A group of Ottawa researchers is looking at how the drought-like conditions of the past couple of months have affected nectar that monarch butterflies use as fuel for their yearly migration south.

Ottawa

Monarch butterflies, already classified as endangered, may be facing increased risks due to recent extreme heat and drought conditions in Ottawa. Researchers from the University of Ottawa are investigating how these weather patterns are impacting the nectar that monarchs rely on for their migration to Mexico. 

Experiments using mini greenhouses to simulate warmer climates have shown that drought can make nectar thicker and more difficult for butterflies to consume, while also reducing the number of available flowers. The researchers are monitoring the butterflies' weight and fat reserves to assess the quality of nectar, and early findings indicate that these environmental changes could further threaten monarch populations.

Monarch butterflies could be at further risk after hot, dry summer

The monarch butterfly relies on nectar from plants as fuel for its fall migration to Mexico. But a group of Ottawa researchers say this summer's intense heat and drought conditions could be putting this endangered species at further risk. Climate change is increasingly on a radar for how it's affecting monarchs. And so, again, with a year like this, it has the potential to really decline or decrease the number of monarchs that are making it to Mexico and then consequently the ones that will come back. But again, it's been really hard to figure out all the different ways that climate change can influence monarchs because it's such a complex issue. At a farm near Armprior, monarchs fly from flower to flower sucking nectar. Researchers from the University of Ottawa are experimenting on five plant species in an open field to see how the nectar fares under warmer temperatures. They place netted cages around pairs of plants of the same species and then enclose one of those plants in a mini greenhouse. So tell me what's happening to these goldenrod flowers right now. So they're sitting in our warming chamber, our open top chamber, and what's happening is we hope they're experiencing a slight degree of warming that replicates local climate change. The researchers explain that temperatures in the mini greenhouses rose to 50 degrees during one of this summer's heat waves. They say they've already detected changes. The drought has caused the nectar to be thicker and that can create problems for monarchs as they try to get the nectar out with their proboscis. If it's too thick, it's sort of like if you ever tried to drink a milkshake with a small straw, it's really difficult to get out. Over the course of the weeks, the monarchs are placed in cages to feed on the nectar. What is the monarch's response? How can you tell if the quality is good or bad? Yeah, so the main way that we can tell is by their weight. So we weigh them, the ones we have here, on the first, third, and fifth day of their stay in our little monarch hotel that we sometimes like to call it. So we'll be able to see their weight change over the course of those five days. And if the quality is really good, then they'll tend to gain weight and fat reserves. If it's not very good, then they won't have the same amount of fat. So they go through a fat analysis at the end of the experiment, and that's what really helps us tell what kind of quality nectar we're dealing with for each given species. They also extract nectar from the flowers to measure how much sugar is present. But nectar aside, the lack of rain this summer has added another layer of complexity. So far, there's a combination of things. One, it's entirely killed off some of the plants that we've been considering. So in that sense, there is no food from those plants available. There are no flowers. But from the flowers that we still have available, it looks like the sugar and the nectar, the sucrose, is getting to be more concentrated and more difficult to pick up. And so right now we're looking to see how monarchs are going to respond to those flowers that have been under these drought conditions. From the experiment, the researchers took five monarch butterflies from the area and from them bred another 300. The experiment ends on September 15th, and some of the monarch butterflies will be released after that. Jaden Dill, CBC News, near Armprior.

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Breakdown