In a tropical island that has experienced a consequent extinction of their avifauna in the past, how can we evaluate whether an exotic bird which is already present on the island, can act as an analogue species and fulfil the niche of seed dispersal?
How to evaluate the pros and cons of implementing the system of analogue species given that the bird also disperses invasive exotic seeds and competes with native birds?
Make sure you see the long 2015 paper on trophic rewilding. Go to the url below and then do an internal search for "seed". At least this will give you the state of the discussion, including the tortoise analog for dodo on Mauritius. But your particular question sounds fraught with an order of magnitude more tradeoffs: very difficult.
http://www.pnas.org/content/early/2015/10/23/1502556112.full.pdf
Equivalent seed dispersal effectiveness for a plant imply:
- equivalent seed germination rate/survivorship
- seed shadow, dispersal distance
- same secondary dispersors
If you can compare with your native (probably extinct species) good for you!
A major reason that tortoise analogs have not been controversial is that they are easy to remove if anything goes wrong. This does not apply to birds! I agree with David's reply above, but in Mauritius I think that any native/alien comparison will be difficult, since the native frugivrous birds are mostly extinct or very rare.
Dear all,
Thank you very much for your answers.
Dear Mr Corlett,
As you pointed correctly, the native avifauna of Mauritius is either very rare or extinct, hence giving us no option than relying on the exotic birds to fulfil the niche of seed dispersal.
I am trying to find out whether we can use an exotic bird as an ecological analogue to promote seed dispersal of native plants. Could you advice how to proceed experimentally?
Thank you.
Best regards.
If you have captive native and exotic birds, I would compare maximum gape widths, and gut passage times and seed germination for the same fruits. I expect, for example, that the red-whiskered bulbul will be equivalent to the Mauritius bulbul, and will also be able to disperse all the seeds dispersed by the native white-eyes. It would also be good to compare the diets of wild birds, but there may be too few native birds left to do this. At least you could look at the seeds dispersed by the RW bulbul. Presumably the pink pigeon destroys most seeds it consumes?
I agree with R. T. Corlett. You also need to make direct observations of birds in the ecosystems.
Andrew :-)
You can compare seed distributions between areas that still have indigenous avifauna with your tropical island :-)
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