Development of a population model tool to predict shooting levels of Greenland barnacle geese on Islay
Background As part of the 10-year Islay Sustainable Goose Management Strategy (ISGMS), population management has been carried out on Islay based on a previous Population Viability Analysis (PVA) (Trinder 2005, 2014). However, Scottish Natural Heritage (SNH) now wishes to update its existing populati...
| Main Authors: | , , , , |
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| Other Authors: | , , , , , , |
| Format: | Report |
| Language: | English |
| Published: |
Inverness
2020
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| Subjects: | |
| Online Access: | http://hdl.handle.net/1893/33185 https://www.nature.scot/naturescot-research-report-1039-development-population-model-tool-predict-shooting-levels-greenland http://dspace.stir.ac.uk/bitstream/1893/33185/1/SNHRR1039.pdf |
| Summary: | Background As part of the 10-year Islay Sustainable Goose Management Strategy (ISGMS), population management has been carried out on Islay based on a previous Population Viability Analysis (PVA) (Trinder 2005, 2014). However, Scottish Natural Heritage (SNH) now wishes to update its existing population model because intended Greenland barnacle geese (GBG) reductions during the first years of the ISGMS have proved difficult to achieve. Here, we present a new modelling approach combining data on population size, land-use, climate, and shooting effort that will enable shooting bags to be derived under quantified levels of uncertainty. Main findings - The Greenland barnacle goose (GBG) population on Islay has shown a logistic growth rate. After an initial rapid increase in population size, the population growth rate has declined. - The recent (e.g. 2003-2015) GBG Islay population fluctuates around 45,000 (± 4,082 standard deviation) individuals - The population model (PM) developed here accurately predicts the average winter population of GBG on Islay measured between November and March (inclusive) in the absence of culling on Islay. - Based on previous work, the PM assumes that both climate and the area of improved grassland (AIG) are strong predictors of the size of the GBG population on Islay. Similarly, the PM requires the inclusion of shooting bags implemented on Greenland and Iceland to estimate future population trends. Thus, all of the above (i.e. climate, AIG and shooting bags) need to be updated in the model to obtain future population predictions. - Integration of the PM into the Generalised Management Strategy Evaluation (GMSE) framework provides a tool for forecasting the dynamics of geese based on management targets and maximum allowed shooting bags. - The PM used here to inform shooting bags via the GMSE approach provides a good fit to available historic data and performs better than using the population count from the previous year alone, or using a simpler logistic growth model. - For the PM-GMSE ... |
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