Dolphins!

Today was our first day on the water! We found 3 groups of dolphins in different parts of our study area. The region we are focusing on for this month includes the near shore waters close to the island of Key West.

We lost the first group within minutes of sighting them. Dolphins are actually fairly easy to lose sight of, especially when the group size is small and our first group included only two animals. Bottlenose dolphins can stay under the water between surfacing to breath for a pretty long time (up to 10 min) and they surface maybe twice per minute on average. So if you happen to be looking for them in the wrong place, you can miss seeing them surface and before you know it, they have moved beyond your sight.

Group two was far easier to keep track of, with 6 adults and 1 calf. This group moved right past a snorkeler diving for lobster.

One of the adults in this group had been in some recent scuffles. You can see the evidence of bites on the side of this animal. While we followed this group, fighting between some of them was occurring. Bottlenose dolphins fight by either ramming one another, hitting one another with the fluke (tail) or by biting. Evidence of recent fighting can be noted by the presence of tooth rakes, which are parallel lines on the skin that appear white since the top layer of skin has been removed by the teeth.  This is also how dolphins get notches on the trailing edge of the dorsal fin (bites). 

Group three had 5 adults traveling over very shallow sea grass bed. For this group we collected behavior data, including leadership. When we collect leadership data, we monitor the position of group members, who initiates direction change and whether they are successful. In group three, only one animal contributed to group leadership while the group traveled. This is usual for what we see in groups off Key West. Between 1 and 3 dolphins will contribute to >20% of the leadership when traveling. Usually only one or two animals lead (~90% of all groups, no matter what the group size), and never more than three.