Radar for tracking marine birds

[Taylor Brown]

Hi everyone,

I know this isn't directly Motus-related so apologies if my email is against the guidelines.

I have considered using Motus for this project, but I want to try and capture the movements of hundreds or thousands of birds, and using Motus is just not possible for me in this case, as much as I would love to. 

I would like to see what the overall movement patterns are of Atlantic Puffins as they fledge from an island breeding colony in Newfoundland (they fledge at night - so visual surveys are not possible). The best way I can think of to do this is to install a marine radar near or on the colony. The colony island is about 2-3 km offshore (and not exactly flat). 

Now, I have never watched a puffin fledge but I can imagine that although they may head straight for the water at first (?), they probably take flight shortly thereafter and fly low above the water surface, as the adults do when they are out and about (there isn't much literature on what exactly puffins do when they fledge). Phil Taylor has informed me that if they do move in this way, close to the water's surface, it may be difficult to capture them on radar without too much clutter from waves and surface reflection, and I would have to put the radar at sea level instead of pointed downward at the water's surface, but still might not get good results.

Does anyone here have experience using radar to track broad movements of marine birds (especially flying close to the water's surface), who can comment on the feasibility of what I'm proposing? Any thoughts / information / ideas are welcome. Feel free to email me here or at taylo...@trentu.ca

Thanks!

Taylor Brown

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Taylor Brown, B.Sc., M.Sc.

PhD Student, Environmental and Life Sciences

Trent University

[Corey Wotring]

Taylor,

Good morning. While not an expert on RADAR I do have some experience with aviation based RADAR systems.  Your contact is correct in regard to the antenna placement. an antenna placed high, would give you more range, but would certainly introduce problems with high angle reflections from the water's surface. An antenna array placed closer to the surface will give the opportunity to give some separation between your intended targets and the water. One property of RADAR is it's resolution, which is how well it can discriminate between objects that are close together in proximity. This is a function of the system's beam width. The wider the beam width of the signal, the more likely two objects (birds and waves) located within that width would be confused as one. So a narrower beam width would possibly be able to discriminate between a wave and bird. Now, you might not be able to tell the difference between a wave and bird on the return in terms of size of the return, but with some experience in studying the returns, you could potentially differentiate based on the relative movement.  Fishermen use their shipboard radar to track sea birds because they know where the fish are at. So I think there's a good chance you could get this to work. I'll be if you go to the harbor a fisherman might just show you how to do it. I did find this document giving a little info about the subject.  https://sora.unm.edu/sites/default/files/journals/nab/v038n06/p00982-p00983.pdf   Good luck! I'm interested to know what you come up with.

Regards,

Corey Wotring

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[René Janssen]

Hi Taylor,

Did you tried already thermal imagine? I expect this could be give also a clue what is going on. 

René

Op wo 14 okt. 2020 om 14:03 schreef Corey Wotring <cmwo...@gmail.com>:

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[Jeff Buler]

Hi Taylor,

I have some experience working with mobile radars too, but would defer to Phil's recommendations. You might be able to place the radar below the colony at sea level and, with a typical marine radar t-bar antenna, find a tilt angle that samples just close enough to wave height so as to reduce clutter from waves. The t-bar antennas usually have a 12 degree tall beam, so you would be able to sample the airspace above the waves with the wide beam, but have short detection range (maybe 1-2km). Alternatively, you could attach a parabolic antenna (2-3 degree beam width) and aim it just above the waves and get farther detection range (because of the gain from the narrower beam), but have narrower sampled heights.

You might also consider using a thermal IR camera trained on the colony to see birds departing burrows. I have used a FLIR camera with a 6 degree beam width that can detect a robin sized bird from 1km away that cost $8k. I pointed it vertically to monitor traffic rates of migrating birds flying overhead. FLIR has wider angle cameras that may work better for your application and are much cheaper than a radar.

Best,

Jeff 

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Jeffrey Buler, Ph.D.

Associate Professor of Wildlife Ecology

Aeroecology Lab

Department of Entomology and Wildlife Ecology

University of Delaware

246 Townsend Hall

Newark, DE, USA 19716

Office: 302-831-1306