Devon Beaver Project Project Report – April to … · Devon Beaver Project Project Report –...

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Devon Beaver Project Project Report – April to September 2011 Devon Beaver Project 6 Month Report – September 2011 1 Introduction The objective of the Devon Beaver Project is to carry out a controlled trial using European beavers in a fully enclosed area of land, extending to 2.8 hectares. The project has the following aims: To enhance the wetland habitat value of the site by using beavers as a habitat management tool To assess the impact beavers have on this characteristic Devon habitat. We will carry out baseline monitoring before introducing the beavers and then will measure changes in vegetation cover, biodiversity and water quality A view of one of the new ponds created by the beavers in their enclosure Devon Wildlife Trust (DWT) introduced a pair of European beavers in March 2011. This report outlines the progress of the project, and the impacts that the beavers are already having on their environment and the monitoring work that is ongoing.

Transcript of Devon Beaver Project Project Report – April to … · Devon Beaver Project Project Report –...

Devon Beaver Project Project Report – April to September 2011

Devon Beaver Project 6 Month Report – September 2011 1

Introduction The objective of the Devon Beaver Project is to carry out a controlled trial using European beavers in a fully enclosed area of land, extending to 2.8 hectares. The project has the following aims:

• To enhance the wetland habitat value of the site by using beavers as a habitat management tool

• To assess the impact beavers have on this characteristic Devon habitat. We will

carry out baseline monitoring before introducing the beavers and then will measure changes in vegetation cover, biodiversity and water quality

A view of one of the new ponds created by the beavers in their enclosure

Devon Wildlife Trust (DWT) introduced a pair of European beavers in March 2011. This report outlines the progress of the project, and the impacts that the beavers are already having on their environment and the monitoring work that is ongoing.

Devon Beaver Project Project Report – April to September 2011

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Monitoring the impacts of the beavers Following the construction of the enclosure and the introduction of 2 European beavers in March 2011, the science and monitoring aspects of the project have been the focus of the work during this 6 month period. The monitoring work is divided into 3 discrete areas:

1. Ecology and Habitats 2. Ecosystem Services 3. Behavioural ecology of European beaver

1. Ecology and habitats The project aims to assess the impact of the presence of European beaver on the natural processes, wetland habitats and species of the Culm Measures, in particular by

1) Understanding the Beaver’s Influence on the landscape- by mapping physical features created and changed by the beavers, such as ‘canals’, dams, ponds and trails;

2) Identifying changes in wetland habitat dynamics - by monitoring the rate of succession from Culm grassland to woodland using a variety of indicators and methods.

3) Recording visual impacts of localised changes using a network of 96 fixed point photographs covering a large proportion of the 2.8ha of the site;

4) Assessing vegetation communities - using botanical surveys to identify plant species found within the BAP Culm grassland, and the plant community (NVC) types;

5) Determining impacts on key fauna populations – including bat communities, aquatic and terrestrial invertebrate groups (including marsh fritillary, dragonflies, moths) and other species groups, including fish and amphibians.

The beavers are already having a very profound impact on their environment, and in particular on the watercourse running through the middle of the enclosure. A ‘starter pond’ and artificial beaver lodge were constructed on this watercourse for the beavers to be released into, but they immediately began engineering it and manipulating it.

They dug downwards from their lodge and appeared to create a new chamber below the level of the existing one. A new under-water entrance was also constructed which was clearly visible during the dry spring period when water levels dropped significantly in the pond (see picture, right).

Devon Beaver Project Project Report – April to September 2011

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On the watercourse itself, the beavers began constructing dams and new side-canals (below). Quite surprisingly the dams were mainly made from silt / mud dredged from the stream bed and wet woodland, reinforced with small branches.

The beavers also started to work on some of the trees surrounding the pond .

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However, during the lush growth of the summer months, the beavers appeared to be focused on grazing of herbs and rushes (below).

Detailed fauna surveys have included moths (below left) and terrestrial invertebrates (below right).

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2. Ecosystem services There is also particular interest in assessing the impact that European beavers may have on the water draining from the site, so that the provision of ecosystem services via beaver activity in the wider landscape can be considered, in particular

1) The impacts on water retention in and released from the site into the watercourses, by closely monitoring the water table and stream levels;

2) Impacts on water quality - by looking at water chemistry, aquatic invertebrates downstream, and also understanding silt retention properties of the beaver dams.

A network of water-level recorders (dip-wells) has been installed around the site to monitor the impacts of the beaver dams on water retention within this headwater wetland habitat (right).

Already the network of new ponds and canals indicates that more water is being held on the site than prior to the beavers arrival. This pond (left) has been constructed through the building of a small earth dam about 50cms high on a small stream running through the site. New side channels have subsequently formed as the water finds numerous low spots on the dam and flows in different directions, rewetting different parts of the site.

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3. Behavioural Ecology of European beaver Monitoring of the beavers themselves is being carried out by the project’s beaver consultant. A network of camera traps (see below), have been installed and different methods are being used to monitor their behaviour and health. It is hoped that over time this will allow us to develop methods to quantify field signs so that monitoring techniques for beavers in the wild can be developed. The ability to monitor the individuals on the site is also important for welfare reasons.