National flying-fox monitoring program frequently asked questions
Monitoring is the process of collecting data on the abundance of a species and its distribution. It is a critical activity in biodiversity conservation because it provides insight into the status of a species and over time provides an indication into population trends and other ecological factors. This information is necessary to assess the kind of management required and to measure the effectiveness of management.
Monitoring of flying-foxes is even more important because two species, the grey-headed flying-fox and the spectacled flying-fox, are listed as threatened under the Commonwealth Environmental Protection and Biodiversity Conservation Act 1999 (EPBC Act) and relevant state legislation. The results of the program will also help inform responses to public concerns about the impact of flyingfoxes on industry, agriculture and public health, including any potential Hendra outbreaks.
How is the monitoring being conducted?
The monitoring of any species must be specifically designed according to the species' ecology and behaviour. It must also be designed to match the resources available. The large size of flying-fox aggregations (or camps) and their extreme mobility mean that flying-fox monitoring is not a straightforward task.
The National Flying-fox Monitoring Program (NFFMP) is designed to collect data on the abundance and distribution of flying-foxes in eastern Australia. Counts will be conducted at all known camps in the range of the grey-headed flying-fox - which stretches from Adelaide through to Bundaberg - and the spectacled flying-fox - which is between Ingham and Cooktown in far north Queensland. Counts will also be carried out at as many little-red and black flying-fox camps in these regions as resources allow. The method employed has been chosen as it is:
- appropriate for the spatial ecology and behaviour of flying-foxes, and
- allows estimation of the errors associated with counting animals.
This last point is critical. All monitoring methods have errors and without quantifying these, it is impossible to determine the degree of confidence that can be placed in any population estimate.
At small camps, usually 1000 individuals or fewer, flying-foxes are counted directly. At larger camps it isn't possible to count every flying-fox and it becomes necessary to use a sampling method. The method being used is point-based distance sampling. Essentially, this method estimates flying-fox density and can be used to estimate of the number of animals in a camp based on the area of that camp. On-the-ground counters move through a camp or around a camp's perimeter and at random points they count every flying-fox they can see and the distance of each flying-fox or cluster of flying-foxes from where they are standing. This distance is subsequently used to estimate the probability of detecting a flying-fox. This probability, otherwise known as detection error, is an important contributor to monitoring error and its quantification is critical to estimating the reliability of monitoring results.
Why is monitoring being conducted this way?
This method has been chosen because it provides a scientifically robust estimate that is underpinned by well-researched statistical analysis. Critically, this analysis includes estimation of the reliability of the estimates produced. Research by several groups here in Australia has shown that when this method is applied to flying-foxes, it performs better than alternatives, including the traditional fly-out counts, and it is simpler to implement.
Who is doing the counting?
The NFFMP is a collaboration between the Australian Government, South Australian, Victorian, New South Wales, Australian Capital Territory and Queensland governments, the CSIRO, and local governments and volunteers.
The participating state and territory environment departments coordinate counts in their jurisdiction by identifying camps, maintaining a database of their locations, and assigning counters for those camps. The state coordinators also collect data sheets and forward these on to CSIRO for data management and analysis.
Counts are performed by agency staff in South Australia, Victoria and the Australian Capital Territory. In New South Wales and Queensland, counts are performed by agency staff, local government staff and volunteers.
Can this data be used to change listing of the species?
Decisions about the status of a species - that is, which threat category it is listed under - are based on a range of criteria. These include the size of a species' population, changes in the population size over time, the extent of its distribution, changes in distribution, the number of populations, and current and future threats to the species and its habitat.
For the listing of a species under the Commonwealth EPBC Act, advice is provided to the Minister by a selected group of scientists - the Threatened Species Scientific Committee (TSSC). The TSSC undertakes a rigorous assessment of all available information against the criteria when providing advice on the threat status of a species. The data being collected through the NFFMP, abundance and distribution, could contribute to a re-assessment of the threat status of flying-foxes as would other relevant information. It will be some years before populations and trends can be estimated reliably enough through the NFFMP to inform such an assessment.
Is it possible to count all flying-fox camps?
There are always going to be camps and flying-foxes that are missed. This is a common problem in ecological monitoring. In the NFFMP this could be because the camps are not known to anyone, because the camps are not known to the monitoring program or because, despite being known, it is not practical or feasible to count the camps.
All possible efforts will be made to include and count all known camps, but this may not always be possible. For example, camps in remote locations may be difficult to access. As a consequence, research that complements the monitoring program will estimate the effect of missing camps on the reliability of the population estimate.
Can the counts be compared with the counts conducted prior to 2006?
The counts conducted prior to 2006 were conducted at different times of the year, using different methods and were conducted over different areas. These differences make direct comparisons between the numbers produced by the two sets of counts difficult. Research under the NFFMP will investigate how reliable comparisons between the NFFMP and these previous counts are.