Christopher Newport University bottlenose dolphin sightings in Virginia estuaries 2000-2006

Original provider: Andrew DiMatteo, US Navy Dataset credits: Kevin Foss, Christopher Newport University; U.S. Department of the Navy Abstract: The Elizabeth River is bounded almost totally by industrial, urban, suburban, commercial shipping and military facilities. Tidal in nature, the river has low flow, resulting in heavy contamination loads. The population studied is the Northern Migratory Stock of the US Atlantic coast, appearing in this area from May through November. Standard small boat, focal group follow, passive observation techniques were used, along with photography of individuals. Data on location, group size estimates, activities observed and relevant environmental observations were recorded every five minutes. The dolphins appear as individuals or pairs in April and May, with group size increasing in June to a peak mean of 29 animals sighted per encounter. Group size then decreases in October and November. Probability of encountering dolphins ranges from 0% during the winter and early spring to over 80% in July, tapering off towards fall. Activity patterns show greatest diversity in July and August, with travel constituting the main activity early and late. Despite a peak of births in the area in May-June, there is little mating until July, with the incidence of sexual activity peaking in September. Purpose: To better understand the seasonality and behavior of bottlenose dolphins in the lower Chesapeake Bay. Data were originally collected by Mr. Kevin Foss at Christopher Newport University during field seasons from 2000-2006. Data were subsequently acquired by the U.S. Navy in 2013. Supplemental information: [2015-03-24] A few records had a wrong animal count of zero. The value is replaced with a blank representing species presence only. These data are the result of small boat transects with focal group follows, so that sightings were recorded at regular intervals. Therefore, there may be sightings of the same individuals at different times. Records that originally estimated a range for the number of adults were attributed with the median number to be conservative. Three records on land were excluded.