Determining which birds carry schistosomes responsible for swimmer's itch involves a meticulous scientific process. Here's a glimpse into the methods used to identify and understand the avian hosts:

1. Miracidia Hatching from Feces: Birds are checked for avian schistosomes by hatching miracidia from parasite eggs found in their feces. If hatch-year birds that can't fly test positive, it indicates their exposure to the parasite on a specific lake.

2. Isolating Bird Species and Infection Levels: The species of birds carrying the dermatitis-producing parasite can be isolated, and infection levels can be determined by weighing fecal content and counting miracidia hatching from one gram of feces.

3. Laboratory Snail Exposure: Miracidia from feces can be exposed to lab-reared snails to observe infection. If the cycle can be replicated in the lab, cercariae from lab cultures can be compared with those from naturally-infected snails in areas where swimmer's itch was prevalent.

4. Unique Characteristics of Avian Schistosomes: The behavior, size, and morphology of each avian schistosome species are distinctive, aiding in their identification.

By employing these sophisticated techniques, researchers gain insights into the specific bird hosts and infection levels, contributing to a comprehensive understanding of swimmer's itch dynamics.