DUCKLING WOOD DUCKS, OTTERS, AND A WEEK OFF

Sometimes they do their own thing

 at other times we do things together

and every now and then ... it's the same but different?

SAMPLING FOR AVAILABLE FOOD RESOURCES

Even though Western pond turtles forage in the water, the aquatic ecosystem has strong links to the adjacent terrestrial ecosystem. Further, it is common for a terrestrial insect to land in or near the water and when a turtle sees it, they eat it. Therefore, I am sampling both habitats, as you can see from my previous posts that include pictures of terrestrial insects (i.e., beetles and grasshoppers). I use brush net sweeps along the bushes and bankside vegetation to sample the terrestrial ecosystem. In the aquatic ecosystem, I use a D-net to pull samples from the emergent vegetation and the substrate (creek bottom landscape). To do this I jab the net into the sample area and then with a twisting and jabbing motion I stir the area up and then withdraw the sample. My other tool is activity-traps that I fashion from plastic soft and juice drink bottles. I put a small amount of bait, usually sardines, inside of them to attract carnivores and scavengers, which largely encompasses the feeding habits of all the organisms living there. It seems that nobody turns down a free meal!

The direct impact on my research is that I can readily identify organisms or parts of them I find in the stomach contents of Western pond turtles. In addition, it gives me peripheral information such as the variety of available food resources and its seasonality. In the future, I want to examine in grater detail, because it is helpful when measuring the effects of human activity on these ecosystems.

YIKES, THE OTTERS ARE BACK!

The "calling cards" or scats left behind by otters are useful tool for me and let other predators in the area know they are present. 

Otter feces rich in crayfish parts.

Generally, North American river otters (Lontra canadensis) seem to be largely absent from Santa Rosa Creek. Occasionally I see an occasional scat (feces), but rarely encounter them until near the end of July. When they move into the area to feed on crayfish, they are competing with Western pond turtles for the same food resource. The larger, faster mammal out competes the turtles for the most available food resource.

In addition, they also attempt to remove the punctured cans of sardines I put in turtle traps as bait. They dislodge the traps from their moorings, sinking them, making it possible to drown any turtle that is inside. To prevent this kind of incident I set out activity traps to discover if they are present during mid-July along the areas of Santa Rosa Creek I plan to work. These baited traps, filled with sardines, attract the otters and they drag them from place to place while trying to remove the sardines.

On July 20, 2012, I thought I heard otters foraging in the bulrushes, found scats (feces), and crayfish parts along the section of the bank I was planning to work. Because of this, I set out two traps to confirm my suspicions. The next day, I found them buried deep inside the emergent vegetation and bulrushes instead of being along the edge, a clear sign that otters are present. My final confirmation was hearing an otter yipping at me, as if to warn me off, as I approached the area to retrieve the traps.

In addition, they were working along a nearby bike trail I use for access to other sites. Hence, I took a week off, examined and compiled my data, and took some time to rest and gather my thoughts. Therefore, I did not add to the blog last week.