Beaver behaviour during high water regarding burrows in levees
Author(s) |
F.P.W. van den Berg
|
A. Natarajan
Publication type | rapport Deltares
The beaver population has grown exponentially since its reintroduction in the Netherlands. The beaver digs their burrows in soil structures, including levees. This weakens the levees and causes them to lose their strength, endangering the safety of the levee. The beaver digs into the levee, especially when the water in the river rises rapidly. Various measures are being taken to prevent the beaver from digging into the levee. To determine effective measures to prevent the beaver from digging into the levee, it is necessary to know the behaviour of the beaver during high water. This case study uses an agent-based model to study this behaviour of the beaver.
The used conditions (variables) in this case study are windchill, duration of the high water, level of high water, and competitors as other beavers/ badgers (the red arrows as shown in the image below). The variables mentioned can be manipulated, changed or turned off. Once the model is run, by pressing ‘go’ (as seen in the image below), the beavers move around the model world until they find a target location or get worn out of energy. Following this, the probability of digging is calculated based on the number of beavers that have dug into their choice of a safe place during high water divided by the total number of beavers in the study. This case study shows that it is possible to create an agent-based model with the assumed conditions to predict the behaviour of beavers during high water. We believe that agent-based modelling is useful in accounting for real-time decision-making amongst the beaver families, incorporating independent behaviour traits, and also testing out several combinations of parameters. We have also provided some recommendations for improving the model such as greater complexity in the landscape features such as vegetation, natural inundations or wooded areas, variability in beavers—age, number of individuals, family sizes, more emphasis on territory and their ability to dig underwater that a future version can use as a starting point. This starting point for more complex agent-based models can provide more insight into their behaviour and provide way for better measures for averting them from digging into levees.