Conservation Biology and the Quest to Save the Monarchs

Conservation biology is not a career choice for the faint of heart. Making decisions about the conservation of species, habitats, or ecological systems is complex and we are always working with incomplete information. Yet difficult choices must be made as we try to conserve the great variety of life on Earth. How do we meet the urgency of conservation needs in times of competing societal needs, data shortages, and financial limitations?

Science and Conservation: A Balancing Act

As a scientist, I fervently believe that our conservation plans should be developed with reference to the best available data and rigorous application of the scientific method.

To be effective in conservation, we must:

• Apply the best available data and scientific method.
• Build public confidence in the scientific process.
• Acknowledge the limitations of data and ecological complexity.
• Balance scientific findings with societal and financial factors.

Conservation isn’t just about biology; it’s about people, politics, and economics.

The Challenge: Monarch Butterfly Conservation

A Complex Life Cycle

Monarch butterflies provide a case study in the challenges of conservation planning. First, monarchs have a complicated life history, with migratory and non-migratory generations, periods of sexual inactivity, and a very wide geographic distribution of breeding sites. Getting robust scientific data for all parts of the monarch lifecycle in all parts of their range is an enormous challenge.

Ecological Interactions

Monarchs are embedded within complex ecological systems. They face predators and parasites that attack them, host plants that vary in nutritional and medicinal quality, weather patterns that differentially influence monarchs, their enemies, and their host plants, and a climate that is changing rapidly. In complex systems like this, indirect effects can be more powerful than direct effects (See Figure 1 for an example). Calculating the magnitude of indirect effects is a perennial problem in ecological systems, but getting the answer right matters for conservation planning.

Human Impact

Monarch populations are influenced by human activities on the landscape, with those activities influenced by cultural, societal, and financial imperatives. Examples of human activities that influence monarch populations include farming practices in the summer breeding grounds and forestry practices in the overwintering grounds.

Research Spotlight: Davis, Croy & Snyder (2024)

The multitude of factors influencing monarch populations has generated controversy in the causes of monarch declines and the appropriate actions to take to conserve them. I was reminded of this recently when colleagues of mine from the University of Georgia published a high-profile paper (Davis et al. 2024) on monarchs. In the paper, they suggest that overwintering declines in monarchs are best explained by declines in the size of monarch butterfly “roosts” during fall migration. To summarize, migration roost sizes have declined by as much as 80%, with higher losses further south, suggesting that overwintering declines in Mexico result from migration failures. To support monarch conservation, they suggest we should provide more resources (nectar plants) for migrating butterflies in the fall and avoid attracting monarchs to non-native milkweeds that artificially extend the breeding season.

Multiple Approaches to Monarch Conservation

Conservation requires diverse strategies. Here’s how we can make a difference:

• Support migration by planting native nectar plants along migration routes.
• Regulate pesticides to reduce harmful effects on monarch habitats.
• Invest in sustainable forestry initiatives near overwintering sites.

Nectar alone won’t help if monarchs lack safe overwintering sites. Conservation efforts must address the entire lifecycle.

The Role of Forests for Monarchs & Mexico

Let’s be clear – there is no single “silver bullet” to prevent monarch declines. Multiple approaches that target vulnerabilities throughout the monarch lifecycle have merit so long as they are based on good data and recognize societal needs and financial constraints. We must also be willing to look into the future, beyond historical data, to consider likely scenarios based on climate models. Pioneers like Dr. Cuauhtemoc Saenz-Romero, who is establishing new oyamel fir sites at higher elevations near Mexico City, are working toward sustainable overwintering sites for monarch butterflies that will live under a future climate. That effort may have no perceivable impact in the short-term but may ultimately save migratory monarch populations from extirpation.

The tree-planting program of Forests for Monarchs remains a key component in an integrated conservation plan for monarch butterflies. Ours is not the only program that matters. But without a sustainable forestry industry that supports native communities near the monarch overwintering habitat, current overwintering sites are doomed. Without them, the iconic migration of monarch butterflies will be lost forever.