Sex differences in a large herbivore’s salt water drinking behaviour: a method for applying a female-biased attractant

Female abundance, which is directly related to population dynamics through recruitment, is crucial for population management, and female culling is an effective means of reducing populations. This study identified a method to preferentially attract females of a large herbivore based on sex differences in mineral requirements, with the aim of facilitating female culling. Given that female sika deer ( Cervus nippon ) experience greater sodium deficiency than males, we attempted to attract female deer using salt water. Containers filled with salt water (with water used as a control) were placed in a forest, and the numbers of occasions on which the adult deer drank from each container were counted. A total of 80 drinking occasions by adult deer were recorded, and 82.5% was drinking of salt water by female deer. Although females clearly preferred salt water to water, no such preference was seen in males. This indicates that salt water is an effective attractant that can promote female-biased culling of sika deer. The identification of minerals in which females tend to be deficient and use thereof for attraction may be beneficial for female-biased culling in a variety of herbivores. Our approach could serve as an efficient female-biased culling method to address declining herbivore populations.