Here on Bitsofscience.org we try to keep things simple. CCD is bad. Invasive species are bad. But sometimes complex reality forces you to consider more pragmatic views. Or at least that’s what two Princeton researchers would argue.

Endemic pollinators are always cuter still. Picture of native New Zealand short-tailed bats enjoying a nocturnal meal of nectar. Credit: lead author David Pattemore.

Their publication in Proceeding of the Royal Society B is titled “Invasive rats and recent colonist birds partially compensate for the loss of endemic New Zealand pollinators” – and that about makes the point.

If however you gave conservationists a red button pressing which would wipe out the New Zealand populations of good old Rattus rattus* little would they hesitate.

In an experiment the Princeton researchers compared North Island (surrendered to the rats) to a small offshore island still harbouring endemic vertebrate pollinators and found that the invasive species (also including the silvereye – a bird that recently hopped over from Australia and South Island) had taken over pollinating jobs, maintaining three investigated indigenous plant species.

Confused? In the end it’s all down to the same rule of thumb: in ecology disturbance is always bad – and that also applies to the disturbance of a new-found equilibrium. What is also no different: the more species we transport from the one side of the globe to the other, the higher the chances of witnessing ecosystem collapse. But perhaps we’re keeping things too simple here…

[*) Did you know this black rat the Europeans shipped across the globe is in fact invasive to Europe too? When we celebrate Christmas we commemorate a time when the continent was still (for another hundred years) rattus-free. (Bethlehem wasn’t by the way.)]

© Rolf Schuttenhelm | www.bitsofscience.org