipality of Chatham-Kent||Unknown (P.A. Woodliffe pers. comm. 2005)||Extant|
|Rondeau Provincial Park||Municipality of Chatham-Kent||Introduced presumably from Fish Point Provincial Nature Reserve (P.A. Woodliffe pers. comm. 2003)||Extant|
|Howard Township Cemetery||Howard Township, Municipality of Chatham-Kent||Introduced from Point Pelee National Park (White 1998)||Extant|
|Turkey Point||Norfolk County||Introduced from an unknown location (P. Carson pers. comm. 2003)||Extant|
|South barrier beach of Big Creek Marsh||Port Rowan, Norfolk County||Introduced (S. Brinker pers. comm. 2008, J. Robinson pers. comm. 2008)||Extant|
|Cedar Beach||Colchester South Township, Essex County||Unknown (no voucher)||Extirpated|
|Harwich Township Cemetery||Harwich Township, Municipality of Chatham-Kent||Introduced from Point Pelee National Park (White 1998)||Extirpated|
|Bradley's Marsh||Dover Township, Municipality of Chatham-Kent||Unknown (no voucher)||Extirpated|
|West of Port Stanley||Elgin County||Unknown (no voucher)||Extirpated|
|Long Point||Norfolk County||Unknown (Macoun 1883, no voucher)||Extirpated|
|Ruscom Shores Conservation Area||Essex County||Unknown (P.A. Woodliffe pers. comm. 2005)||Extirpated|
The demographic record for Canadian populations is too inconsistent to accurately assess population trends, although some losses are known to have occurred. To more accurately estimate the size of the populations at Point Pelee National Park, population size was determined by using "microsites" as a surrogate. A microsite represents one or more groups of cacti less than 1.0 m from other groups (Lovett-Doust et al. 2004). It was estimated that each Point Pelee National Park microsite contains, on average, six individuals. Based on this, approximately 2 070 naturally established individuals occur in 345 microsites at Point Pelee National Park - 209 microsites along the west beach and 136 in the Park interior, approximately 250 m from the west beach (VanDerWal et al. 2007a). There are five microsites containing only 11 individuals at Fish Point Provincial Nature Reserve (S. Dobbyn pers. comm. 2009).
In Point Pelee National Park, the average age of microsites, the number of stems per microsite and the number of reproductive individuals in the population have declined (VanDerWal et al. 2007a). At the same time, the average number of fruits recorded per stem has increased, although this increased emphasis on sexual reproduction may be a stress response to declining habitat suitability. Based on the size, genetic variability and recruitment levels of Point Pelee National Park's existing populations, the populations are thought to be viable (L. Lovett-Doust pers. comm. 2005). In contrast, the viability of the Fish Point Provincial Nature Reserve population is questionable due to the small number of microsites and individuals and an apparent lack of recruitment (L. Lovett-Doust pers. comm. 2005).
Based on the information presented above, the population and distribution objectives for Eastern Prickly Pear Cactus are:
- To maintain the current number of microsites (345) of the Eastern Prickly Pear Cactus in Point Pelee National Park over the next five years, and to increase the total number of microsites by 5% over the next 10 years.
- To maintain the population size (five microsites) at Fish Point Provincial Nature Reserve on Pelee Island over the next five years.
- Date Modified: