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Background
The Hair Snag system is needed for wildlife research in the field by partners of the San Diego Zoo and the Institute for Conservation Research. The device collects hair from an animal and isolates the sample such that it contains DNA from only one individual. The hair samples are used to conduct eDNA analysis and to better understand how individual animals move in their environment. The device is intended to be used on Andean Bears, Jaguars and many other species in the future.
Project Objectives
High Priority Objectives
Create mechanism that traps and isolates hair samples with little to no electrical power
Second Priority Objectives
Maximize durability over time in the field
Minimize effort to reset the trap
Easily manufacturable and low cost (buildable by researchers)
Ideally purely mechanical
Tertiary Objectives
Electrical sensing modality design
Ultra-low power communications device design
Other Constraints and Issues
Must be field-ready (from arctic to rainforest climates, animal-proof)
Must be non-invasive
Deployment time: weeks or more
Mitigate false triggering
WOW Design Solution
Ability to work in places all over the world with various types of animals
Reconfigurable / applicable for any species
Inclusion of signal indicating the trap has been triggered
Able to be cleaned so you reliably know there is no contamination from previous trials
Additional Requirements given by animal field researchers
Solution to prevent insects from entering the tube.
Amazonian leafcutter ants are very destructive.
Mitigate risk of animal damaging/destroying device.
Avoid startling animal when device is sampling.
Loud noises could induce an aggressive response in Andean Bears.
Animals will be less likely to return to device if startled.
Collect 10 hairs and 3 follicles per sample ideally
Ability to be sterilized
Current Devices
Fig. 1 "Use of scented hair snares to detect ocelots." (1 December 2005). Photograph. John L. Weaver, Peggy Wood, David Paetkau, and Linda L. Laack. Wildlife Society Bulletin. https://doi.org/10.2193/0091-7648(2005)33[1384:UOSHST]2.0.CO;2
Current hair snag devices mainly consist of rough surfaces that animal hair sticks to when an animal interacts with it. These stationary surfaces are often made of barbed wire or thick carpet which the animals rub up against. These devices have no way of isolating hair samples from different individuals, resulting in mixed samples that provide uncertainty in DNA testing. Our goal is to solve this problem with a new type of hair snag.
Design
Our final design consists of a PVC pipe isolation spring, sampling spring, foam block/dowel and door. When an animal presses against the sampling spring, it slips off the hook and the coils of the spring close around the animals hair. This is what collects the sample. The isolation spring pulls the sampling spring into the tube for isolation. The sampling spring must fully close around the hair to ensure a good sample, so the friction between the tube and foam slows that isolation phase enough to sample. To better protect the sample, a door on a hinge is attached to the foam/dowel and is pulled up to close the tube. This will prevent insects and smaller animals from damaging or contaminating the sample. The door also ensures the foam/dowel does not extend beyond the opening of the tube. After the device is triggered, the sampling spring can be removed and brought into a lab environment for testing where the hairs will be removed and the spring sterilized with alcohol.
More information on our final design and previous prototypes can be found by clicking the design button below or clicking the final design tab.
Performance
Our goal was to collect at least 10 hairs and 3 hair follicles per sample. Hair strands contain mitochondrial DNA whereas the follicles contain nuclear DNA. Mitochondrial DNA can be used to determine species but nuclear DNA is needed for any further genetic testing. We began with testing our prototypes on a rabbit pelt. This was adequate as a proof of concept but we were unsure of how well it live animals as this hide was processed before purchase. We were later able to test on frozen and fresh euthanized raccoons provided by San Diego Wildlife Removal. In our tests we were able to collect much more than 10 hairs per sample, and were able to meet the 3 follicle requirement. Live animal testing will be conducted by our sponsors later this summer.
Data, figures, test procedure and images can be found by clicking the test results button below or in the reports drop down menu.
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