Monarch Butterflies in Northern California Defy Odds by Breeding in Winter, A New Survival Strategy

As the world grapples with the challenges of climate change, Monarch butterflies in Northern California are adapting in an unexpected way – by breeding in the winter. A recent study published in the Journal of the Lepidopterists' Society has shed light on this new survival strategy, which could be key to the survival of the iconic insect.

The Study's Findings

The research, led by David James, an associate professor of entomology at Washington State University, found that monarch pupae that developed at an urban site in the San Francisco Bay Area during the winter of 2021/2022 had a survival rate of around 50%. This is a significant discovery, as it shows that the butterflies are able to adapt to new environmental circumstances.

A Shift in Breeding Patterns

Over the past five years, overwintering populations of monarchs on the California coast have seen dramatic fluctuations. However, there has been a substantial increase in winter-breeding monarchs that feed on non-native milkweeds in the urban Bay Area. This shift in breeding patterns could be a key factor in the survival of the species.

The Viability of Monarch Pupae

The study, which monitored over 100 wild monarch pupae at the Googleplex campus near Palo Alto during the winter of 2021/2022, found a 49.4% success rate in pupal eclosion, the process of emerging as an adult butterfly. This is promising, given that winter is a sub-optimal environment for breeding.

Implications for Conservation

The rise of winter-breeding monarchs signals a potential adaptation to warmer winters and offers an alternative to the traditional overwintering of non-breeding butterflies at sites in places like Pacific Grove, Santa Cruz, and Pismo Beach. To support this new behavior, conservation practices may need to be adjusted. For example, the timing of pruning the monarch's major source of food, non-native milkweed, could be shifted to late summer to support healthier winter-breeding populations.

Detecting Parasite Infection

The study also explored using exuviae, the shed-skin of the pupae, to detect the presence of the parasite Ophryocystis elektroscirrha. The analysis suggested that around 70% of the winter breeding population was likely infected with the parasite, highlighting the need for further research into its impact and that of other stressors on western monarch populations under natural conditions.

Frequently Asked Questions

Q: What is the significance of monarch butterflies breeding in winter?

A: Monarch butterflies breeding in winter is a new survival strategy that could be key to the survival of the species. It shows that the butterflies are able to adapt to new environmental circumstances, such as warmer winters.

Q: How does the study's findings impact conservation efforts?

A: The study's findings suggest that conservation practices may need to be adjusted to support winter-breeding monarchs. For example, the timing of pruning non-native milkweed could be shifted to late summer to support healthier winter-breeding populations.

Q: What is the next step in this research?

A: The researchers plan to continue monitoring winter breeding monarch populations in the south Bay Area to gather more data. They hope that these monarchs will play an important role in ensuring the sustainability of the nation's western monarch population.

Conclusion

The discovery of monarch butterflies breeding in winter is a significant development in the study of these iconic insects. As the world grapples with the challenges of climate change, it is heartening to see that these butterflies are adapting and evolving to new environmental circumstances. This new survival strategy could be key to the survival of the species, and it is up to us to support and conserve these magnificent creatures.