Dog eat dog: species interactions hold the key to how climate change affects nature

Guest post by Richard Bradbury, RSPB Centre for Conservation Science

Recently, I’ve been involved in a great collaboration between partners from across the Cambridge Conservation Initiative (CCI). Led by the British Trust for Ornithology, the first findings of the project have just been published online here in the journal Global Change Biology. The recent IPCC report clearly shows that climate change is having wide-ranging impacts on wildlife. In this paper, we were interested to know exactly how climate change might be affecting species –is it primarily through direct effects on species (eg succumbing to extreme cold, drought or heat) or is it more complicated than that? The answer to this question will be really important for figuring out how we might try to help species to adapt.

To find out, the team reviewed almost 150 published studies of climatic impacts on natural populations. Although you might expect that most species are responding directly to climatic changes, the majority of impacts of climate change actually occur through altered interactions between species within an ecosystem. One caveat to the result is that the vast majority of the information comes from the temperate and polar zones. There is a pronounced lack of information from the tropics, where most species’ occur – a real wake-up call for more climate impacts monitoring and research in these areas.

Each species shares an ecosystem with other species, some of which it might eat, and others that might eat or compete with it. It appears that it is changes to the populations or activity of these other species which caused many of the impacts observed. The higher up the food chain, the more likely that climate change had its impact via these indirect mechanisms, rather than a more direct impact of, for instance, changed temperature or extreme rainfall events.

For example, Arctic fox populations have been affected not only by expanding red fox populations but also by declining lemming populations, the latter being linked to changes in snow cover. 

Arctic Fox. By Algkalv (Own work) [CC-BY-3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons

In the UK, the golden plover is affected because hotter, drier conditions dry out the peat in which the larvae of its cranefly prey live, killing them and therefore reducing the food supply for the plover chicks. Of course, that counts as a direct effect on the craneflies!

Golden plover in the breeding season. By Chris Gomersall (RSPB images)

A cranefly – key food for golden plover and many other species of birds. Their larvae line in the ground and can die in dry conditions. By Matthew Carroll.

So, how does this help in the fight to help species adapt to the changes that are already in the system because of climate change? Well, conservation action already includes managing interactions between species, such as controlling invasive species or reducing predation risk, so we already have some of the conservation tools that we are going to need. This gives hope that we can help vulnerable species to adapt to some of the effects of climate change. For example, in the UK uplands, we can restore degraded peatland habitats to boost cranefly populations, and increase their resilience to climate change, and so maintaining food for golden plovers. The long term success of these conservation responses will be linked to our efforts to contain climate change through reducing greenhouse gas emissions, and so limit its impacts.  And as climate change increases the conservation effort required, we’ll need appropriate conservation funding to rise to the challenge.

So saving nature in a changing climate will need a big collaborative effort, across adaptation and mitigation, and across science, conservation, politics and society. The continued growth of the CCI, and the recent launch of the RSPB Centre for Conservation Science, will make an important contribution to this effort - it’s a really exciting time to be a scientist at RSPB!