Studying gray whale foraging behavior and body condition over time

Investigators: Dr. Leigh Torres, Clara Bird, Dr. KC Bierlich, Todd Chandler

Studying behavior helps us better understand the relationships between an animal and its habitat. By knowing what an animal is doing, we can then work to understand why and monitor impacts from human activities. We can also link behavior with energetics and study not just the benefits of a behavior, but the energetic costs as well. One way we can do this is by studying the relationship between behavior and body condition. The relationship is particularly important to understand for conservation because it contextualizes the behaviors being observed and is critical for assessing the health of a population.

The GEMM Lab has been studying the Pacific Coast Feeding Group (PCFG) gray whales that forage in the coastal habitat off Oregon since 2015. Each year between May and October, the field team has been collecting a variety of data including photo ID images to identify individual whales, drone footage to measure body condition and record behavior, fecal samples to asses hormonal variability, and GoPro camera drops to describe benthic habitat type and prey availability. This data has also been collected as part of the GRANITE project.

Our objectives are to (1) assess what is considered healthy body condition, (2) describe inter- and intra- seasonal behavior and body condition patters patterns, (3) examine how these patterns differ between individuals and across demographic units, (4) investigate how specific foraging behavior tactics vary by habitat type, (5) study social behavior patterns, (6) measure the energetic costs of different behavior tactics, (7) link foraging behavior to body condition and morphology, and (8) compare the morphology of current PCFG gray whales to ones from over a century ago that were collected via scientific whaling.

By understanding behavior variability and its links to body condition we can work towards assessing how behavioral change caused by disturbance events or environmental change could then affect body condition and overall health.

For more information about this project, please follow along through our blog.

 

Publications:

Pirotta, E.,  Bierlich, K.C.,  New, L.,  Hildebrand, L.,  Bird, C.N.,  Fernandez Ajó, A., &  Torres, L.G. (2024). Modeling individual growth reveals decreasing gray whale body length and correlations with ocean climate indices at multiple scales. Global Change Biology,  30, e17366. https://doi.org/10.1111/gcb.17366

Bierlich, K.C., Kane, A., Hildebrand, L., Bird, C.N., Fernandez Ajo, A., Stewart, J.D., Hewitt, J., Hildebrand, I., Sumich, J., & Torres, L.G. (2023). Downsized: Gray whales using an alternative foraging ground have smaller morphology. Biology Letters, 19(8), 20230043. https://doi.org/10.1098/rsbl.2023.0043

Torres, L.G., Bird, C.N., Rodriguez-Gonzalez, F., Christiansen, F., Bejder, L., Lemos, L., Urban, J.R., Swartz, S., Willoughby, A., Hewitt, J., and Bierlich, K.C. (2022). Range-Wide Comparison of Gray Whale Body Condition Reveals Contrasting Sub-Population Health Characteristics and Vulnerability to Environmental Change. Frontiers in Marine Science, 9. https://www.frontiersin.org/article/10.3389/fmars.2022.867258  

Soledade Lemos, L, Burnett, J.D., Chandler, T.E., Sumich, J.L., Torres, L.G. (2020). Intra- and Inter-Annual Variation in Gray Whale Body Condition on a Foraging Ground. Ecosphere 11(4 ): e03094. https://dx.doi.org/10.1002/ecs2.3094.

Burnett, J.D., Lemos, L., Barlow, D., Wing, M.G., Chandler, T., Torres, L.G. (2019). Estimating Morphometric Attributes of Baleen Whales with Photogrammetry from Small UASs: A Case Study with Blue and Gray Whales. Marine Mammal Science, 35(1): 108-39. https://dx.doi.org/10.1111/mms.12527.

Torres, L.G., Nieukirk, S.L., Lemos, L.S., Chandler, T.E. ( 2018). Drone Up! Quantifying Whale Behavior from a New Perspective Improves Observational Capacity. Frontiers in Marine Science, 5(319) . https://dx.doi.org/10.3389/fmars.2018.00319.

Supplemental material: Full compilation video of gray whale behaviors

 

Videos:

 

Collaborators:

Cascadia Research Collective

 

Funding and Support:

Office of Naval Research Marine Mammal Program

Oregon Sea Grant

NOAA/NMFS Ocean Acoustics Program   

OSU Marine Mammal Institute

We are able to collect detailed behavior and body condition data using Unoccupied Aerial Systems (UAS, ‘drones’). These data will help us study how behavior varies across space, time, and individual body condition and sex.