Impact of Tundra Fires on Bird Species Diversity in Lakes of the Yukon-Kuskokwim Delta

Under a rapidly warming climate, wildfires have become increasingly frequent in the Arctic tundra. Wildfires can influence the physical and chemical makeup of the ecosystem in which they occur, and they can also impact nearby water bodies through the movement of nutrients across the landscape. Post-fire changes in vegetation composition and ground thaw can also lead to long-term shifts in ecosystem structure in terrestrial and aquatic ecosystems. Birds are often used as ecosystem indicators for landscape changes. A significant change in bird biodiversity following a fire could indicate differences in ecological resources. While attention has been given to the impacts of fire on birds in terrestrial tundra landscapes, the impact of fires on species diversity of birds within and adjacent to aquatic ecosystems is currently understudied. Over two weeks in July 2022, we conducted point count surveys across 21 lakes in the Yukon-Kuskokwim Delta of Alaska to assess bird biodiversity. Surveyed lakes were located in areas that burned in 1972 (n= 7) and in 2015 (n= 7), and in adjacent unburned areas (n= 7). We counted a total of 221 birds and 25 species across all surveys. Lakes in the 1972 burn had the highest species richness (21 bird species) followed by the 2015 burn (16 bird species) and finally the unburned (15 bird species). The average number of species per lake was highest in the 1972 burn region (7.1); followed by lakes in the unburned tundra (5.3), and 2015 burn (4.3). However, there were more species that were unique to lakes in the 2015 burn (i.e., beta diversity; 2.7) ), followed by the 1972 burn (1.9), and lastly by the unburned lakes (1.8). Our results suggest that tundra fires increase the diversity and dissimilarity of birds in and adjacent to lakes, an important consideration for the rapidly changing Arctic ecosystem.