Factors influencing the acquisition of an attraction response to human provisioning by bottlenose dolphins in Cockburn Sound

Brief description

The contribution of four factors to the acquisition of attraction responses to human provisioning by dolphins in Cockburn Sound: 1) individual patterns in the use of high boat density areas; 2) age-class; 3) sex; and 4) close associations with 'experienced' individuals (i.e. individuals that had previously become conditioned to human provisioning) were considered using unpublished data from Rebecca Donaldson (1993-1997) and original data collected for the thesis (2000-2003) from Cockburn Sound. The overall objectives were: (a) to identify and characterise predictor variables for the acquisition of an attraction response; (b) to examine interactions between these variables; and (c) to address the potential influence of social learning.

Lineage

Maintenance and Update Frequency: notPlanned

Statement: - Identification of an attraction response in dolphins - Between 1993-2003 a sub-set of individuals within the residential dolphins exhibited a series of behavioural events indicating that they were conditioned to human interaction by food reinforcement (sensu Samuels and Bejder 2004). Chapter 5 described these behavioural events and the basis for classifying dolphins as conditioned to human interaction by food provisioning. Attraction responses are characterised by: (a) the strengthening of an animal's behavioural response to a stimulus over time because of positive reinforcement and; (b) the movement of animals towards the stimulus (Whittaker and Knight 1998). Dolphins were categorised as having acquired an attraction response based upon two criteria: 1) utilisation of the behavioural events indicating that they were conditioned to human interaction by food reinforcement and 2) a sequential series of observations indicating a positive change in the occurrence of these behavioural events. Individual were determined to have fulfilled the second requirement if a longitudinal series of behavioural surveys was available that included: (a) an initial series of surveys in which the individual did not exhibit the behavioural events indicative of conditioning and; (b) a subsequent series of surveys in which the individual was observed to exhibit these behaviours. One individual was considered conditioned at the start of studies in 1993 and thus an initial series of surveys was unavailable. The term "acquisition" refers to the act of first developing a response; the date on which an individual was first observed to exhibit an attraction response was used as the time at which the animal acquired the response. In a few cases, it was possible to observe behaviours that suggested initial stages of the acquisition of an attraction response (e.g. a nonprovisioned individual remaining within 10m of and orientated towards a boat while another dolphin was provisioned). However, generally individuals were observed not to exhibit the behavioural events for a series of years and then to exhibit the events during interactions with humans.

Statement: - Spatial variation in the density of recreational boats within Cockburn Sound - Recreational boats were the principal provisioning source observed for dolphins in Cockburn Sound (Chapter 5 of thesis). During the systematic sampling of belt transects in 2000-1 (see Chapter 3 of thesis), data were collected on the number of occupied boats anchored or drifting within 200m to either side of the transect line. Boats that were making way at planing speed were not recorded as present within the Habitat type because they may have been transiting through the Habitat type. Boat densities were calculated by multiplying the transect length by the width of the "boat" transect (400m) to give the area sampled (in km2) and dividing the number of boats observed by the area sampled. Transect samples conducted in conditions of sea state Beaufort 3 (occasional white-caps) were included in the analyses because of the high sightability of boats. These data were used to calculate a mean boat density for each Habitat type (as defined in Chapter 3 of thesis).

Notes

Credit
Donaldson, Rebecca

Purpose
To manage the harmful human-wildlife interactions that are based on attraction responses to anthropogenic resources.