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Dr. Jessica Sanchez overviews Necropsy Workshop
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In November 2024, Friends of the Island Fox sponsored the 3rd "Island Fox Necropsy Workshop" in collaboration with the Santa Barbara and San Diego Zoos. This workshop was held to train island managers and field biologists to investigate island fox mortalities and determine cause of death. In this blog post, wildlife veterinarian and FIF board member, Dr. Jessica Sanchez, describes how necropsies are preformed and why they are such an important part of island fox conservation.
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Necropsy tool kit
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In the field of wildlife biology, understanding the reason animals die is an important first step to conserving populations. We must know what the problem is before we can start to address it. Tracking causes of death (AKA "mortality") also helps us learn more about the biology of a species–for example, the common diseases they get, their average life expectancy, the survival rate of their young, etc. By performing necropsies regularly on animals that die, we can: 1) learn what a normal, baseline mortality rate is and the common causes of death, and 2) more quickly detect if something abnormal is happening, such as the canine distemper outbreak on Santa Catalina Island.
The determination of cause of death is the expertise of pathologists, who dissect carcasses in what are called "necropsies" (the equivalent of a human autopsy). Epidemiologists study the patterns of disease in populations and help determine if a given mortality is expected for a population, or if something new/abnormal is happening, such as a newly introduced disease or an epidemic (higher than normal rates of disease).
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Island fox with radio-tracking collar
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On the Channel Islands, managers place radio-collars on a subset of the fox populations every year. These collars allow biologists to track animals and learn about their biology and behavior, but also to detect when they have died. The collars allow us to detect these deaths and retrieve the carcasses quickly, often from places where they would otherwise be hard to find (like deep in the woods, buried under vegetation, or even in a golden eagle nest!) Because we can retrieve these carcasses quickly, they are less likely to be degraded by the environment, giving pathologists the best chance to determine the cause of death.
Once in the pathology lab, scientists will look at the entire carcass for signs of the cause of death. They are true detectives, looking for signs of injury from being struck by a car, talon marks from a golden eagle, or pneumonia from infection. After examining the carcass visually (a "gross necropsy"), they collect tissues for microscopic examination. These tissues are stored in special chemicals that preserve the structure of the cells, so the pathologist can look at them under the microscope. This is how we identify bacterial or viral infections, abnormal protein buildup, cancers, and more. (Cancer in island foxes). They also collect swabs and blood samples to test for antibodies against disease ("serology"), use genetic material to identify pathogens like viruses and bacteria ("polymerase chain reaction" or PCR), or test for toxicants like rodenticides. For unusual or complicated cases, several experts may get involved, including virologists, immunologists, toxicologists, and epidemiologists.
Sometimes, sending a carcass off-island to a pathologist is not practical. In these cases, it is important that island biologists can perform "field necropsies" on the island. They can perform the gross necropsy and collect key samples to send off-island to the pathologist and laboratory for further investigation. These may not be as detailed as a necropsy from a pathologist, but they allow us to gather important information on cause of death and save tissues that could be important for future research.
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Dr Leslie Woods leads the workshop
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In November, twenty island biologists and researchers gathered at the Santa Barbara Zoo for training in performing necropsies. Drs. Leslie Woods (UC Davis) and Patty Gaffney (San Diego Zoo) are board certified veterinary pathologists who have worked with island foxes for decades. They led teams through performing full necropsies and collecting important tissues for further examination in the laboratory. We discussed common cause of death in island foxes and the signs to look for on gross necropsy.
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Accurately identifying sample slides
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Participants also learned about sample storage and human safety when it comes to handling blood, tissues, and chemicals. FIF and the Island Fox Conservation Working Group plan to continue workshops like this periodically to train new staff and refresh the skills of field staff who are so important for the daily monitoring of these fox populations. They are our eyes and ears out on the island, looking for any new or emerging threats to the populations.
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PPE is necessary to when working with animals that have died
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Trainings like this highlight how important long-term monitoring and surveillance is for wildlife conservation, especially for a species such as the island fox which evolved isolated on an island and is under constant risk from introduced disease and invasive species. Radio-collaring foxes is critical for us to detect mortalities ASAP so we can retrieve the carcass as quickly as possible before signs of the cause of death start to degrade. It also helps us gather baseline information on survival rates of different age classes and sexes. Performing regular necropsies, even in the absence of an outbreak or other crisis, allows us to collect an invaluable archive of health and disease information about this species. Island fox researchers have built a database from hundreds of island fox necropsies going back 25+ years, which current and future researchers can use for studies on genetics, disease, reproduction, diet, and more. (Island Fox Research)
Thank you for supporting island fox research. Your support enables FIF to host workshops like this to train future generations of biologists to protect the island fox. - Dr. Jessica Sanchez
See Dr. Jessica Sanchez in action performing an island fox health check.
A huge thank you to all those who helped facilitate this workshop:
Santa Barbara Zoo, San Diego Zoo, UC Davis and the CA Animal Health and Food Safety Lab
