Feeding Highlights

A waterfowl managers only job is to see if the waterfowl are feeding well. Interesting! When I was thinking of coming up with a field project, I was trying to decipher why the information I would be gathering about diving physiology would be significant. Well, this is why. A huge majority of the waterfowl managers job is to ensure that the waterfowl are feeding well. That is their job, and therefore they need scientific backing in order to be certain their waterfowl are feeding well!

Adaptive radiation is something that I am having problems with. From my point of view, I see it as certain animals living in a given environment. In this environment, there are certain things that are preferred over one another. Since there is a lot of competition, however, the animals must find secondary resources to forage on. Therefore, in a given environment animals that would normally compete and maybe run the other into extinction, instead they eat food they wouldn't want as a first choice, but it will permit them to survive. Throughout time of choosing this secondary resource, this animal becomes more specialized to eat the secondary resource and by chance it can become a primary resource through many evolutionary years. There was an interesting example from "What is evolution? Darwin's brilliant idea." One of the exercises was to forage as much "wigglies" as possible from a "tree top" in a given time, however, some of the students had  a mutation. A girl had the mutation of kneeling and foraged more than most. Although, this seemed like it would be a disadvantage, since the other people were grabbing the food from the "tree top" many of the "wigglies" fell and she was able to gather the "wigglies." The mutation was favored for which means natural selection, which is dependent on the environment (i.e. foraging sufficient "wigglies" from tree tops) will favor those mutations in which was capable of adapting to the environment.

How have these animals adapted to foraging? How did favorable mutations that we see in current waterfowl begin? What restrains were imposed on the waterfowl to create a new adaption?

Exploitation of habitats:

Different ways of exploiting habitats:

Swans typically feed by grazing on submerged vegetation, putting their tail end in the air and extending their necks as far down as possible

Geese usually feed in the day. Some of the grazing species must eat for the majority of sunlight hours.  Some geese are even known to "farm" their foods by feeding on one plot and then moving to the another one to allow the plots to grow by just lightly grazing on the plants.

Dabbling ducks are easily spotted in Arcata Marsh, all you have to do is look for a rump sticking up in the air, and you have found a dabbling duck. Many of these ducks will often eat diurnally as well as nocturnally. Some even primarily feed at night, much different than the geese we saw previously. Due to the foraging technique, these dabbling ducks can usually only feed in shallow waters and marshy wetlands by filtering through the water. They use certain techniques to filter through the waters to find the highest densities of seeds an invertebrates since they cannot actually see these in the waters. 

Diving ducks are also easily seen at the Arcata Marsh. If you are looking at a waterfowl species and it magically disappears under the water for a few seconds, you have found a diving duck! Diving ducks are usually always nocturnal. For example, I am studying the Ruddy Duck and I have read many papers saying that it is hard to study the foraging behavior of Ruddy Ducks due to the fact that they feed during the night. In my study, I mainly see the ducks sleeping rather than eating, because they sleep in the day and forage during the night.  

Food selection:

These two graphs show the types of selection that North American Ducks do including plant and animal material! This can show us the difference in mainly vegetarian or mainly animal consumers.
An experiment done to see the different types of food selections within an already preferred food group (mussels) was done with the Tufted Duck. It found that when given the choice, Tufted Ducks often times ate smaller mussels than the larger ones. This is could be because it could be more profitable to collect and eat two small mussels with the same time it would take to collect and eat one large mussel. This most often happened when there was high densities of mussels. When there were lower densities of mussels, they preferred the larger mussels versus the smaller mussels.

Eider ducks being fed. It's amazing to see all of the energy and effort diving ducks must do in order to get the food at the bottom of the water. Female eider is completely endogenous

The Barnacle Geese are very picky when choosing where to forage. They expend a lot of energy in order to forage, so they must ensure that the are getting a sufficient amount of nutrients for the amount of time spent in foraging. And they select the most nutritious part of the plant, the younger and large leaves and peck at very high rates.

Genetics of large geese are basically in all barnacle geese. Bigger geese are the only ones that are reproductively successful, so that is what the genes are in every goose! However, it is the food that the geese receive in their first months of life which determine their size. When seeing a small goose, it is actually just because of the environment they grew up in. Either there was severe weather, unsuitable habitat among other things. Once these geese are of mature age, they will no longer change. 

It was found that the presence of foxes on the breeding grounds prevented feeding. When the fox were present, the geese tended to stay in closer packs to avoid predation. When the foxes were removed, the geese then spread out into land they did not explore previously due to the risk of predation.
Males chase away others while females are foraging, in a way protecting their little patch of vegetation.