Our analysis shows that many species are tracking changing climate by hopping from one protected area to the next, whilst in between we see a pattern of local declines as land degradation takes its toll.
The protected area network within Tanzania is providing stepping stones for savannah birds moving in response to climate and environmental changes…
Dr Colin Beale
While most of the Tanzanian National Parks were designated with the aim of protecting large mammals, much of the important biodiversity in this corner of East Africa is found among other groups, such as plants, amphibians and birds.
There has long been a debate surrounding the relative effectiveness of such reserves for these other groups, but a new study which has appeared in the journal Ecology Letters
provides evidence not only that climate-driven shifts among African birds are already occurring, but that protected areas have an important part to play in helping them cope with change.
Researchers from Queen’s University Belfast and Biomathematics and Statistics Scotland (BioSS) were involved in the study, alongside lead author Dr Colin Beale, from the Department of Biology at the University of York.
Room for debate
Tanzania has a fairly high proportion of its land protected, and arguments have arisen over the ethics of preserving so many areas when human populations are increasing rapidly and the demand for fertile farm land is growing. There are also relatively high levels of human-wildlife conflict in Tanzania. But these are not the only issues of contention.
"There is a general global debate about how well protected areas will perform as species respond to climate change," said Dr Beale in an interview with ScienceOmega.com
. "Some have worried that changing environments may see plants and animals move into new regions as they track the changing climate, possibly leaving protected areas empty of the wildlife they are designed to protect. On the other hand, there's also a view that suggests protected areas should be more resilient to such changes than other areas.
"This debate is not limited to Tanzania, but is certainly relevant as many animals respond relatively quickly to changes in environmental conditions. For example, the wildebeest migration of Serengeti is driven in part by the search for rain and green grass – if the rainfall patterns change, will the animals have to move elsewhere? Our research suggests that, at least so far, this isn't the case."
Even though the protected area network – which includes national parks and game reserves – was designed without birds in mind, Dr Beale and his colleagues believe these areas are relatively good at protecting Tanzania’s birds and are becoming ever more important. This is particularly the case as land degradation – caused by over-grazing, appropriation of land for agriculture, loss of trees, and climate change – exerts pressure elsewhere.
Citizen scientists ‘absolutely critical’
Using data gathered by the Tanzania Bird Atlas project on 139 species of savannah-based bird, Dr Beale and his colleagues compared statistics from 1960-1989 with post-2000 observations. The species under consideration included francolins, hornbills, the Rufous-tailed Weaver, Fischer’s sparrow-lark and the Pangani Longclaw.
"Recognising that Tanzania is home to some extremely important populations of birds, with little or no knowledge of distribution, movements and abundance, the Tanzania Bird Atlas project was set up to monitor distribution and seasonal movements of birds in Tanzania," explained Dr Beale. "It has been driven almost entirely by the enthusiasm and energy of our co-author, Neil Baker, and his wife Liz."
The role of hundreds of volunteers, who contributed information on the birds they spotted on their travels, was absolutely critical to the findings, which revealed that protected areas provide a buffer against extinction for bird populations in East Africa.
"Our analysis shows that many species are tracking changing climate by hopping from one protected area to the next, whilst in between we see a pattern of local declines as land degradation takes its toll," said Dr Beale.
"Many studies trying to understand how protected areas will work in the future have relied heavily on models, whereas we took an observational approach. The disadvantage of this approach, of course, is that we don't know what will happen next. Although the protected areas so far are becoming more valuable, it is still possible that bigger changes in the future may reduce their effectiveness."
Even more important in future
The study suggests that conservation efforts in the form of national parks and game reserves are paying off, and continue to be an appropriate way of combating the effects of land degradation and climate change for now as far as the Tanzanian bird community is concerned. But how might their role change in the future?
"Protected areas in Tanzania are absolutely essential for the protection of biodiversity in the region, and for the income they generate for the Tanzanian treasury through tourist numbers," Dr Beale pointed out.
"We expect that, as land is converted outside of the protected areas as human pressures grow, the protected areas will become relatively even more important. There is still a chance that they too will suffer from changes in the land around them, however, as it is becoming much harder for the many birds and animals that currently move freely into and out of the protected areas to do so."