Canada, Mexico and the USA have recently teamed up to restore dwindling Monarch butterfly populations. The ingenious solution is to create a 1500-mile ‘flyway’ to assist the butterflies on their incredible annual migration.
The flyway will consist of cultivated milkweed plants along the route of Interstate Highway 35. The I-35 was chosen because it runs roughly along the route of Monarch migration, and its federal status means that agencies will be able to more effectively coordinate conservation efforts.
The annual migration of Danaus plexippus is the second longest of all insect species, taking them from their over-wintering sites in northern Mexico, through Texas and the Midwest, up to the southern tip of Canada. The butterflies that arrive back are the great-grandchildren of those that first set off.
Tragically, Monarch populations have fallen dramatically in the past twenty years. Conservationists measure their population by the size of the over-wintering site, with an estimated 50 million Monarchs per hectare. In the peak of 2004 they occupied 18.19 hectares. In 2014: a mere 0.67 hectares.
This drastic fall is largely attributed to the loss of milkweed in the Midwest where Monarchs lay their eggs. The use of GM herbicide-resistant Corn and Soybean has caused herbicide to be used more widely, killing the milkweed that previously thrived in hedgerows and at the edge of fields.
Furthermore, Monarchs migrate because they cannot survive well in severe weather. With populations so low, an extreme drought or heavy rainfall could completely wipe out the few that remain. Anthropogenic climate change has caused these extreme weather events to become more prevalent, making the need for a ‘flyway’ ever more urgent.
In early 2016 populations did bounce back to 150 million. However this was attributed to favourable weather the previous winter. For this population growth to be sustained and reliable, Federal support was needed: previous efforts by the US Fish and Wildlife Service were enough to restore only 1% of the lost habitat.
Now that conservation is a Federal initiative more resources are available, and a clear path can be created for the Monarchs along their migratory route. The target is to restore populations to the 20 year average of 225 million.
‘Wildlife corridors’ have been used elsewhere with great success. For example in India there are 88 ‘corridors’ allowing elephants to travel between protected areas. In a travel solution of a different kind, roads are to be painted bright colours in Iceland in order to deter Arctic Terns from wandering on them and getting hit by traffic.
We are currently experiencing a rate of species extinction 1000x greater than the background rate. With any luck, the Monarch’s story will set the precedent for Federal attention to be focused on conservation of threatened species – not just those that are lucky enough to be an iconic pollinator.