Drivers of a temporal change in the adult sex ratio of a Roosevelt elk (Cervus canadensis roosevelti) population

A Roosevelt elk population in Redwood National and State Parks, California, exhibits a female-skewed adult sex ratio (ASR) that declines with increasing population density, providing empirical support for the female substitution hypothesis (FSH). The FSH suggests that as food resources deplete, females outcompete males for forage, leading to passive male displacement. Over 24 years, systematic surveys revealed that declining ASR correlated with rising female abundance and reduced forage biomass, while males were found in peripheral areas when females were abundant. This pattern aligns with the FSH, demonstrating density-dependent effects in a nonmigratory, hunting-protected population.

Espinoza, Z. S., & Weckerly, F. W. (2022). Drivers of a temporal change in the adult sex ratio of a Roosevelt elk (Cervus canadensis roosevelti) population. Journal of Mammalogy, 103(6), 1373–1382. https://doi.org/10.1093/jmammal/gyac075