Part of our study will be to map habitat use by dolphins. By keeping track of the latitude and longitude of each sighting, we will be able to relate dolphin distribution and behavior to water depth and sea-grass beds. Latitude and longitude of sightings of individual animals we recognize will allow us to plot their home ranges on a map.
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9:36
Tt traveling south, surfaced two times in channel.
28° 37.77' N
80° 48.21' W
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10:05
Single Tt heading northeast about 100 m from channel.
28° 42.08' N
80° 47.63' W
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The "channel" refers to the dredged navigation channel. The main north-south channel in the Indian River Lagoon is the Intracoastal waterway, which runs from Key West to Maine.
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10:10 Four or five animals. Probable feeding.Same location: three different Tts moving in different directions. Undetermined behavior. No fish seen, but possibly feeding. We moved toward Spoil Island.
Two Tts spotted off Spoil Island, probably same from first group of four to five.
28° 42.12' N
80° 47.49' W
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We try to place dolphin behavior in several broad categories: traveling, feeding (when we see a fish in the dolphin's mouth), probable feeding (when the dolphin appears to be chasing fish but we don't actually see any fish), milling (when dolphins move slowly in different directions without moving in any one direction). We also note socializing, which covers a wide range of behavior, including mating and playing.
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10:21
Four feeding, traveling in unison. Large boat goes by in channel.
Tts still in area until 10:23 but not seen.
28° 42.08' N
80° 47.77' W
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Watching dolphins is so exciting that we have to remember to keep our minds on our study (and to watch where the boat is going)! As our study develops we will make different kinds of observations on different days. For example, some days our primary objective will be to take photos. On other days we'll look at behavior and try to follow dolphin groups for a long time. On still other days we may watch dolphin behavior around boats or make recordings of dolphin sounds. |
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10:27 Still following same group of four from Spoil Island. One has definite slash mark a third of a foot from dorsal-fin base. Got photo. Other one possibly had freeze brand. Never got good ID or photo.
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See photo..
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10:33 Four animals still traveling southwest toward channel.
28° 41.74' N
80° 47.91' W
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See photo.
See photo.
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10:43
Two Tts traveling north across channel. We stopped and saw three to four behind our boat, toward the island. One with distinct dorsal markings but could not get photos near island.
28° 43.52' N
80° 46.07' W
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10:50
Still seeing one of the pair near island, which surfaced two times.
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11:00
Reached the mouth of the Haulover Canal, on the Indian River side. Boat bogging down in sea grass.
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11:27
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We spotted the presence of the manatee from its "footprint." The footprint is a boil (churn) in the water that the manatee makes with its tail as it swims. Sometimes we actually see the manatee's nose sticking out of the water. |
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11:44
Two Tts (one young) in channel at the mouth of Haulover Canal on the Mosquito Lagoon side. Feeding. Fish jumped. Two pelicans also in area.
28° 44.66' N (channel marker 46)
80° 44.83' W
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The larger of the two animals was probably a female. This particular young animal was not a calf but probably a juvenile. It is likely that this was a female and her offspring, but we are not as sure as we would be if it had been a small calf.We often use bird-feeding activities to locate dolphins. It appears that the dolphins chase the fish up to the surface where the pelicans can get them easily. |
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11:52
Still in area. Several pictures taken. One had definite nicks on dorsal fin, other one looked fairly unmarked.
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See photo.
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12:00
Went north into Mosquito Lagoon. Saw no dolphins between channel marker 46–20 or on the way back
south.
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The channel marker system in the IRL are buoys painted with numbers. These help boaters identify their locations. The markers help us to plot the locations of dolphins. |
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12:53
Back at Haulover Canal. Three Tts in channel at the mouth of the canal. One looked to be spyhopping, with its rostrum above water for a few seconds. Also seen rolling. Possible socializing. |
"Spyhopping" is a dolphin or whale sticking its head straight up out of the water. We are not sure what this dolphin was doing. It was probably some form of social behavior."Rolling" is an animal rolling over in the water just like a dog rolls over on the grass. We don't know why this dolphin was rolling. It may have been feeding or socializing. |
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13:05
Spotted small manatee about 500 m east of bridge in Haulover Canal.
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13:13 Spotted another manatee, 50–75 m west of bridge in center of channel. It lifted head high, then rolled and went under.
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13:23
Back in Indian River. Water is still fairly calm.
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13:54
Two Tts. Undetermined behavior. No freeze brands.
28° 43.10' N
80° 46.62' W
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14:13
Two Tts in channel in deeper water. Surfaced a few times then gone. Undetermined behavior.
28° 39.94' N
80° 43.68' W
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See photo.
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14:22
Single Tt traveling. Stayed parallel with boat for several minutes. Seen again near channel
marker 20. No photos taken.
28° 39.88' N
80° 48.61' W
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Actually, the boat was traveling parallel to the dolphins! However, dolphins appear to like to ride in the bow waves (wave made by the front of the boat) or in the wake (waves made by the back of the boat). Our boat isn't big enough to make waves that dolphins would like.
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14:55
Returned back at Parrish Park ramp. Ended observations.
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While our study has just started, we've already collected photos of several animals with unique marks on their dorsal fins. I'm sure we'll see them many times in the coming weeks. We've also started to gather information on dolphin habitat use patterns. For examples, dolphins seem to like to hang out at the east end of Haulover Canal.
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