Seabird Abstracts

Development of MSFD Indicators, Baselines and Target for

the Annual breeding Success of Kittiwakes in the UK (2012)

Cook ASCP, Dadam D & Robinson RA (2014) JNCC Report 538, ISSN 0963 8901

  1. The Marine Strategy Framework Directive (MSFD) has been developed with the objective of achieving Good Environmental Status (GES) across Europe's marine environment by 2020. Seabirds have long been proposed as valuable indicators of the health of the marine environment.
  2. One of the definitions of GES is that "the distribution and abundance of species should be in line with prevailing physiographic, geographic and climatic conditions". However, seabirds are typically long-lived, with expected lifespans of several decades, so changes in abundance often show a marked lag following any change in environmental drivers. Demographic parameters, like breeding success, are often more responsive to environmental changes than changes in population size. Seabird breeding success has been shown to be closely linked to food quality and availability. Consequently, tracking breeding success over a broad spatial scale would provide a valuable tool with which monitor the effect of anthropogenic activities on the wider marine environment.
  3. Kittiwakes (Rissa tridactyla) are considered to be highly sensitive to changes in food supplies as they show little ability to exploit alternative fish species if their main prey is unavailable; therefore they are an excellent candidate for an indicator species of sandeel availability. Previous work by Frederiksen et al (2004, 2007) found kittiwake breeding success in eastern Scotland and eastern England to be significantly negatively correlated with local mean winter Sea Surface Temperature (SST) during February and March of the previous year.
  4. Here, we develop this approach to derive an indicator of kittiwake breeding success at colonies around the UK based on data held by the Seabird Monitoring Programme (SMP), separately for the Greater North Sea (GNS) and Celtic Seas (CS) sub-regions of the OSPAR Convention for the Protection of the Marine Environment of the North-East Atlantic. We then conduct a trial assessment of the proposed target ("Annual breeding success is not significantly different, statistically, from the level expected in the prevailing climatic conditions in five years out of six") for these indicators.
  5. Kittiwake breeding success data were available from the Seabird Monitoring Programme (SMP) for the period 1986-2010. Twenty-nine colonies were identified as having sufficient data for the GNS sub-region, and ten for the CS sub-region.
  6. Baseline breeding success was calculated using generalised linear mixed-effect models fitted with either a single fixed slope, i.e. we assumed differences in the relationship between breeding success and SST between colonies were primarily due to sampling variation or a colony-specific random slope to take into account colony-specific differences in the relationship between breeding success and SST at each colony.
  7. The fixed-slope model and the random-slope model produced different baseline and target breeding success. The fixed-slope model was more conservative than the random-slope model and thus resulted in a greater number of colonies failing to reach the target in a given year and lower proportion of years in which the target breeding success was met in each colony.
  8. The two sub-regions did not differ to a great extent in the percentage of years in which the targets were met, but within the GNS there was a much greater likelihood in failure among colonies in Orkney and, especially, Shetland, than elsewhere on the eastern side of Britain.
  9. Since 2000 there has been a gradual decline in the proportion of colonies contributing to the SMP database that are achieving the target breeding success, irrespective of which model is used. This decline appears to be similar in the two regions and it suggests that pressures acting in the marine environment continue to be severe.
  10. The annual breeding success indicator for the GNS should be equal or greater than 93% in any given year, and the indicator for CS should provisionally be considered as 96% success until more reliable data for the sub-region are collected. The indicator should be presented on an annual basis in the form of a map illustrating success per each colony in each year and in respect to the long-term trend.



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