Place-based knowledge enriches our understanding of biodiversity change

On the remote islands of Yáláƛi, the Goose Island Archipelago, on the Central Coast of British Columbia, the composition of birds singing their forest melodies has changed over the last seven decades. Once, these forests echoed primarily with the musical trills of Dark-eyed Juncos, the vibrating warble of Orange-crowned Warblers, and the metallic calls of Red Crossbills. Today, although these species are still present, a recent study found that the composition of forest bird species is relatively more even.¹

It’s rare, in ecology, to have access to historical datasets. Some local examples include the Mountain Legacy Project, which houses historical photographs of mountains in Western Canada dating back to 1888, or the century-old salmon scale archives that were used to track life-history diversity in Skeena Pacific salmon. While historical comparisons are rare in western science, Indigenous knowledge systems have done this for millennia. In many ways, western science is “a curious little sister on this coast”, and weaving Indigenous ways of knowing, local knowledge, and western science can deepen our understanding of ecological change.

Map of Yáláƛi, the Goose Island Archipelago, where the study took place.

Yáláƛi is both a cultural and ecological hotspot. This temperate rainforest archipelago has been important to both birds and to the Haíɫzaqv since time immemorial. As a federally recognized Important Bird Area, it hosts a rich diversity of both marine and terrestrial species. As the site of historic Haíɫzaqv villages and present use, it is also rich in culture.

Even up until the 1930s, the entire nearby village of Wágļísļa would relocate to the main island, Goose Island, for the summer, bringing everything with them. The biodiversity of life on and around Goose Island was part of what made this area so special. According to a Heiltsuk Traditional Use Study conducted with community Elders in the 1990s, and maintained by the Heiltsuk Integrated Resource Management Department (HIRMD), the island and the surrounding waters were once – and still remain – a harvesting ground for many culturally important species, including seaweed, geese, ducks, deer, halibut, and cod.

Old hunting cabin nestled in the forest, with Heiltsuk art on the front, near the lagoon on Goose Island. — Old hunting cabin near the lagoon on Goose Island. Photo by Chris Darimont.

Increasing marine traffic in the territory due to natural resource extraction is a huge threat to both the ecosystems in the area and to the food sovereignty of the Haíɫzaqv People, which are intricately connected. This study originally came about in response to a pipeline project that was proposed in the mid-2000s. While the pipeline in question was never built, a major diesel spill in Seaforth Channel at Q̓vúqvái (Gale Creek) in 2016, and a close call in 2017 when a fuel barge nearly ran aground onto the Gosling rocks during a storm, made it clear that it is crucial to have detailed baseline biodiversity data for this area.

In 1948, a taxidermist and biologist from Saskatchewan by the name of Charles Guiguet spent an entire summer at Yáláƛi on behalf of the Royal BC Museum. Although he wasn’t here by invitation or permission of the Heiltsuk, the dataset he collected provides a unique opportunity to look at how bird communities have changed since then.

Our research team used Guiguet’s data as a baseline, and compared it with bird surveys conducted by the Haíɫzaqv-led monitoring and stewardship initiative called CoastWatch in 2010, as well as surveys completed by Simon Fraser University researchers in 2011 and 2015. We also used data accessed from a modern citizen science platform called eBird, where observers can upload detections of bird species from around the globe.

In black and white, Charles Guiguet prepares a porcupine specimen sitting at a wood table, in Tweedsmuir Provincial Park, near Stuie, British Columbia. — Charles Guiguet prepares a porcupine specimen in Tweedsmuir Provincial Park, near Stuie, British Columbia. 16 September 1938. B.C. Archives, Province of British Columbia, photo number 6-03674.

We found that bird communities have changed.

Read this new open access journal article in Ecology and Evolution .

For example, Guiguet found only one warbler species. This is a striking finding, because in the present day, at least five additional species are present, two of which are very common. We also found a far higher proportion of thrushes in the contemporary period, particularly American Robins, Hermit Thrushes, and Varied Thrushes. In Guiguet’s time, Orange-crowned Warblers, Dark-eyed Juncos, and Red Crossbills made up over 55% of all birds he recorded. Today, there is no clear “Top 3”.

But why have these distributions shifted so much?

The speculated driving forces of bird community change are diverse. First, there have been big changes in the mammal communities on Yáláƛi, from the arrival of deer (and subsequently Goose Island’s famous coastal wolves), to smaller mammals like river otters and mink. These animals can have a drastic influence on island vegetation and bird habitat.

A close up of a Western Flycatcher (Empidonax difficilis), resting on a branch in a brightly lit forest scene. — Western Flycatcher (Empidonax difficilis). Photo by John Reynolds.

An Orange-crowned warbler (Leiothlypis celata) looks regal, and mostly yellow, perched on a branch. — Orange-crowned warbler (Leiothlypis celata). Photo by John Reynolds.

Second, human activity has changed. Not only has declining deer abundance in recent years meant that Haíɫzaqv hunters aren’t frequenting the island as much, but the increased length of time since European colonization has meant that the impacts on bird communities of a larger Haíɫzaqv population is further in the past.

Lastly, a tsunami in 1964 altered the physical landscape by removing the sandy, shorebird friendly substrate in the large lagoon.

Birds can give us a lot of insight into changes happening in ecological communities, both because they are easy to survey, and because they are sensitive to change. Understanding how bird communities change over time can give us insights into how other constituents of their habitats are changing, which can help us plan and adapt our conservation strategies.

By weaving Western science with Indigenous knowledge, we deepen our understanding of community change by integrating long-standing, place-based knowledge of ecosystems with new data. This will be especially important as we witness increasingly rapid ecological change in the face of climate change.

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