Recovery Strategy for the Dwarf Hackberry (Celtis tenuifolia) in Canada [Proposed] 2011

Recovery Strategy for the Dwarf Hackberry (Celtis tenuifolia) in Canada

Recommendation and Approval Statement
Executive Summary
Recovery Feasibility Summary
1. Cosewic Species Assessment Information
2. Species Status Information
3. Species Information

4. Threats

5. Population and Distribution Objectives
6. Broad Strategies and General Approaches to Meet Objectives

7.Critical Habitat

8. Measuring Progress
9.Statement on Action Plans
Appendix A:Effects On The Environment And Other Species
Appendix B:Critical Habitat Maps

Recommended citation:

Parks Canada Agency. 2011. Recovery Strategy for Dwarf Hackberry (Celtis tenuifolia) in Canada [Proposed]. Species at Risk Act Recovery Strategy Series. Parks Canada Agency. Ottawa. vi + 41 pp.

For copies of the recovery strategy, or for additional information on species at risk, including COSEWIC Status Reports, residence descriptions, action plans, and other related recovery documents, please visit the Species at Risk Public Registry (

Cover illustration: K. Dunster, 2009.

Également disponible en français sous le titre
« Programme de rétablissement du micocoulier rabougri (Celtis tenuifolia) au Canada »

© Her Majesty the Queen in Right of Canada, represented by the Minister of the Environment, 2011. All rights reserved.
ISBN to come
Catalogue no. to come

Content (excluding the illustrations) may be used without permission, with appropriate credit to the source.

The federal, provincial, and territorial government signatories under the Accord for the Protection of Species at Risk (1996) agreed to establish complementary legislation and programs that provide for effective protection of species at risk throughout Canada. Under the Species at Risk Act (S.C. 2002, c.29) (SARA), the federal competent ministers are responsible for the preparation of recovery strategies for listed Extirpated, Endangered, and Threatened species and are required to report on progress within five years.

The Minister responsible for the Parks Canada Agency and Environment Canada (the Minister of the Environment) is the competent minister for the recovery of the Dwarf Hackberry and has prepared this strategy, as per section 37 of SARA. It has been prepared in cooperation with Ontario Ministry of Natural Resources, including Ontario Parks, the Department of National Defence, First Nations, local government and non-government organizations, and independent experts.

Success in the recovery of this species depends on the commitment and cooperation of many different constituencies that will be involved in implementing the directions set out in this strategy and will not be achieved by Parks Canada Agency and Environment Canada, or any other jurisdiction alone. All Canadians are invited to join in supporting and implementing this strategy for the benefit of the Dwarf Hackberry and Canadian society as a whole.

This recovery strategy will be followed by one or more action plans that will provide information on recovery measures to be taken by Parks Canada Agency and Environment Canada and other jurisdictions and/or organizations involved in the conservation of the species. Implementation of this strategy is subject to appropriations, priorities, and budgetary constraints of the participating jurisdictions and organizations.

The Parks Canada Agency led the development of this federal recovery strategy, working together with the other competent minister for this species under the Species at Risk Act. The Chief Executive Officer, upon recommendation of the relevant Park Superintendent and Field Unit Superintendent, hereby approves this document indicating that Species at Risk Act requirements related to recovery strategy development (sections 37-42) have been fulfilled in accordance with the Act.


All competent ministers have approved posting of this recovery strategy on the Species at Risk Public Registry.

Background information was gathered and assembled into this recovery strategy by Katherine Dunster of Unfolding Landscapes. The recovery components of this document were developed during a two-day recovery strategy writing workshop. The final document was then assembled and refined by Katherine Dunster and Vicki McKay, Species at Risk Recovery Specialist, Parks Canada Agency (PCA), following reviews by agencies, non-government organizations, and individuals.

The following recovery strategy writing workshop participants provided significant input into the formation of this document: Marie Archambault, Vicki McKay, and Kara Vlasman (PCA); Jennifer Rowland (Department of National Defence); Chief Louise Hillier and Liz Wenzler (Caldwell First Nation); Sandy Dobbyn and Margie Wilkes (Ontario Parks, Ontario Ministry of Natural Resources [OMNR]); Malcolm Boyd (Lambton Wildlife Inc.); and John Ambrose and Katherine Dunster (independents). Thanks are also due to workshop facilitators Steve and Cobi Sauder of Kayak Consulting. Mike Oldham, Wasyl Bakowsky, Sam Brinker, Martina Furrer, and Mikhail Paramonov (Natural Heritage Information Centre, OMNR); Todd Norris and Karen Hartley (OMNR); Mhairi McFarlane (Nature Conservancy of Canada); Muriel Andreae and Chris Durand (St. Clair Region Conservation Authority); Tracey Boitson (Ausable Bayfield Conservation Authority); Sharlene Polman (Lower Trent Conservation); Amy Dickens (Quinte Conservation); and John Ambrose, Malcolm Boyd, Vivian Brownell, and Donald Craig (independents) provided records, data layers, and/or insight into species observations and locations. Marie Archambault and Sandy Dobbyn and Laura Bjorgan (Ontario Parks, OMNR) are thanked for their critical habitat contributions. Josh Keitel (PCA) determined the Canadian extent of occurrence and completed critical habitat and Canadian distribution mapping. Valerie Minelga (PCA) assisted with the strategic environmental assessment and Richard Pelltier (U.S. Geological Survey) determined the proportion of Dwarf Hackberry’s area of occupancy within Canada.

Dwarf Hackberry (Celtis tenuifolia), designated as Threatened in Canada, is a small, stiffly-branched, tree. It typically reproduces sexually and requires fruit-eating birds for long-distance seed dispersal. A number of species depend on it and other hackberry species for their life cycles.

As a disjunct species, Dwarf Hackberry is found over 1 000 km north of the geographical centre of its range in six naturally isolated and fragmented southern Ontario populations. Here, it has adapted to two very different, marginal substrates – dry, sandy soils found along the dynamic shores of Lake Erie, in the more stabilized inland dunes paralleling the Lake Huron shoreline, and on kame ridge tops above the Trent River and on Hastings County and formerly on Pelee Island alvars. It is moderately shade intolerant, requiring prairie or savanna habitats or forest canopy edges or openings for seedling survival. Dwarf Hackberry is restricted to several rare plant communities, with a limited southern Ontario distribution. In Essex and Lambton Counties, it occurs in popular, coastal recreation areas. In Hastings County, it is found on private properties valued for their sand and limestone resources.

With the exception of Point Pelee National Park, population sizes are thought to be relatively stable. A new Lambton County survey has documented many more trees than were previously thought to exist and more are expected to be discovered with future surveys. The range wide number of known, naturally-occurring, mature (fruit-producing) trees and saplings (over 1.0 m in height) is currently around 7 200 individuals. In addition, over 1 500 seedlings occur, most in the Lambton County population.

In order to recover the species, altered or lost disturbance regimes that normally limit habitat succession, detrimental species (bark beetles; snails; White-tailed Deer (Odocoileus virginianus); as well as exotic, invasive, and allelopathic plants), inappropriate logging, development, aggregate extraction, and the impacts of recreational activities need to be addressed.

The population and distribution objectives for Dwarf Hackberry are 1) to halt the apparently steep decline in the species’ population size at Point Pelee National Park and 2) to maintain populations at the other five extant locations (Pelee Island, Lambton County, Point Anne Alvar, Stirling Slope Complex Area of Natural and Scientific Interest [ANSI], and Salmon River Alvar ANSI [Lonsdale]) in suitable habitat.

The broad strategies to be taken to address the threats to the survival and recovery of the species are presented in Section 6.2, Strategic Direction for Recovery.

This recovery strategy identifies critical habitat for the Dwarf Hackberry in Canada, to the extent possible at this time, based on the best available information. Occupancy-based approaches (appropriate vegetation types where available and a tree root zone approach that includes intervening, suitable habitat in other situations) are used. Activities likely to result in the destruction of critical habitat have been identified, while a schedule of studies lists the additional steps required to complete critical habitat identification. One or more action plans will be completed for the Dwarf Hackberry by June 2016.

Recovery of Dwarf Hackberry in Canada is considered biologically and technically feasible. The species meets all four criteria for assessing the feasibility of recovery presented in the draft Government of Canada Species at Risk Act Policies (2009), as described below.

  1. Individuals of the wildlife species that are capable of reproduction are available now or in the foreseeable future to sustain the population or improve its abundance.
    Reproductive populations remain in the protected areas of Point Pelee National Park (mainland), Fish Point Provincial Nature Reserve (Pelee Island), and The Pinery Provincial Park (Lambton County). Substantial reproductive populations also remain in and around the Lambton County Heritage Forest (Lambton County). Six additional Lambton County sites have several to multiple trees of reproductive age. These populations will help to ensure the survival of Dwarf Hackberry and could act as source populations should plantings be required for species recovery. In addition, the University of Guelph Arboretum maintains a living gene bank of Dwarf Hackberry trees from Canadian (Ontario) populations that are producing seeds suitable for repatriation efforts.
  2. Sufficient suitable habitat is available to support the species or could be made available through habitat management or restoration.
    Sufficient habitat is currently available to support the species, particularly in its core Canadian range along the eastern shore of Lake Huron and the north shore of Lake Erie. Dunster (1992) suggests that the species has not fully exploited available habitats, or reached its potential climatic range limits. Suitable habitat is being maintained through natural processes acting in the dynamic, coastal shoreline environments where Dwarf Hackberry is typically found and/or is being restored there (e.g. at Point Pelee National Park). Habitat at inland sites is being maintained to some extent by other forms of disturbance and/or limiting conditions (e.g. the temperature extremes and limited nutrient availability associated with alvars).
  3. The primary threats to the species or its habitat (including threats outside Canada) can be avoided or mitigated.
    There are no unavoidable threats to the species or its habitat that preclude recovery. Human actions related to development, shoreline modification, and inappropriate recreational use can be curbed through education, stewardship, and enforcement. Limestone quarrying in eastern Ontario alvars and the potential expansion of sand extraction activities at other sites can also be avoided or mitigated. Further alteration of natural processes can be prevented and work can be done to restore the damage already done. Steps can and are being taken to manage habitat succession and the impacts of plant competition. While the degree of threat posed by bark beetles and snails at Point Pelee National Park is known, the reasons for infestations are not. Infestations are not known to occur in other populations.
  4. Recovery techniques exist to achieve the population and distribution objectives or can be expected to be developed within a reasonable timeframe.
    The recovery techniques required (see #3 above) are scientifically well-established and can be effective, and so are expected to positively contribute to the survival of the species.

Date of Assessment: November 2003

Common Name (population): Dwarf Hackberry

Scientific Name: Celtis tenuifolia

COSEWIC Status: Threatened

Reason for Designation: A shrub of dry sandy or calcareous alvar woodland habitats found only at six disjunct and fragmented sites adjacent to the Great Lakes. Fewer than 1 000 plants have been documented. Threats include potential loss of habitat due to quarrying operations and sand pit expansion in eastern Ontario sites and significant losses in some years due to beetle infestations.

Canadian Occurrence: Ontario

COSEWIC Status History: Designated Special Concern in April 1985.
Status re-examined and up-listed to Threatened in November 2003. Last assessment based on an updated status report.

* COSEWIC = Committee on the Status of Endangered Wildlife in Canada.

The Dwarf Hackberry is listed as Threatened on Schedule 1 of the Species at Risk Act (SARA). It is considered imperilled in Ontario (S2) and Canada (N2). Although generally secure in the United States (N5) and around the globe (G5), it is less secure in several states: New Jersey (S2), Michigan (S3), North Carolina (S3), Ohio (S3), and Illinois (S3?) (NatureServe 2009). Less than 0.2% of the Dwarf Hackberry’s range is found within Canada (Little 1977).


Report a problem or mistake on this page
Please select all that apply:

Thank you for your help!

You will not receive a reply. For enquiries, contact us.

Date modified: