PROJECTS

This project seeks to utilize the newly developed statistical methods from the Atlantic behavioral response study (BRS) and apply them to satellite-tagged pilot whales from both the Atlantic and Pacific. In the Atlantic BRS, the research team has used a class of movement models known as continuous time, discrete space (ctds) models (Hooten and Wikle, 2010; Hooten et al., 2010; Hanks et al., 2015).  These models are used to examine two factors of movements: 1) the speed with which animals move through or reside in a given space, and 2) the choices animals make when moving.  To parameterize the movement response to sonar, the BRS team constructed rasters that represented the distance to the sound-source, and then estimated attractive/repulsive movements in relation to that source. By pairing the model output with estimated received level at the time of exposure, the Atlantic BRS team could then quantify how likely an animal is to move away from a source as a function of received level (Southall et al., In review). We will extend this approach using the ctds model from Johnson et al. (2021) to examine movement response to dynamic covariates. Specifically, we intend to build a dynamic raster cube that represents the ambient wind-driven noise and the sound propagation model for each exposure.

Tasks for this project include:

1) Model received levels of active sonobuoys and helicopter-dipping sonar for PMRF pilot whales, and finish   received level models for hull-mounted MFAS. 

2) Model pilot whale received levels for simulated and operational ship MFAS in Atlantic using methodology  developed for goose-beaked whales.

3) Conduct social network analysis on PMRF pilot whales to examine exposure histories and assess response at the group level.

4) Apply ctds models to all track data from both populations to assess horizontal movement.

5) Apply standard Hidden Markov models to the dive summary data to examine if a received level covariate impacts either state transition probabilities, or state-dependent distributions.

6) Using the results of the ctds models, assess behavioral response at the level of the individual and, when possible, the group (e.g., multiple animals in a group tagged together, or responsiveness in a social network framework; look at responsiveness across MFAS sources (simulated, sonobuoy, helo-dipping, operational hull-mounted).