Tule elk (Cervus canadensis nannodes) – a subspecies of North American elk – are endemic to California. Suisun Marsh, which consists of brackish water tidal and managed wetlands, supports a herd of approximately 280 tule elk. However, increasing salinities, due to increased demand of water in the Delta and climate change, pose a threat to the quality of habitat to support fish and wildlife in Suisun Marsh. It’s clear that increased salinity will have a profound effect on aquatic species, but terrestrial mammals may also be affected by various factors, such as a lack of available water within their respective salinity tolerances and decreased quality forage.

We compared the weights of tule elk harvested on Grizzly Island Wildlife Area in the Suisun Marsh between dry and wet years. We looked at the weights 43 tule elk calves, and 63 female subadults collected over a period of nine years. Average weights for calves were generally lower during periods of drought than during wet years. Female subadult weights were less affected. Increased monitoring of reproduction and mortality on tule elk during periods of drought would allow us to better predict how increasing salinity will affect terrestrial species in Suisun Marsh in the future.