According to Birds of North America there are four foraging methods used by Red-breasted Mergansers which are Cooperative Herding, Individual Search, Shallow Diving and Deep Diving. Even though there is a pair of birds in the image above they are using the Individual Search method which involves swimming continuously with the head submerged while searching for prey. These two birds were in a shallow lagoon at the north beach of Fort De Soto County Park.
This Red-breasted Merganser was photographed as it foraged in the Gulf of Mexico also using the Individual Search method but seemed to be caught unawares when a rather large wave came up to the bird. Not the best image as far as getting eye contact from my subject but I can see the eye and I am fairly certain the bird could see me too.
In my observations of Red-breasted Mergansers foraging I noticed that they foraged for long periods of time and their activity level was high and that they would often take a small break while foraging to briefly look around. Perhaps that was to make sure there were no predators in the area.
After a lengthy period of foraging I also noticed that Red-breasted Mergansers would climb out of the water to rest. I photographed this resting Red-breasted Merganser on the shoreline of the Gulf of Mexico at Fort De Soto’s north beach. I was able to belly crawl up to the merganser without disturbing it.
One other foraging behavior I saw and do not see mentioned at BNA is that Red-breasted Mergansers would follow Reddish Egrets who were actively foraging and then would capture prey that the egrets scattered towards them. The Reddish Egrets paid the Red-breasted Mergansers very little attention if any at all but the mergansers seemed to benefit from the feeding activity of the egrets. In a way it is a form of Cooperative Herding but the mergansers are using the Reddish Egret to do the herding.
Soon I should be seeing Red-breasted Mergansers here in Utah and I hope that I will see and photograph more of their foraging behaviors.