Linking projections from species distribution models and management in Indigenous communities

Islands are often nature's most delicate laboratories, where unique species evolve in isolation, shielded from the predators and competitors that roam the mainland. When humans accidentally or intentionally bring new animals to these isolated places, the results can be devastating. The newcomers, freed from their natural enemies, often multiply quickly and push out the native life that has lived there for thousands of years. To stop this, scientists use computer models that look at weather, water, and terrain to guess where a new species might go next. These predictions are powerful tools, but they often fail to account for the people living on the land. A model might say a frog will spread everywhere, but it cannot tell if the local community wants to kill the frog, or if they believe the frog belongs there. The most effective conservation plans must bridge the gap between what the computer predicts and what the people value.

This challenge played out on Haida Gwaii, a remote archipelago off the coast of British Columbia, Canada. For centuries, this place has been the ancestral home of the Haida Nation, a people with a deep spiritual and practical connection to their land. The islands are home to only one native amphibian, the Western toad. In 2002, a new species appeared: the northern red-legged frog. Native to the Pacific Northwest mainland, this frog was not supposed to be there. Since its discovery, it has spread rapidly across the largest island in the archipelago, Graham Island. Researchers set out to understand how fast this frog was moving, whether humans were helping it cross the saltwater channels that separate the islands, and how a changing climate might alter its future. But they did not stop at the data. They worked closely with the Haida Nation to see how these scientific predictions could fit into a management plan that respected Haida values, history, and responsibilities.

The team combined old survey records with new fieldwork to map the frog's journey. They found that in just fifteen years, from 2002 to 2017, the frog's territory grew fifteen times larger. By 2017, these frogs occupied about 24 percent of Graham Island. They were moving at an average speed of nearly two kilometers every year. This rate of spread was fast, but not impossible for a frog to achieve on its own. However, the pattern of their movement told a different story. The frogs had crossed a deep, fast-flowing saltwater channel called Masset Inlet to reach a point on the western side of the island. Frogs generally cannot survive long in saltwater, and the distance was too great for them to swim. The researchers concluded that humans had likely carried the frogs across the water, perhaps in boats or on equipment. This human assistance meant the frogs could appear in new places much faster than natural movement would allow.

Using this speed of spread and computer models of the climate, the team looked into the future. They projected that if nothing stopped them, the frogs would cover most of Graham Island by 2040. If humans continued to help them cross the water to the southern island, Moresby Island, the frogs could reach the entire archipelago by 2081. This is a significant concern because Moresby Island contains Gwaii Haanas National Park Reserve and Haida Heritage Site, areas of immense ecological and cultural importance. The models also showed that climate change would likely make more of the islands suitable for the frogs. While some areas might become less hospitable in the very long term, the overall trend suggested that the frogs would find more places to live as the climate warmed, particularly in the lowlands and wet areas.

The scientific data painted a clear picture of a rapid invasion, but the path forward was not simple. When the researchers spoke with the Haida Nation and local community members, they found that the standard solution of eradicating the frogs was deeply problematic. Many people on the islands did not realize the frogs were non-native; they had grown up with them and associated them with positive childhood memories. In Haida culture, frogs hold a special place in oral histories and art, and there is a strong ethic of respect for all living beings. Killing the frogs felt wrong to many, especially since there was no way to use the animals for food or other purposes, which is often a requirement for culling invasive species in the community. Furthermore, the resources needed to remove every frog from thousands of wetlands were simply not available, as the community faced other pressing needs like housing and economic development.

Instead of a battle to wipe out the frogs, the engagement with the Haida Nation pointed toward a different strategy: prevention and education. The researchers realized that the most effective way to protect the islands was to stop humans from accidentally carrying the frogs to the uninvaded southern island, Moresby. This meant focusing on public awareness, teaching people how to identify the frogs correctly, and ensuring that boats and gear were clean before crossing the water channels. The computer models, which once seemed to demand a total war on the species, were reinterpreted as a tool to protect specific, high-value areas. The goal shifted from eliminating the frog to managing its spread in a way that honored the community's values and responsibilities.

This study illustrates that science does not operate in a vacuum. The numbers showing the frogs' speed and the maps showing their future range were accurate, but they were only part of the story. The true solution emerged only when the scientists listened to the people who live on the land. By combining the hard data of the invasion with the cultural wisdom and practical realities of the Haida Nation, the researchers found a path that was both scientifically sound and socially acceptable. The work suggests that the best way to manage invasive species is not just to predict where they will go, but to understand who they are going to affect and how those people want to care for their home.