The birds and the trees: Quantifying the drivers of whitebark pine decline and Clark's nutcracker habitat use in Glacier National Park
Kovalenko V. 2023. The birds and the trees: Quantifying the drivers of whitebark pine decline and Clark's nutcracker habitat use in Glacier National Park. University of Montana
Whitebark pine (Pinus albicaulis), recently listed as threatened under the Endangered Species Act, is in steep decline in Glacier National Park, Montana, USA due to the non-native pathogen Cronartium ribicola, causal agent of the fatal disease white pine blister rust. A sample of the park’s population suggests that approximately 70 percent of whitebark pines have died, while 65 percent of the remaining trees are infected. Using landscape and climate variables, we show how geographic location, elevation, aspect, solar radiation, relative humidity, and snowpack interact with tree diameter to affect mortality, disease incidence, cone production, and regeneration. We also examine how these stand characteristics affect the habitat use of whitebark pine’s mutualist seed disperser, the Clark’s nutcracker (Nucifraga columbiana). Using in-person point counts, acoustic recording units, and satellite-tracked nutcrackers, we elucidate the factors that are important to nutcracker habitat selection and show how distinct survey and modeling techniques compare in determining their relative importance.