Scientific Name: Danaus plexippus
Taxonomy Group: Arthropods
Range: Northwest Territories, British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Quebec, New Brunswick, Prince Edward Island, Nova Scotia, Newfoundland and Labrador
Last COSEWIC Assessment: November 2016
Last COSEWIC Designation: Endangered
SARA Status: Schedule 1, Special Concern
Butterfly enthusiasts and citizen scientists are encouraged to submit their Monarch observations using eButterfly. This website allows users to track their butterfly sightings and locations, organize, store and share photos, and make a valuable contribution to science and conservation.
Image of Monarch
The adult Monarch is a bright orange butterfly with heavy black veins and a wide black border containing two rows of white spots. The wingspan is about 10 cm. Males can be distinguished from females by the presence of black coloured scent glands on each of their hind wings. Monarchs can be distinguished from the smaller but similar Viceroy by the absence of an inner margin of black on the hind wings. Monarch larvae or caterpillars are striped yellow, black and white; they grow to about 5 cm in length. The distinctive gold-green chrysalis suspends from a milkweed leaf or branch.
Distribution and Population
The Monarch is widely distributed from Central America to southern Canada, and from coast to coast. There are three populations of the Monarch: western, central, and eastern. The western population includes all Monarchs found west of the Rocky Mountains to the Pacific Coast, from southwestern USA to southern Canada. The entire western population overwinters along the coast of California in Eucalyptus trees (native to Australia, brought to California in the 1850s). The central population occurs in Guatemala, El Salvador, Honduras, Belize, Nicaragua, Costa Rica, Panama, and southern Mexico. This population is relatively sedentary; the butterflies make short seasonal migrations and are reproductively active throughout the year (unlike the butterflies of the other two populations). The eastern population of the Monarch is the largest of the three, and includes all Monarchs that occur east of the Rocky Mountains, from the Gulf coast to southern Canada, and from the Great Plain States and Prairie Provinces east to the Atlantic coast. The entire population overwinters annually at approximately 12 sites in the Transverse Neovolcanic Belt, a mountain range in central Mexico. These sites are located within 800 km of each other and occur in the high-altitude Oyamel Fir forest. The Monarchs arrive at these sites between early November and late December, and form large aggregations of millions of butterflies. Generally, they remain inactive throughout the winter. The mass of butterflies breaks up in March and early April and the Monarchs begin their migration north. They fly to the Gulf Coast where the females lay eggs, and it is these offspring that continue the migration back to the northern breeding range. It takes several generations of butterflies to reach the northern part of the range, each generation responding to the availability of milkweed plants. Presently the eastern population numbers in the tens of millions, while the western population numbers in the millions. However, each population varies dramatically from year to year, depending on the climatic conditions.
Monarchs in Canada exist primarily wherever milkweed (Asclepius) and wildflowers (such as Goldenrod, asters, and Purple Loosestrife) exist. This includes abandoned farmland, along roadsides, and other open spaces where these plants grow. Monarch wintering habitats include Eucalyptus trees along the Californian coast, and the Oyamel Fir forest in central Mexico. The distribution of the Monarch has gradually shifted eastward over the past century, due to a combination of clearing of deciduous forests in the eastern USA and southeastern Canada, and loss of habitat to agricultural development in the Great Plains.
The eastern and western populations of the Monarch annually migrate south, beginning in August and continuing until mid-October. The butterflies actively seek nectar from wildflowers to increase their strength and build up a fat reserve that will maintain them throughout the winter and the early spring (when no nectar is available). Large aggregations of Monarchs may be seen in the fall along the north shores of Lakes Ontario and Erie, as they prepare to cross the open water. There are 2 or 3 generations of Monarchs from June to September each year. Development through the four stages of the life cycle (egg, larva, pupa, adult) may take between 20 and 45 days, depending on the weather conditions. A female may lay up to 400 eggs per fertilization. The pinhead-sized green eggs are laid one by one on leaves of various milkweed species, the primary food of the caterpillars that will hatch from the eggs after 3 to 12 days. When full-grown (which takes 9 to 18 days of serious chewing), the caterpillar attaches itself upside down to a milkweed leaf or branch, and forms a light green pupa. The adult butterfly emerges after a further 9 to 18 days. The adults have a 1:1 sex ratio. Monarch larvae store poison from the milkweed leaves they eat and pass it along to the adults, which makes the butterfly unpalatable and provides some protection against predation.
Environmental conditions and loss of breeding habitat pose threats to all Monarchs. However, there are population-specific threats as well. The eastern population of the Monarch is limited by loss of habitat to logging, human disturbance, and predation, especially while wintering in Mexico. Widespread and increasing use of herbicides in North America is another significant threat, which kills both the milkweed needed by the caterpillars and the nectar-producing wildflowers needed by the adults. Threats for the western population include real estate development along the Californian coast, which infringes on the wintering sites of the western population; programs to actively eliminate the Eucalyptus trees (an exotic species); and a protozoan disease.
Federal ProtectionThe Monarch is protected under the federal Species at Risk Act (SARA). More information about SARA, including how it protects individual species, is available in the Species at Risk Act: A Guide.
The Monarch occurs in Point Pelee National Park in Ontario, where it is protected under the Canada National Parks Act. Point Pelee, as well as Long Point and Prince Edward Point, are designated as Monarch Butterfly Reserves.
Provincial and Territorial Protection
Other Protection or Status
The Monarch Butterfly Conservation Program was created by the Mexican government to conserve wintering grounds for the species as well.
PLEASE NOTE: Not all COSEWIC reports are currently available on the SARA Public Registry. Most of the reports not yet available are status reports for species assessed by COSEWIC prior to May 2002. Other COSEWIC reports not yet available may include those species assessed as Extinct, Data Deficient or Not at Risk. In the meantime, they are available on request from the COSEWIC Secretariat.
13 record(s) found.
- COSEWIC Status Reports (1 record(s) found.)
- COSEWIC Assessments (1 record(s) found.)
- Response Statements (1 record(s) found.)
- Action Plans (6 record(s) found.)
- Management Plans (1 record(s) found.)
- COSEWIC Annual Reports (1 record(s) found.)
- Consultation Documents (1 record(s) found.)
- Recovery Document Posting Plans (1 record(s) found.)
COSEWIC Status Reports
Response Statement - Monarch (2010)This species has a population of millions to over one billion individuals. The most sensitive stage of its annual cycle is overwintering. There are two main overwintering areas: the Oyamel Fir forests of Central Mexico, where 90% of the population overwinters, and coastal regions of California. The overall area of these sites is relatively small, and threats, especially from logging in the Oyamel Fir forests, are sufficient to suggest that the species could become Threatened in the near future.
COSEWIC Annual Reports
COSEWIC Annual Report - 2010 (2010)Under Canada’s Species At Risk Act (SARA), the foremost function of COSEWIC is to “assess the status of each wildlife species considered by COSEWIC to be at risk and, as part of the assessment, identify existing and potential threats to the species”. During the past year, COSEWIC held two Wildlife Species Assessment Meetings and reviewed the status of 79 wildlife species (species, subspecies, populations). During the meeting of November 2009, COSEWIC assessed or reviewed the classification of the status of 28 wildlife species. COSEWIC assessed or reviewed the classification of an additional 51 wildlife species (species, subspecies and populations) during their April 2010 meeting. For species already found on Schedule 1 of SARA, the classification of 32 species was reviewed by COSEWIC and the status of the wildlife species was confirmed to be in the same category (extirpated - no longer found in the wild in Canada but occurring elsewhere, endangered, threatened or of special concern). The wildlife species assessment results for the 2009-2010 reporting period include the following: Extirpated: 6 Endangered: 39 Threatened: 16 Special Concern: 17 Data Deficient: 1 This report transmits to the Minister the status of 46 species newly classified as extirpated, endangered, threatened or of special concern, fulfilling COSEWIC’s obligations under SARA Section 24 and 25. A full detailed summary of the assessment for each species and the reason for the designation can be found in Appendix I of the attached report. Since its inception, COSEWIC has assessed 602 wildlife species in various risk categories, including 262 Endangered, 151 Threatened, 166 Special Concern and 23 Extirpated. In addition, 13 wildlife species have been assessed as Extinct. Also, to date, 46 wildlife species have been identified by COSEWIC as Data Deficient and 166 wildlife species were assessed as Not at Risk. This year has been a particularly productive year for COSEWIC’s Aboriginal Traditional Knowledge (ATK) Subcommittee. In April 2010 COSEWIC approved the Aboriginal Traditional Knowledge Process and Protocol Guidelines, providing clear and agreed principles for the gathering of Aboriginal Traditional Knowledge to carry out COSEWIC functions as required under Section 15(2) of SARA (See Appendix III of the attached report). We are grateful for the rich and enthusiastic contribution made by community elders and experts in helping the ATK Subcommittee prepare the ATK protocols.
Recovery Document Posting Plans
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