Wildlife reintroductions raise a number of challenging issues for conservationists. We are quite good at understanding the biology and ecology of our focal species when we study them in established populations. We have much less power and confidence however when it comes to predicting the impact of that same species in a novel context, which is often the case in reintroductions. Yes, it may be a native species to the area in question, but it might also have been absent for a long time. In that time the playing field will have likely changed, as have the players; the prey, the predators, and the people.

This week, I have been responding to disgruntled murmurings in Pont Rhyd y Groes that the newly established pine martens Martes martes are impacting on red kites Milvus milvus, once themselves rare, now fully restored and thriving in Wales. Some of the farmers within the release area have been noticing empty nests where they are used to seeing breeding birds, and they know pine martens were released in the vicinity. Firstly, I chased up an old ringing veteran who estimated the kite population in Ceredigion to be eight thousand birds – very robust, and certainly no longer vulnerable in terms of numbers. I then had a chat with an RSPB warden on the Black Isle in Scotland, where red kites and pine martens coexist. Marten density on the Isle is relatively high, as is the productivity of the red kites. In twenty years of monitoring the kites he had not seen a nest raided by a pine marten.

So it seems from an ecological perspective we probably don’t have an issue; kites are abundant in Ceredigion, and if nest predation by martens does occur, it is a rare event. This is not an ecological issue though, it is a social one. When the kites were very rare there was an enormous effort by multiple partners to galvanise land owners and farmers into protecting their local birds. This effort worked very well; farmers guarded their kites, and a culture of protection developed around the birds – something local farmers are rightly proud of, thirty years on. It has however created a potential conservation issues for us with an interest in reestablishing the marten, an arboreal predator. We have no evidence of the martens predating kite nests locally – the missing birds might simply have not returned this spring, or bred elsewhere. But for the land owners, it’s easy to put two and two together, and cast the marten as the villain. From our perspective as ecologists, a couple of predated nests may not be a problem, but for the land owner who retains a sense of responsibility as a kite guardian, one nest is too many. Data, numbers, and ecological theory are, from my experience, unlikely to work here; we will have to appeal directly to the  land owners values to try and contemporize the narrative of the two species, before the issue festers into resentment.

–  David Bavin