This is B-roll video collected during the fall of 2024 on the Alaskan shores of the Chukchi Sea.
Q&A: New Drone-Based Method Helps Monitor Walrus Health
Innovative drone technology provides critical insights into the body condition and health of Pacific walruses in a changing Arctic.
Return to USGS Alaska Q&A Series
The U.S. Geological Survey has developed a new method to assess the body mass and condition of adult and young walruses with help from partners at zoos and aquariums. Using quiet drones flown high above herds resting on shore, scientists can assess the health of female walruses and their calves. This method also lays the groundwork to develop monitoring programs to track mortality events and calf survival.
In this Q&A, we talk with Karyn Rode and Tony Fischbach, both research biologists with the USGS Alaska Science Center, about this new approach to understanding walrus health.
Q: Can you provide some background information about this new drone-based method for monitoring?
Tony: Since 2007, as many as 190,000 Pacific walruses—primarily females and calves—have migrated each autumn from offshore feeding grounds to the coasts of northwestern Alaska to rest on shore. This shift is due to the loss of their preferred habitat: Arctic sea ice. Historically, females and juveniles would haulout on ice over feeding grounds in the Chukchi Sea, but the loss of sea ice forces them to spend more time swimming and less time feeding. This increased energy expenditure can affect their body condition, making it difficult for females to meet the demands of birthing and feeding calves for the year or more it takes to raise them to independence—an issue of great interest to federal and Alaska Native co-management partners, who are deeply invested in the health, sustainability, and population dynamics of the walrus.
Karyn: Marine mammals, including walruses, are notoriously difficult to study in the wild because observation and health assessments often disturb them. However, the large coastal herds of walruses now offer a rare opportunity to monitor population health. Body mass, a key indicator of whether walruses are balancing energy intake with expenditure, can be assessed without disturbance using drone imagery.

Q: Wow, sounds really cool. But how do the images provide information on body condition? Can a photo tell you how much a walrus weighs?
Karyn: Great question and you are right, it’s a bit more complicated. We first had to determine the relationship between actual body mass, length, and width of a walrus to what can be measured in a drone image. And that is a big part of this paper: developing that relationship with walruses in human care. We are so thankful for our zoo partners because without their collaboration and access to walruses in human care, we would not have been able to develop this approach.
Tony: The study we just completed examined the relationship between aerial imagery and the body mass of walruses at six zoos and aquariums (Indianapolis Zoo, Point Defiance Zoo, SeaWorld San Diego, and SeaWorld Orlando), Belgium (Pairi Daiza), and Germany (Hagenbeck Zoo). Results showed that measurements from aerial images were reliable predictors of body mass, allowing researchers to estimate the body mass of wild walruses using drone survey data. So, using drone imagery to monitor body condition is a breakthrough for walrus research and monitoring. This approach is simple and relies on partnership with Alaska Native communities that depend on walruses. The USGS would be unable to gather this monitoring data without the help of Native hunting families.

Q: Sounds like those partnerships were critical to making this work happen. What’s next?
Karyn: Well, early assessments of drone imagery suggest that over 200 Pacific walruses are appropriately positioned to be measured in a single image, which should allow us to measure about 7,000 animals within the herd over the course of a haulout. During 2024, we collected the first two dozen aerial surveys in partnership with Alaskan Native managers to begin laying the groundwork to monitor walruses over the coming decades. With the pace of ecological change increasing in the Arctic, there is growing demand for tools that can track the health of marine species. We feel that this study contributes to the USGS mission of developing approaches for tracking the health of Department of the Interior-managed resources, particularly reproductive-age female and juvenile Pacific walrus—key segments of the population that are most susceptible to the effects of these changes.




Sounds from a large herd of walruses resting on Alaskan shores of the Chukchi Sea
Deep full barks and calls of individual walruses near the edge of the herd are audible over a continuous rhythmic humming sound that arises from the calls of tens of thousands of walruses from deeper within the herd. Waves can be heard as they crash onto shore and slides up the beach before retreating.
Walrus Research

This is B-roll video collected during the fall of 2024 on the Alaskan shores of the Chukchi Sea.
Sounds from a large herd of walruses resting on Alaskan shores of the Chukchi Sea recorded. Deep full barks and calls of individual walruses near the edge of the herd are audible over a continuous rhythmic humming sound that arises from the calls of tens of thousands of walrsues from deeper within the herd.
Sounds from a large herd of walruses resting on Alaskan shores of the Chukchi Sea recorded. Deep full barks and calls of individual walruses near the edge of the herd are audible over a continuous rhythmic humming sound that arises from the calls of tens of thousands of walrsues from deeper within the herd.
This is B-roll video collected during the fall of 2024 on the Alaskan shores of the Chukchi Sea.
This is B-roll video collected during the fall of 2024 on the Alaskan shores of the Chukchi Sea.
Comparison of the body area of walruses in human care in two positions (head up and flat) used for estimating body mass.
Comparison of the body area of walruses in human care in two positions (head up and flat) used for estimating body mass.

An adult female walrus being positioned by marine mammal trainers at SeaWorld Orlando, Florida for measurement using aerial photographs (see camera at the top of the image). These images were taken as part of a USGS study in collaboration with zoos and aquaria in the United States and western Europe for validating aerial imagery as a method for monitoring the b
An adult female walrus being positioned by marine mammal trainers at SeaWorld Orlando, Florida for measurement using aerial photographs (see camera at the top of the image). These images were taken as part of a USGS study in collaboration with zoos and aquaria in the United States and western Europe for validating aerial imagery as a method for monitoring the b
Aerial view of the edge of a large walrus herd hauled out on the northwestern shores of Alaska. The image was taken using an unoccupied aerial system, commonly referred to as a survey drone that was flown to collect imagery of walruses resting on shore in 2018 and 2019 for estimating the abundance of walruses that use the U.S.
Aerial view of the edge of a large walrus herd hauled out on the northwestern shores of Alaska. The image was taken using an unoccupied aerial system, commonly referred to as a survey drone that was flown to collect imagery of walruses resting on shore in 2018 and 2019 for estimating the abundance of walruses that use the U.S.

Walruses identified as being in an appropriate position for measurement from an image collected by a USGS survey drone on September 6, 2018, at a haulout near Point Lay, Alaska.
Walruses identified as being in an appropriate position for measurement from an image collected by a USGS survey drone on September 6, 2018, at a haulout near Point Lay, Alaska.
Photogrammetry-based body condition for monitoring an Arctic marine mammal experiencing habitat loss
Innovative drone technology provides critical insights into the body condition and health of Pacific walruses in a changing Arctic.
Return to USGS Alaska Q&A Series
The U.S. Geological Survey has developed a new method to assess the body mass and condition of adult and young walruses with help from partners at zoos and aquariums. Using quiet drones flown high above herds resting on shore, scientists can assess the health of female walruses and their calves. This method also lays the groundwork to develop monitoring programs to track mortality events and calf survival.
In this Q&A, we talk with Karyn Rode and Tony Fischbach, both research biologists with the USGS Alaska Science Center, about this new approach to understanding walrus health.
Q: Can you provide some background information about this new drone-based method for monitoring?
Tony: Since 2007, as many as 190,000 Pacific walruses—primarily females and calves—have migrated each autumn from offshore feeding grounds to the coasts of northwestern Alaska to rest on shore. This shift is due to the loss of their preferred habitat: Arctic sea ice. Historically, females and juveniles would haulout on ice over feeding grounds in the Chukchi Sea, but the loss of sea ice forces them to spend more time swimming and less time feeding. This increased energy expenditure can affect their body condition, making it difficult for females to meet the demands of birthing and feeding calves for the year or more it takes to raise them to independence—an issue of great interest to federal and Alaska Native co-management partners, who are deeply invested in the health, sustainability, and population dynamics of the walrus.
Karyn: Marine mammals, including walruses, are notoriously difficult to study in the wild because observation and health assessments often disturb them. However, the large coastal herds of walruses now offer a rare opportunity to monitor population health. Body mass, a key indicator of whether walruses are balancing energy intake with expenditure, can be assessed without disturbance using drone imagery.

Q: Wow, sounds really cool. But how do the images provide information on body condition? Can a photo tell you how much a walrus weighs?
Karyn: Great question and you are right, it’s a bit more complicated. We first had to determine the relationship between actual body mass, length, and width of a walrus to what can be measured in a drone image. And that is a big part of this paper: developing that relationship with walruses in human care. We are so thankful for our zoo partners because without their collaboration and access to walruses in human care, we would not have been able to develop this approach.
Tony: The study we just completed examined the relationship between aerial imagery and the body mass of walruses at six zoos and aquariums (Indianapolis Zoo, Point Defiance Zoo, SeaWorld San Diego, and SeaWorld Orlando), Belgium (Pairi Daiza), and Germany (Hagenbeck Zoo). Results showed that measurements from aerial images were reliable predictors of body mass, allowing researchers to estimate the body mass of wild walruses using drone survey data. So, using drone imagery to monitor body condition is a breakthrough for walrus research and monitoring. This approach is simple and relies on partnership with Alaska Native communities that depend on walruses. The USGS would be unable to gather this monitoring data without the help of Native hunting families.

Q: Sounds like those partnerships were critical to making this work happen. What’s next?
Karyn: Well, early assessments of drone imagery suggest that over 200 Pacific walruses are appropriately positioned to be measured in a single image, which should allow us to measure about 7,000 animals within the herd over the course of a haulout. During 2024, we collected the first two dozen aerial surveys in partnership with Alaskan Native managers to begin laying the groundwork to monitor walruses over the coming decades. With the pace of ecological change increasing in the Arctic, there is growing demand for tools that can track the health of marine species. We feel that this study contributes to the USGS mission of developing approaches for tracking the health of Department of the Interior-managed resources, particularly reproductive-age female and juvenile Pacific walrus—key segments of the population that are most susceptible to the effects of these changes.




Sounds from a large herd of walruses resting on Alaskan shores of the Chukchi Sea
Deep full barks and calls of individual walruses near the edge of the herd are audible over a continuous rhythmic humming sound that arises from the calls of tens of thousands of walruses from deeper within the herd. Waves can be heard as they crash onto shore and slides up the beach before retreating.
Walrus Research

This is B-roll video collected during the fall of 2024 on the Alaskan shores of the Chukchi Sea.
This is B-roll video collected during the fall of 2024 on the Alaskan shores of the Chukchi Sea.
Sounds from a large herd of walruses resting on Alaskan shores of the Chukchi Sea recorded. Deep full barks and calls of individual walruses near the edge of the herd are audible over a continuous rhythmic humming sound that arises from the calls of tens of thousands of walrsues from deeper within the herd.
Sounds from a large herd of walruses resting on Alaskan shores of the Chukchi Sea recorded. Deep full barks and calls of individual walruses near the edge of the herd are audible over a continuous rhythmic humming sound that arises from the calls of tens of thousands of walrsues from deeper within the herd.
This is B-roll video collected during the fall of 2024 on the Alaskan shores of the Chukchi Sea.
This is B-roll video collected during the fall of 2024 on the Alaskan shores of the Chukchi Sea.
Comparison of the body area of walruses in human care in two positions (head up and flat) used for estimating body mass.
Comparison of the body area of walruses in human care in two positions (head up and flat) used for estimating body mass.

An adult female walrus being positioned by marine mammal trainers at SeaWorld Orlando, Florida for measurement using aerial photographs (see camera at the top of the image). These images were taken as part of a USGS study in collaboration with zoos and aquaria in the United States and western Europe for validating aerial imagery as a method for monitoring the b
An adult female walrus being positioned by marine mammal trainers at SeaWorld Orlando, Florida for measurement using aerial photographs (see camera at the top of the image). These images were taken as part of a USGS study in collaboration with zoos and aquaria in the United States and western Europe for validating aerial imagery as a method for monitoring the b
Aerial view of the edge of a large walrus herd hauled out on the northwestern shores of Alaska. The image was taken using an unoccupied aerial system, commonly referred to as a survey drone that was flown to collect imagery of walruses resting on shore in 2018 and 2019 for estimating the abundance of walruses that use the U.S.
Aerial view of the edge of a large walrus herd hauled out on the northwestern shores of Alaska. The image was taken using an unoccupied aerial system, commonly referred to as a survey drone that was flown to collect imagery of walruses resting on shore in 2018 and 2019 for estimating the abundance of walruses that use the U.S.

Walruses identified as being in an appropriate position for measurement from an image collected by a USGS survey drone on September 6, 2018, at a haulout near Point Lay, Alaska.
Walruses identified as being in an appropriate position for measurement from an image collected by a USGS survey drone on September 6, 2018, at a haulout near Point Lay, Alaska.