South Island robin populations have been intensively studied at two sites in the Eglinton Valley, Fiordland, since 2005 (Fig. 1). Robin numbers have increased at one site, which is under ongoing pest control, but are declining in the neighbouring site.
Effective landscape-scale pest control, which has included the first ever valley-wide aerial 1080 operation, has continued to benefit the robin population at Walker Creek. In August 2015, robin numbers here had reached the second highest level since intensive monitoring commenced in 2005 (Fig. 2).
The response of the robin population at Knobs Flat has not been as positive, with numbers appearing to stabilise at a level that is considerably lower than previously recorded. The overall trend for the period studied has been one of continued slow decline (Fig. 2).
The reasons for the different responses of these two robin populations remain unclear. Pest control at Knobs Flat only commenced in 2011, following a severe drop in numbers and subsequent slight recovery. It is possible that poor overwinter survival and continued habitat degradation through severe wind damage may be continuing to suppress population recovery to former levels at specific locations within the Eglinton Valley.
Figure 1.Location of the two robin study sites.
Figure 2. Trends over time in the robin populations at Walker Creek and Knobs Flat, Eglinton Valley.
The numbers of robins inhabiting two forest blocks within the Eglinton Valley have been monitored intensively since 2005. The data collected provide a valuable time-series for the real-time evaluation of various pest management regimes, as well as the performance of monitoring methods. Territory mapping of individually colour-banded robins and intensive searching within the two forest blocks in August (prior to nesting) enables an accurate assessment of robin abundance.
This measures is classified as a case study. Although the general trends may well apply to mainland robin populations elsewhere, caution should be used if attempting to extrapolate these results.
This measure relates to indicator 1.5.1 - Species composition and diversity.
These estimates are considered sufficiently accurate to provide an estimate of population size that would be close to that of a complete census. Population estimates derived from robin territory mapping have therefore been used as a gold standard for the assessment of trends derived from monitoring methodologies.
This measure complies with the data quality guidelines used in New Zealand’s Environmental Reporting framework.
The Department of Conservation’s (DOC’s) Outcomes Monitoring Framework provides a platform on which DOC and others can assess outcomes in a clear, structured and transparent way (Lee et al., 2005). It has been developed as a logical hierarchy that is based on broad, overarching Outcomes, beneath which are nested Outcome Objectives, Indicators, Measures and Data Elements to provide ever increasing levels of detail. The framework is scalable, as the indicators and measures remain compatible and consistent whether applied locally, regionally or nationally.
The recently updated framework provides a roadmap for gathering information to meet the specific objectives of DOC and other agencies (McGlone and Dalley, 2015). The provision of a national framework with agreed outcomes, indicators and measures supports collaboration with land management and regulatory agencies, allowing for more integrated environmental policy and ‘State of the Environment’ reporting. DOC has partially implemented a national monitoring and reporting system, whereby priority indicators and measures are routinely used to report on progress against the objectives and outcomes. This factsheet reports on a measure for the 2015/16 year.
Lee, W., McGlone, M., Wright, E., 2005. Biodiversity inventory and monitoring: A review of national and international systems and a proposed framework for future biodiversity monitoring by the Department of Conservation. Landcare Research Contract Report LC0405/122 (unpublished) for the Department of Conservation, Wellington.
McGlone, M., Dalley, J., 2015. A framework for Department of Conservation inventory and monitoring: Intermediate outcomes 1-5. Landcare Research Contract Report LC2427 (unpublished) for the Department of Conservation, Wellington.