Using survival models to estimate invertebrate prey identification times in a generalist stream fish

Estimates of predator feeding rates are important for understanding trophic dynamics. One common method for quantifying feeding rates in fishes combine mass-based diet data with gastric evacuation times to estimate prey mass consumed per predator. An alternative approach is to estimate rates of prey individuals consumed using prey identification times − the time period over which prey remain identifiable in a predator’s stomach. One challenge with the analysis of prey identification times, however, is that the response variable is likely to be censored because the ‘true’ prey identification time cannot be observed directly. Here, we applied survival analysis that can incorporate censored data to estimate the effects of predator body size, water temperature, and prey characteristics (type, count and body size) on identification times in reticulate sculpin (Cottus perplexus). We focused on seven types of prey that are common in this generalist predator’s diet: mayflies (Ephemeroptera), ca...