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The Mystery of Arctic Tern Decline

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Nesting Arctic tern, Nunavut. © Mark Mallory

Inuit knowledge and ecological science provide complementary insights

Inuit from Kuujjuarapik, Nunavik, have observed a decline in Arctic tern numbers nesting on islands in southeastern Hudson Bay, starting in the early 2000s. These observations are consistent with reports from other regions. But what has caused this decline remains unclear. Our team of Inuit and scientists tries to shed light on this question. 

“Takatakiaq, takatakiaq,” that’s the sound Arctic terns make. It’s also their name in Inuktitut. These majestic grey and white plumaged birds, with a black crown to their head, are small but mighty. They make the longest annual migration of any species on Earth. After wintering near Antarctica, they migrate to the Arctic where they breed, an important moment for Inuit who collect their eggs for subsistence. 

Decades of Inuit observations 

Inuit harvesters, who visit Arctic tern colonies every summer, have observed terns over longer periods and with a greater regularity than researchers typically can. Recognizing the value in this, our team of scientists has worked in close collaboration with Inuit providing a great opportunity to better understand what is happening to Arctic terns. 

Arctic tern eggs, Sleeper Islands, Nunavut. © Kirsten Wilcox

“Arctic terns are extremely difficult to study. They nest in remote places scattered on small islands where many other birds don’t, so it’s hard to generate the resources to go study them,” explains Grant Gilchrist from Environment and Climate Change Canada, one of the seabird specialists involved in the project. 

In Kuujjuarapik, a community located in southeastern Hudson Bay in Nunavik, egg picking takes place during a two-week period at the beginning of July. This activity contributes to community well-being because people are out on the land, working together, and sharing eggs with family and friends. In 2018 and 2019, we conducted interviews with Inuit harvesters and Elders to gather their knowledge on the ecology, distribution and abundance trends of Arctic terns around the community. 

It was particularly exciting to discover that Arctic terns were able to lay new eggs to replace the ones that were picked or depredated. We also learned things that we were not expecting, like the fact that Inuit harvesters use Arctic terns as indicators of environmental conditions and wildlife presence. Regrettably, this culturally important species is declining, and we are not sure why. 

Possible causes of decline 

Many harvesters from Kuujjuarapik agreed: Arctic terns are declining around their community. Consistently abundant between the 1970s and the 1990s, these birds started to decline locally in the early 2000s. 

“Overharvesting seems to be one of the causes of the decline in the population around Kuujjuarapik,” says one harvester. “The decline, I think it is all over. Not by over harvesting, but something else?” further explains Lucassie Arragutainaq from the Hunters and Trappers Organization of Sanikiluaq, Nunavut. Sanikiluaq is a community located on the Belcher Islands, approximately 160 km northwest of Kuujjuarapik. Other possible causes of decline reported by Kuujjuarapik residents include nest disturbance and predation, desertion of tern nesting areas due to isostatic rebound, climate change, cyclical abundance variations and a decline in Arctic tern main prey, the capelin. 

“Some of the factors driving this decline likely don’t occur in the Canadian North but in the southern hemisphere,” adds Grant Gilchrist. Using ultralight tracking devices, seabird biologists are now able to track terns throughout their full migratory cycle in an attempt to understand why they may be declining beyond the areas routinely observed by Inuit harvesters. 

“This co-development of knowledge — with Inuit providing regional, local experience over long time periods and the scientists using new technologies to track their global migration — is providing completely new insights on Arctic tern migration, distribution and trends, which none of us knew about. That’s a great story,” says Grant Gilchrist enthusiastically. 

Arctic tern predators (upper part) and prey (lower part) identified by Inuit contributors. The dotted arrow identifies a new predator. Species in the rectangle are those identified as potential prey for young Arctic terns. Originally published in: Henri DA et al. (2020) PLoS ONE 15(11): e0242193. © Frankie Jean-Gagnon

Next step: community-based monitoring of Arctic terns 

In summer 2021, motivated by one of the recommendations made by Kuujjuarapik harvesters, we extended the project to conduct community-based monitoring of Arctic terns, gulls and common eider ducks in the Belcher and Sleeper Islands. This time, the bird surveys were entirely led by a team of 25 Inuit. “We just sent one scientist to join the team and help with data collection,” adds Grant. 

Following the success of this first field season, we plan to repeat it in summer 2022. “We are now working to expand this type of collaborative work with communities in Hudson Strait,” explains Dominique Henri from Environment and Climate Change, who leads the team that is gathering and documenting knowledge and ecological observations from Inuit harvesters. 

By braiding together multiple ways of knowing and expanding our study to more communities, we are slowly shedding light on the mystery of Arctic tern decline. 

This project was conducted as a partnership between Environment and Climate Change Canada, the Nunavik Marine Region Wildlife Board, the Local Nunavimmi Umajulivijiit Katujiqatigininga (LNUK) of Kuujjuarapik and Acadia University. 

Source: Henri DA, Martinez-Levasseur LM, Weetaltuk S, Mallory ML, Gilchrist HG, Jean-Gagnon F. (2020) Inuit knowledge of Arctic Terns (Sterna paradisaea) and perspectives on declining abundance in southeastern Hudson Bay, Canada. PLOS ONE 15(11): e0242193. The original research study is available at: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0242193

VIALaura M. Martinez‐Levasseur
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