What dual threat is posed to the SFGS ecosystem by the presence of non-native American bullfrogs?
Answer
Preying on juveniles and competing for amphibian prey
Invasive species represent a significant compounding threat to the already fragile San Francisco garter snake populations, particularly the non-native American bullfrogs. These invasive amphibians exert pressure in two distinct ways that undermine the snake's reproductive success and food supply. First, bullfrogs act as direct predators, consuming juvenile San Francisco garter snakes, thus reducing recruitment into the adult population. Second, they compete aggressively with the snakes for shared food resources. Since the snakes heavily rely on amphibians, especially the California Red-Legged Frog, the bullfrogs’ presence directly depletes the snakes' primary food base.
Related Questions
When was the San Francisco garter snake officially listed as endangered by the U.S. Fish and Wildlife Service (FWS)?How many known significant populations of SFGS currently remain across its fragmented habitat?What specific type of underground refugia do San Francisco garter snakes utilize for winter hibernation and summer dormancy?Which threatened amphibian, heavily dependent on shallow water for metamorphosis, forms a critical part of the SFGS diet?What minimum adult census target, maintained across 10 populations, does the 1985 Recovery Plan aim for before considering the SFGS recovered?According to demographic simulations, what is the recommended duration for releasing head-started juveniles into a single subpopulation to maximize viability?What dual threat is posed to the SFGS ecosystem by the presence of non-native American bullfrogs?What specific visual characteristics make the San Francisco garter snake prone to illegal poaching for the pet trade?What is the ideal shallow water depth, measured in centimeters, required near pond edges for SFGS foraging between May and July?Which two specific open space preserves are mentioned as actively supporting SFGS populations while also being managed as cattle ranches?