Merging indigenous and scientific knowledge links climate with the growth of a large migratory caribou population

1. Climate change in the Arctic is two to three times faster than anywhere
else in the world. It is therefore crucial to understand the effects of
weather on keystone arctic species, particularly those such as caribou
(Rangifer tarandus) that sustain northern communities. Bridging long-term
scientific and indigenous knowledge offers a promising path to achieve
this goal, as both types of knowledge may complement one another. 2. We
assessed the influence of environmental variables on the spring and fall
body condition of caribou from the Porcupine Caribou Herd. This herd
ranges in the Yukon and Northwest Territories (Canada) and Alaska (USA),
and is the only large North American herd that has not declined since the
2000s. Using observations recorded through an indigenous community-based
monitoring program between 2000-2010, we analyzed temporal trends in
caribou condition and quantified the effects of weather and critical
weather-dependent variables (insect harassment and vegetation growth), on
spring (n = 617 individuals) and fall (n =711) caribou condition. 3. Both
spring and fall body condition improved from 2000 to 2010, despite a
continuous population increase of ca. 3.6% per year. Spring and fall
caribou condition were influenced by weather on the winter and spring
ranges, particularly snow conditions and spring temperatures. Both snow
conditions and spring temperatures improved during our study period,
likely contributing to the observed caribou population increase. Insect
harassment during the previous summer and the frequency of icing events
also influenced caribou condition. 4. Synthesis and applications. Our
study first shows how untangling the relative influences of seasonal
weather variables allows a much better understanding of variation in
seasonal body condition in Rangifer populations. Second, it indicates that
a large migratory caribou population can grow and improve body condition
in a global context of caribou decline and climate warming, thereby
warning against generalizations about the influence of climate on all
Rangifer populations. Finally, it testifies how data from indigenous
community-based monitoring on a large spatiotemporal scale can remarkably
improve ecological understanding of wildlife sustaining human communities.
We recommend that management practices promote indigenous community-based
ecological monitoring whenever feasible.