My interests and current research revolve around understanding invasive non-native species and how they affect the Scottish environment and biodiversity.
Optimising the long-term control of invasive American mink from catchment to coast: how many mink is too many?
PhD aim:
How many is too many? This question is the backbone of any invasive animal species control project when eradication in the near-future might not be possible, as time, money and resources are limited, meaning that a residual number of the invader remain. This is especially the case with highly mobile and widespread invasive species such as the American mink. Because of that, control programmes such as the Scottish Invasive Species Initiative aim to run continuously and cover as much ground as possible, since stopping control could lead to the reinvasion of the species.
I know that might sound pessimistic, but what if we did not have to remove every single individual to succeed in protecting native biodiversity? It could be that, if we keep the invader population at a low enough number, their damage to affected species could become negligible and allow native species to recover. That number is the “too many mink” threshold and we do not currently know where it lies nor what would be needed to reach and maintain it. The main goal of my research is to solve this mystery.
PhD objectives:
How do we find that threshold? First, we need to go back to the goal of the control project: protect the endemic species from the impact of the invasive American mink. Impact usually means a change in native populations, such as reducing their abundance. Thus, to find the threshold we need to describe and understand the relationship between the number of mink and their impact on native species, e.g., water vole. I aim to try and answer the following questions:
- How were the water voles doing before, during and after the mink invasion and control? I am collating all known past water vole surveys and records in Scotland into one big database to see how their distribution in Scotland has changed over time. To find out their present ranges, I am surveying many waterways in northern Scotland looking for signs that indicate their presence. These signs consist of active burrows on the riverbanks, latrines and droppings, and fresh vegetation clippings or, if lucky, sighting the mighty beasts themselves.
- What numbers of mink would be needed to cause the declines and recoveries seen? Now that we know about the vole side of the equation, to find the now infamous threshold we need to know how many mink there are/were and how these could have impacted the distribution of water voles. How do we know how many mink are/were really present or how many there could be? In reality, it is impossible to know for certain as some areas might not have been under control and, even if controlled, some mink might never be trapped or detected! Nonetheless, this can be attempted thanks to all the information gathered when operating mink rafts or/traps over the years by all volunteers and project and partner staff from the Scottish Invasive Species Initiative – as well as the efforts from previous American mink control projects. With such data, I will use statistical models to estimate mink numbers over time and different control intensity levels in an area. With the mink numbers and the water vole data, I will aim to uncover the relationship between American mink numbers and their impact on water voles so we can finally know how many mink is too many and what we need to do to get there.
Contact details:
Email: [email protected]
Twitter: @abonetb