A bird on the list is worth how many in the bush?
Protected areas underpin many global conservation efforts, but do they work? Despite significant investment in protected area networks, it is often unclear whether national parks and other protected areas are effective in maintaining their biodiversity values. Long-term monitoring data are critical for determining whether protected areas are able to achieve their objectives. The problem is that in most cases, these long-term data ‘officially’ do not exist. The good news is that even though ‘official’ data sets collected by scientists often don’t exist, ‘unofficial’ observations made by keen ‘amateur’ naturalists are sometimes readily available. Can these citizen-science records shed any light on the effectiveness of protected areas? We examined the value of bird lists in assessing impact in Australia’s Wet Tropics and found they can make a real contribution (Barnes et al., in press).
‘Impact’ is the difference in the total value of an asset caused by an action. It can also be thought of as return on investment.
In the case of protected areas and biodiversity values, impact is the difference in the state of the biodiversity value that can be attributed to the protected area and any management therein. To evaluate impact, we need to compare change in the protected areas to the change that would have occurred in the value in the absence of the protected area.
Ideally, protected area performance would be quantified using a standardised BACI (Before-After-Control-Impact) monitoring program that includes a number of control regions. The problem is that ‘protection’ has usually been established well before resources are dedicated to biological monitoring. Such data are therefore rarely available from standard monitoring programs.
So if ‘official’ data is lacking, are there any other data around that might be of use? As it happens, places of high natural value are often a magnet for nature lovers, especially birdwatchers. And birdwatchers are good list makers – meaning that many places for which there are no official data have an abundance of unofficial data in the form of bird lists.
Not only are there often many bird lists available for some areas, they are often the only source available if we go back a couple of decades.
Previously, ecologists have treated citizen-collected scientific data with some reservation. Part of this is based on the reliability of observations made by amateur naturalists and the non-standard nature in which the data are recorded. However, it turns out the data that bird nerds painstakingly enter and share for the pure love of birds, can be incredibly valuable!
What’s on the list?
The aim of our analysis was to evaluate the contribution of protected areas to the conservation of endemic birds. We did this by comparing abundance and trends in birds within and outside of protected areas in the Australian Wet Tropics in Queensland. Our data were non-standardised volunteer collected bird surveys (bird lists) and the approach we used involved List Length Analysis. Similar to other studies (Szabo et al., 2010) we estimated trends in species populations with a Bayesian logistic regression to infer bird presence from bird lists.
List Length Analysis uses presence-only data and assumes that the length of a species list is a reasonable measure of how likely any bird is to be found. In theory, if a species is declining, its relative abundance compared to that of other species within the community will also decline, and therefore a greater amount of effort is required to find it. Hence, if a species is declining, it will appear less frequently on bird lists of the same length as time passes.
By adapting List Length Analysis for impact evaluation, where formal data collection is too expensive or time consuming, it may still be possible to inform decision-making if citizen-collected species list data are available. This has exciting implications for places where there are lots of bird nerds but limited funds for surveying – like, for instance, the Brazilian Atlantic Forest.
Our analysis targeted 21 bird focal species. Overall, we found that 18 of these have been stable since 1998. Sixteen were more likely to be found within the Wet Tropic protected areas, two were more likely to be recorded outside, and three showed little difference. Except for one endemic species, there was no difference in trends in prevalence between protected and unprotected areas. These results suggest that for the majority of species, protected areas may contain better habitat than unprotected areas, but birds inside protected areas are not significantly better off through time than birds outside protected areas, as long as forest outside protected areas remains intact.
Substantial portions of the Wet Tropics were adversely affected by two severe tropical cyclones during the study period, and resultant local
declines have been reported for some of the species assessed (notably golden and tooth-billed bowerbirds). Though the confidence intervals for these species are broad, it is promising that sharp declines have not been noted, especially for golden bowerbirds, which also are among the most vulnerable species in the Wet Tropics under climate change. Further, given dire predictions for a number of Wet Tropics endemic species in the face of climate change, it is good to know that no major declines are yet evident overall!
Our findings have direct implications for the monitoring and management of the Wet Tropics World Heritage Area and other landscape-scale management approaches. Since there is no marginal benefit of protected areas, our results potentially reflect the effectiveness of landscape management. Maintaining intact rainforest may be enough to ensure the conservation of viable populations of range-restricted birds in the Queensland wet tropics in the medium term! We would however recommend targeting more systematic monitoring towards species with high uncertainty, small sample size, indicated declines and differences between protected and unprotected areas. These include the golden bowerbird, fernwren, Atherton scrubwren, and satin bowerbird.
If the persistence of birds in Australia can be achieved with simple protection of habitat, Category I – IV protected areas are therefore likely to become more important: legally, they are currently the only areas in Australia that are protected from mining and logging in perpetuity (Nature Conservation Act 1992, Qld), at least in most jurisdictions.
Unfortunately, recent relaxation of land clearing laws (see http:// concernedqldscientists.wordpress.com/) that were intended to prevent broad-scale vegetation clearing in Queensland are likely to result in increased land use conversion, so the actions of the WTMA and local landholders to continue their good work in the face of these challenges will be vital.
At a minimum, a list contains the names of observed species, the date and a geographic location of the observations. Date can be an exact day or just the year in case of long term datasets. Similarly, geographic location can be broad if we are looking at the ‘big picture’. However, if people have been making lists of the same group of species (as in bird lists) for the same place over a long time, those simple lists can provide us with a lot of valuable information.
The impact of these observations on our understanding of bird trends and behaviours, for example, can be massive, and only likely to increase in the future.
And, when it comes to bird lists, these days there are heaps of tools and organisations to help you maintain and share your list. In terms of Australia, check out Eremaea eBird
Want to try it?
We have developed an R package (the beta version is freely available online: http://www.edg.org.au/free-tools/listlength.html), along with a guide that explains how to get your data in shape, what you will need to undertake, and how to use the package. We’re happy to help too, so let us know if you have any questions.
More info: Megan Barnes email@example.com
Barnes M, JK Szabo, WK Morris & H Possingham (In Press). Evaluating protected area effectiveness using bird lists in the Australian Wet Tropics. Diversity and Distributions.
Szabo J, P Vesk, P Baxter & HP Possingham (2010). Regional avian species declines estimated from volunteer-collected long-term data using List Length Analysis. Ecological Applications 20: 2157–2169. And see Decision Point #38