These beautiful butterflies, with orange wings contrasted with a lattice of black, are the only butterflies that make an incredible annual migration from Canada and the north of the US to Mexico and California in the autumn. For some it will be a one-way trip, with females laying eggs on route back then dying, with their offspring continuing the process, ‘leapfrogging’ their way back.
The Xerces Society, an international conservation group, conducted their annual butterfly count In January 2021, and say the results aren’t good. Data collected at 246 sites showed less than 2000 overwintered in California, a 99.9% drop since the 80’s. In the 2020 count, in the town of Pacific Grove none were spotted, whereas 28,000 were seen in 2006. East of the Rockies apparently had 80% fewer compared to the mid-1990’s.
Protected status has been requested from the US Fish and Wildlife Service, but after a four-year assessment, they say that listing the monarch under the Endangered Species Act is warranted, but lack the money/ resources to protect the species, despite meeting the criteria.
Conservationists are concerned by the diminishing numbers of these butterflies, and the reasons are complex. Change of habitat is one – forests in Mexico are being destroyed, freak weather caused by climate changes is another, but the main reason is the lack of food. Monarchs rely on Tropical Milkweed (Asclepias curassavica) but because crops are being sprayed with herbicides, the Milkweed is probably being killed off in the process. The second biggest threat is a disease known as OE, and infected butterflies inadvertently spread the spores over the Milkweed, and this weakens them, cripples their wing formation and they become unable to emerge from their chrysalises.
So what about a breeding plan? Well, there seems to be a fine line here – are we helping or hurting monarchs by releasing large numbers of captive reared monarchs? In the US people are purchasing monarchs for release at weddings, etc, and because of their decline, others are rearing large numbers in ‘backyard’ environments or buying from breeders and releasing them, which unfortunately encourages the butterflies to remain where the food source is available, and become non-migratory. Mass rearing conditions can cause crowding and the spread of disease, cause the loss of genetic diversity, or can interfere with monitoring programmes. Even those reared in the most sterile ‘hospital’ conditions sometimes experience outbreaks of harmful diseases.
Monarchs are not a native species to Portugal but are here, perhaps having been blown here originally from the US, and are mostly recorded as a sporadic migrant in small numbers in Europe, possibly from resident populations in the Canary Islands. They can also be found in some Pacific islands, Australia, New Zealand, some places in Asia and the Azores, Madeira, Canary Islands and southern Spain.
According to my colleague, published and knowledgeable butterfly expert, Steve Andrews – Portugal’s very own ‘Butterfly Guy’ - monarchs can also exist on a plant called the Bristly-fruited Silkweed (Gomphocarpus fruticosus), and the only reason they have been able to establish breeding colonies in southern Portugal is because this has become naturalised in many places. This plant, which is closely related to the milkweeds, has curious inflated seed-pods and is often grown in gardens for its ornamental qualities. A complex detailed survey was carried out in Portugal in 2008 to count monarchs in a specific area to determine the population size, carried out throughout the year, which showed that there was a decrease in the population of adults and also of eggs and caterpillars in the survey period.
Steve informs me that he has been rearing and releasing monarchs for some while. He is encouraging friends and colleagues to help, by planting the food-plant seeds, and has even himself managed to keep larvae alive in plastic bottles, where they are safe from predators, mostly wasps, who will eat the caterpillars and even the butterflies before they have managed to take their first flight, so if you would like to help stop these beautiful creatures dying out completely, contact Steve Andrews on Facebook for details on where to get caterpillars and seeds.