Update from Daniela: (charts with data analysis to come- Anna)

Dear Teams,

The season is really over. The house has been locked, the staff is returning home from the field and there is lots and lots of work to do to analyze the data, summarize the information and, yes…prepare for next year. Our field season is starting again next August and will again run until the end of October. There will be some slight changes based on your observations, your comments and the evolution of the work as we get answers to some questions and move on to others. One big change is going to be the accommodations. Although Pacific Grove served us well as a base and I love the town, we would like to be closer to the field and to the animals so we decided to move to Pajaro Dunes Colony. You have seen it…from the boat: that funky line of houses right on the beach. Well, that will be our new base. The house is very nice and close to the beach…maybe not as big as the Pacific Grove one but certainly close to Moss Landing and the wildlife.

Peter has been driving back to Massachusetts with the car and the data. He will be home today. I was in Mexico where I attended a marine mammal conference and then in Florida where I attended another that was especially interesting because of the sea otter workshop which gave me a lot to think about. It was the perfect motivator to get me to look at some of our data from this summer. I looked at the 5-minute sampling intervals that you and the staff collected from the parking lot in Moss Landing throughout the day looking at the sea otter raft and the other otters around it. The story is not surprising but interesting. Most of the sea otters observed in Elkhorn Slough are juvenile males, which confirms that the slough is still a male area and one where juvenile males spend their maturing years waiting to move out and possibly become territorial males by competing with the current “kings of the harems”. Some of them will become harem holders and others will perish trying or will be confined to peripheral areas perhaps managing to sneak into a territory every once in a while and mate with a female while the boss is busy. The interesting question is: How many of these juveniles will actually become territorial males and how many will make it? There is no answer for now and pursuing the question will take some collaborative efforts with other researchers and more funding, but we are exploring this possibility.

In the meantime, back in the slough these animals spend most of their time resting in Area 2, in the large raft you have observed, and foraging (but not in Area 2). We are looking at the data for indications of where most of the foraging occurred. We know that the slough main channel on both sides of the highway bridge is an important foraging area; however, the open ocean just in front of Moss Landing seemed to be as important this year. Figure 1 gives you the frequency of occurrence of the behaviors you have observed in Area 2 through the summer (this is part of the data you have helped collect!). Sea otters rested 47% of their time, groomed 23%, interacted with one another 11%, moved in and out or within Area 2 9% of the time and only foraged 1% of the time in this area. Most of the foraging occurred outside of Area 2.

The largest numbers of otters in Area 2 were found early in the morning between 6 and 7 am, and the numbers varied widely throughout the day. However, the number of otters tended to decrease later in the morning, increase again around noon and decrease in the afternoon as animals went out to forage and use other areas of the slough or offshore. Knowing when otters rest is important. Disturbance of resting patterns by boats and people may affect their ability to recuperate in between energetically demanding foraging trips. When sea otters rest, they become dry and warm which saves them a lot of energy. When they are disturbed, they dive or roll and become wet, therefore consuming more calories to stay warm. Continuous disturbance may therefore have effects on their health as they need to forage longer hours to recuperate calories lost. By identifying times of day and locations of resting areas we can suggest to the public appropriate behaviors to ensure diminished disturbance. Our initial data are giving us a good clue. We are going to continue to test the hypotheses I just mention to figure out the costs of disturbance to sea otters. Thanks for your help in getting these results.

There is still much more data to analyze and I will keep you posted. I wish you all a Happy Thanksgiving (for Americans!) and a great Holiday season.

All the best

Daniela