Hello!
I am designing an experiment to test mimetic seed dispersal by frugivorous birds in Port Elizabeth, South Africa.
We are planning present a number of seeds, still on their branches, to the birds. We either want to stick the branches through small holes in a platform (into a bowl of water?), or use clamps to display them.
The study site is a very windy place, so we are concerned that a) the seeds will fly away and b) the motion sensitive cameras will react to the branches moving in the background. Placing the cameras at the top would possibly solve that issue, unless the cafeterias are hanging up and moved by the wind themselves.
Are there any other, more suitable ways to build a cafeteria? Should we have perches for the birds?
Any tips are welcome!
Thank you.
Why not mount mobile phone -sized cameras (just the lens, not a whole camera) on the branches supplying the seeds so they move with the branch in the wind? If you reduce the depth of field to the length of the branches, background interference should be decreased.
Unless the birds commonly perch while feeding, I would have thought keeping things as similar to "real life" as possible is preferable. Perches might alter the preference towards hard-to-extract but more profitable seeds, or away from easy-to-gain but low-payoff food sources.
Seeds flying away(falling off in the breeze) is probably an unavoidable complication that you will have to factor into your estimates of consumption.
Andrew Paul McKenzie Pegman, thank you! Would it be unnatural for a frugivorous bird, though, to be feeding of a flat food trap? Will a perch make it more natural?
Matthew Wheal, thank you for your elaborate answer. We are working with a Bushnell - and will try fiddle around with it to decrease depth. That is a very good advice!
I was thinking to attach the seeds (on their branches) right to the perch. That should then hopefully eliminate the possibility of the birds preferring one seed over the other. We are working with frugivorous, arboreal birds mostly, and as far as I am concerned they perch while feeding.
I suppose I was thinking of perches as structures in front of the seed-bearing branches. In typical circumstance though, the birds would alight on the branch itself, or at least the same tree/bush/tussock.
No single experimental design is perfect, so as long as you can justify your design to your supervisor (and presumably external reviewers later on), go ahead with the best solution you can come up with. Consult a statistician to check your design can be tested adequately, your local bird experts (the amateurs or local bird club might have some suggestions too), and maybe some animal behaviourists (I'm guessing you're studying ecology more than ethology).
A final idea: perhaps a wildlife photographer from a documentary production company might have some ideas for the camera setup?
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