Migrating Eastern North Pacific Gray Whale Behavior Compared Over Multiple Timescales
Mysticetes (baleen whales) often make long, annual migrations from high latitude summer feeding areas to low latitude wintering areas. Eastern North Pacific gray whales (Eschrichtius robustus) migrate within a few kilometers from shore for most of their route from summer feeding areas in the Bering,...
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ftcdlib:oai:escholarship.org/ark:/13030/qt5zw7j3w4 2023-05-15T15:37:17+02:00 Migrating Eastern North Pacific Gray Whale Behavior Compared Over Multiple Timescales Guazzo, Regina Anne Hildebrand, John A 2018-01-01 application/pdf https://escholarship.org/uc/item/5zw7j3w4 en eng eScholarship, University of California qt5zw7j3w4 https://escholarship.org/uc/item/5zw7j3w4 public Acoustics Ecology Conservation biology Behavior Bioacoustics Gray Whales Infrared Camera Migration Passive Acoustic Monitoring etd 2018 ftcdlib 2019-09-13T22:52:50Z Mysticetes (baleen whales) often make long, annual migrations from high latitude summer feeding areas to low latitude wintering areas. Eastern North Pacific gray whales (Eschrichtius robustus) migrate within a few kilometers from shore for most of their route from summer feeding areas in the Bering, Chukchi, and Beaufort Seas to wintering areas in the lagoons along the south-western coast of the Baja California Peninsula in Mexico. This dissertation combines passive acoustic recordings, infrared camera video, and visual sightings to investigate gray whale behavior and how it changes across different timescales. I use a four-element hydrophone array in central California to present the first published full-season acoustic monitoring and tracking of migrating gray whales. I describe the characteristics of calls produced by migrating gray whales and analyze how these characteristics change due to propagation. I show that gray whale behavior changes on diel and seasonal timescales. Notably, gray whales increase their vocalizations at night but their mean swimming behavior does not change, contrary to previous assumptions used in population size estimates. Over seasonal timescales, vocalizing gray whale swimming behavior aligns with previous observations. I explore how passive acoustic and infrared camera monitoring can help quantify whales by calculating cue rates or call and blow rates for migrating gray whales. Acoustic calling rates indicate that the gray whale population size is greater than estimated using visual sightings alone and that calling rate increases over the southbound migration. Infrared camera blow rates are less affected by whale behavior and are useful for daytime and nighttime monitoring, but are limited by visibility and distance. To understand gray whale behavior over seven migration seasons, I use visual daily counts at two sites and single-hydrophone call detections which indicate that migratory behavior seems to be driven more by intrinsic than the tested environmental factors. I find that the proportion of the population using a coastal route through the Southern California Bight, especially past Los Angeles, increased over these years. Understanding the behavior of migrating gray whales will help improve abundance estimates and determine how these whales may be impacted by nearshore anthropogenic activities and climate change. Other/Unknown Material baleen whales Chukchi University of California: eScholarship Baja Pacific |
institution |
Open Polar |
collection |
University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
English |
topic |
Acoustics Ecology Conservation biology Behavior Bioacoustics Gray Whales Infrared Camera Migration Passive Acoustic Monitoring |
spellingShingle |
Acoustics Ecology Conservation biology Behavior Bioacoustics Gray Whales Infrared Camera Migration Passive Acoustic Monitoring Guazzo, Regina Anne Migrating Eastern North Pacific Gray Whale Behavior Compared Over Multiple Timescales |
topic_facet |
Acoustics Ecology Conservation biology Behavior Bioacoustics Gray Whales Infrared Camera Migration Passive Acoustic Monitoring |
description |
Mysticetes (baleen whales) often make long, annual migrations from high latitude summer feeding areas to low latitude wintering areas. Eastern North Pacific gray whales (Eschrichtius robustus) migrate within a few kilometers from shore for most of their route from summer feeding areas in the Bering, Chukchi, and Beaufort Seas to wintering areas in the lagoons along the south-western coast of the Baja California Peninsula in Mexico. This dissertation combines passive acoustic recordings, infrared camera video, and visual sightings to investigate gray whale behavior and how it changes across different timescales. I use a four-element hydrophone array in central California to present the first published full-season acoustic monitoring and tracking of migrating gray whales. I describe the characteristics of calls produced by migrating gray whales and analyze how these characteristics change due to propagation. I show that gray whale behavior changes on diel and seasonal timescales. Notably, gray whales increase their vocalizations at night but their mean swimming behavior does not change, contrary to previous assumptions used in population size estimates. Over seasonal timescales, vocalizing gray whale swimming behavior aligns with previous observations. I explore how passive acoustic and infrared camera monitoring can help quantify whales by calculating cue rates or call and blow rates for migrating gray whales. Acoustic calling rates indicate that the gray whale population size is greater than estimated using visual sightings alone and that calling rate increases over the southbound migration. Infrared camera blow rates are less affected by whale behavior and are useful for daytime and nighttime monitoring, but are limited by visibility and distance. To understand gray whale behavior over seven migration seasons, I use visual daily counts at two sites and single-hydrophone call detections which indicate that migratory behavior seems to be driven more by intrinsic than the tested environmental factors. I find that the proportion of the population using a coastal route through the Southern California Bight, especially past Los Angeles, increased over these years. Understanding the behavior of migrating gray whales will help improve abundance estimates and determine how these whales may be impacted by nearshore anthropogenic activities and climate change. |
author2 |
Hildebrand, John A |
format |
Other/Unknown Material |
author |
Guazzo, Regina Anne |
author_facet |
Guazzo, Regina Anne |
author_sort |
Guazzo, Regina Anne |
title |
Migrating Eastern North Pacific Gray Whale Behavior Compared Over Multiple Timescales |
title_short |
Migrating Eastern North Pacific Gray Whale Behavior Compared Over Multiple Timescales |
title_full |
Migrating Eastern North Pacific Gray Whale Behavior Compared Over Multiple Timescales |
title_fullStr |
Migrating Eastern North Pacific Gray Whale Behavior Compared Over Multiple Timescales |
title_full_unstemmed |
Migrating Eastern North Pacific Gray Whale Behavior Compared Over Multiple Timescales |
title_sort |
migrating eastern north pacific gray whale behavior compared over multiple timescales |
publisher |
eScholarship, University of California |
publishDate |
2018 |
url |
https://escholarship.org/uc/item/5zw7j3w4 |
geographic |
Baja Pacific |
geographic_facet |
Baja Pacific |
genre |
baleen whales Chukchi |
genre_facet |
baleen whales Chukchi |
op_relation |
qt5zw7j3w4 https://escholarship.org/uc/item/5zw7j3w4 |
op_rights |
public |
_version_ |
1766367745847328768 |