Demographic Effects of a Megafire on a Declining Prairie Grouse in the Mixed‐grass Prairie

Recent studies have documented benefits of small, prescribed fire and wildfire for grassland-dependent wildlife, such as lesser prairie-chickens (Tympanuchus pallidicintus), but wildlife demographic response to the scale and intensity of megafire (wildfire > 40,000 ha) in modern, fragmented grasslands remains unknown. Limited available grassland habitat makes it imperative to understand if increasing frequency of mega-fires could further reduce already declining lesser prairie-chicken populations, or if historical evolutionary interactions with fire make lesser prairie-chickens resilient. To evaluate lesser prairie-chicken demographic response to megafires, we compared lek counts, nest density, and survival rates of adults, nests, and chicks before (2014-2016) and after (2018-2020) a 2017 megafire in the mixed-grass prairie of Kansas, USA (Starbuck fire similar to 254,000 ha). There was a 67% decline in attending males on leks post-fire and a 57% decline in occupied leks post--fire. Despite population declines as indicated by lek counts, adult female breeding season survival ((S) over cap) was similar pre-((S) over cap = 0.65 +/- 0.08 [SE]) and post-fire (0.61 +/- 0.08), as was chick survival (pre-fire: 0.23 +/- 0.07; post-fire: 0.27 +/- 0.11). Nest survival appeared lower post-fire (pre-fire: 0.38 +/- 0.06; post-fire: 0.20 +/- 0.06), but did not differ at the 95% confidence interval. Nest density of marked females declined 73% in areas burned by megafire. Although lesser prairie-chickens persisted in the study area and we documented minimal effects on most demographic rates, reduced lesser prairie-chicken abundance and reproductive output suggests full recovery may take >3 years. Increased propensity for megafire resulting from suppression of smaller fires, compounded by climate change and woody encroachment, may impose a short-term (3-5 year) threat to already declining lesser prairie-chicken populations.