Non-random distribution of ungulate salt licks relative to distance from North American oceanic margins

Aim: Terrestrial deposition of aerosol marine sodium declines with distance from coastlines. Salt deprivation in vertebrate herbivores and salt-seeking behaviors should hence increase with distance inland. We analyze published geospatial data on ungulate-patronized salt licks to test whether they are non-randomly distributed relative to distance from oceans and elevation.

Location: Canada, Alaska, and the contiguous United States.

Taxon: Cetartiodactyla (even-toed ungulates).

Methods: We determined the land area and median elevation of 100 km increments from the North American coast. The null model of the expected number of licks within each interval was determined by the ratio of the interval’s land area to the total land area, multiplied by the total number of licks. We asked whether the number of licks further from coastlines was significantly higher than chance. We also assessed whether licks occur disproportionately at higher elevations, comparing the median elevation of ...