Predator Feeding Observations

Systematic field surveys a focal predator population in a specified area of the shore.

Year, Date - 2004, 2005, 2006, 2007

Site - there are a total of 6 sites (2 on the NW coast, 2 on the SW coast, 2 on the NE coast. The distance within each pair of sites ranges from ~200m to 24km.)

DayNight - subjectively assessed

TideZone - the location on the shore where the observation was made, subjectively categorized into High, Mid, and Low tide-zones. [In 2004 (the first year) I did not distinguish tide zones, thus "General_unspecified”.]

Predator - Name of the focal species being surveyed. Mainly Haustrum haustorium or Haustrum scobina. Occasional observations of much rarer whelks (e.g., Paratrophon patens) are also included.

PredSize - The shell length of the predator individual in mm.

EstimatedPredSize - True/False - Whether or not the predator size was estimated or measured directly. (The sizes of individuals found in breeding aggregations were estimated so as not to disturb reproduction, for example.)

PossibleChaemoPred - True/False - Determining whether or not a predator individual was feeding was sometimes difficult for one particularly small and abundant species of barnacle (Chamaesipho columna). True denotes an observation where feeding could not be definitively ascertained but seemed possible.

Prey - Either "Not feeding" or the name of the species on which an individual predator was observed feeding.

PreySize - The shell length of the prey being eaten in mm.

EstimatedPreySize - True/False - Whether or not prey size was estimated (because it was crushed, dropped, etc.)

Drilling - True/False - Whether or not the predator had drilled through the shell of the prey.