Is It a Boy or a Girl? Testing Hypotheses to Explain Variable Sex Ratios in Columbian Ground Squirrels

Photo 1. Columbian ground squirrel female with dry grass material collected from the meadow she inhabits, which will line her burrow. Ground females give birth and raise their young in individual nest burrows that they defend against other colony members. Daily field observations allow us to detect identify those capture as first emerge above ground, around time of weaning. credit: Sebastian Sosa, Institut Pluridisciplinaire Hubert Curien, CNRS, France. 2. juvenile busy foraging. Offspring are born naked blind, nursed over a period approximately 27–28 days. They weaned shortly after must rapidly forage gain weight few weeks before hibernation. Our study suggests male offspring costlier produce than females, terms body mass. With more local kin present, mothers best condition biased sex ratio towards males, poor females. Without co-breeding close kin, pattern was reversed, producing daughters, sons. These results suggest combination influences relative maternal matriline dominance on ratio. photographs illustrate article “Parental investment squirrel: empirical tests allocation models” by Thibaut Barra, Vincent A. Viblanc, Claire Saraux, Jan O. Murie, F. Stephen Dobson, published Ecology. https://doi.org/10.1002/ecy.3479