WATER VOLES IN THE TAY WESTERN CATCHMENTS AREA
Summary
The pilot survey of Glen Lochay in 2007 highlighted a number of populations of water voles, and, although not part of the original survey protocol, it is now considered that information relating to these little animals may indeed now be the most strategically important, both to this project and to the various agencies involved, including the two national parks. Indeed, the water vole data subsequently became our main justification for going far out in to these catchments and up to higher altitudes, and such effort required the greater part of our funding to successfully complete.
Water voles were found in all three glens, but the top end of Glen Lochay, surveyed in 2007, remains the principal area of focus for this species. Very poor and prolonged weather conditions in late summer in 2008 dramatically affected the quality of data that we could collect on the Dochart system, and it is recommended that a number of sites here are revisited in 2009.
In Glen Lochay, there were 8 sightings of water voles, droppings found at 29 different locations and burrows found at an additional 35 locations.
In Glenlyon, there were two sightings of water voles, droppings found at 21 different locations and burrows at a further 30 locations. Records were distributed throughout the length of the glen.
On the Dochart, there was one sighting, droppings were recorded at only five locations, with 17 burrows located in 6 main clusters. Weather conditions severely disrupted our survey work on the Dochart.
American mink were located in all three glens in 2008. We are aware of up to 16 animals being killed on the lower Lyon and 6 in Killin. Mink were also reported at Kirkton on the Dochart and at Kenknock Farm on the Lochay in 2008, and tracks were located at various locations throughout the Dochart and on the lower Lyon.
Limitations of data
Our surveyors were essentially self-taught in finding and recording water voles in 2007, although subsequent tuition from the CNPA Water Vole officer suggested that the 2007 protocol was in fact very sound. If anything, the protocol was simplified in 2008.
In one regard, the data is actually very strong. Surveyors had reason to visit watercourses throughout the catchments for a variety of reasons, not just those where water voles were likely to be present. As a result, water vole signs were in fact located in habitat and locations in which water voles might not have been expected.
The survey was designed to record distribution of the species, not density of water voles.
There were two problems encountered in 2008:
1 The weather was extremely wet from late July onwards, and although this did not affect the Glenlyon survey, the Dochart survey was badly disrupted. The main issue was that heightened water levels would wash away droppings and burrows too would become obscured. For a significant part of the Dochart survey therefore, we were limited to recording the locations of potentially good habitat, without the presence of water vole signs to re-inforce this information.
2 Suitable water vole habitat on the Dochart and Lyon in particular was very fragmented, and water vole habitat and signs were often to be found on side streams and not on the actual watercourses that were digitized for survey work. A number of signs were recorded in areas that might not be regarded as classic habitat, but where better habitat might have been available close at hand. Trying to quantify suitable habitat therefore became increasingly problematic and simply recording those survey lengths which were themselves suitable was obviously misleading. For the Lyon and Dochart catchments therefore, we did not seek to provide the same level of habitat information as we did previously at the top half of Glen Lochay.
Glenlyon
The Glenlyon survey took place in June and July 2008, and, although there were some wetter periods in July, it is not considered that this affected the quality of survey information recorded in any way. Water voles were recorded throughout the Lyon catchment, although never in the apparent densities that occurred at the top end of Glen Lochay. The main areas of interest were in the basin below Schiehallion, above Garth Castle on Keltneyburn, to the north of Pubil at the east end of Loch Lyon, and to the west of the road at the top of the glen that crosses through to Glen Lochay. Although records were found elsewhere, significant areas of habitat where extremely rare, with the topography of the glen being completely different to the top end of the Lochay, for example. The upland corries are more effectively and naturally drained, and large swathes of flat grasslands interspersed with standing water did not really exist to any great extent. Areas of good habitat appeared to be very restricted in their extent. However, a high percentage of these habitat patches did contain water vole signs, if only from the previous year. In some areas, eg in Glen Muillin, water vole signs where recorded within an extremely small patch of suitable habitat, seemingly well detached from the next available site. The value to the species of the sub-optimal (or seemingly unsuitable) habitat became increasingly clear, otherwise such small isolated colonies could surely never sustain themselves.
A number of records were made close to the main stem of the river.
The areas above the dams at Loch Lyon and Loch an Daimh were not surveyed as it had been considered at the outset (before water voles became a consideration) that there would not be sufficient grounds for looking at these areas. Based on the 2008 survey information, there will almost certainly be water voles present above Loch Lyon, and local gamekeepers have suggested that they are also present above Loch an Daimh. It may be worthwhile surveying these areas in future but it is not considered to be a priority to do so.
Up to 16 mink were culled in the lower part of the Lyon in 2008, but no such records or indeed signs were forthcoming above the Pass of Lyon at Fortingall. However, it is considered that no co-ordinated efforts at controlling the species are made above this point, and that the regular freshets that are released on the Lyon may simply have washed away signs on a regular basis. The main stem of the Lyon was surveyed in two days in a canoe, and mink signs could easily have been missed.
Glen Lochay
The Lochay was surveyed in 2007, with the Drumchroisk burn and one tributary on the south side of the glen surveyed in 2008. The top half of Glen Lochay, above the hydro pipeline, is extremely valuable for water voles. It is an extremely grassy area, and appears to be under-grazed. It would appear that there was some sort of population explosion of all vole species up there in 2007. As well as the number of upland corries showing signs of water voles, there was potentially suitable habitat covering most of the bottom of the glen in this upper part. In summary, a very extensive, almost unbroken area of habitat suitable for the species. This was tempered to some extent in that all the small tributaries to the north of the river above the pipeline were abstracted for hydro-power with little or no evidence of compensation flow, and therefore, many potentially suitable tributaries simply did not contain any water.
All the main corries south of the river contained signs of water voles. The basin of the Drumchroisk Burn below the Tarmachan ridge proved to be a particularly active spot in 2008.
It should be noted that we only decided to record water voles as part of our survey part way through 2007 when the survey was already underway. We would anticipate that while our records north of the river portray an accurate picture of where water voles are distributed, that on the south side of the river, water voles may well be present further east than is recorded.
Glen Dochart System
About 20% of the Dochart was surveyed in 2007, with the remainder covered during late July- November in 2008. This period was extremely wet, causing us to miss a significant number of survey days and also having the effect of washing away water vole signs.
Areas of water vole habitat south of the Dochart/ Fillan/ Cononish appear to be extremely limited, and it is considered that this broad swath of ground will never be significant for the species. The topography in general simply does not allow for suitable areas of habitat to form. An area directly below Ben Lui was perhaps the only extensive area of classic water vole habitat found, where unoccupied burrows where recorded. It was however notable that water vole droppings were recorded in the upper part of the glen, in habitat that would not be considered at all suitable for the species.eg the Sitka Spruce plantation to the west of the Cononish. Water voles were recorded by the main River Fillan at Kirkton Farm, surprising in that mink where very obviously present in the same area. A limited area of habitat at the head of Kirkton Glen bordering Glen Lochay also contained water voles.
It is considered that the main areas of habitat on the Dochart lie north of the river between Auchlyne and Inverhaggernie, but the survey of these areas co-incided with the wettest period of the summer, and very few signs were recorded. Anecdotal evidence from gamekeepers in 2007 suggested that this area did indeed have a significant population of water voles at that point. Wide sweeping searches of these areas were made to see if signs could be detected on more minor watercourses, pools or ditches, but to no avail. It is recommended that the 3-4 main areas marked north of the river be re-surveyed in 2009. It is not considered that any other areas on the Dochart system are sufficiently valuable for the species to repeat the survey.
Unlike the other two glens, much of the main stems of the Dochart and especially the Fillan are extremely slow moving, and they have a very dense network of slow moving ditches leading in to them, albeit most are extremely badly choked up with vegetation. It is quite likely therefore that the valley bottom would provide a significant habitat for water voles had the apparent numbers of mink in the Dochart catchment not been so high. Except for the records at Kirkton, no water vole signs where located near the main river, although a high % of the side ditches where not included in our survey protocol. Much of this area is not classic water vole habitat, and has not been recorded as such, but it is likely that the essential components are there and that water voles would almost certainly colonize the lower part of the catchment if they were allowed to do so.
It is worth noting that as from winter 2009, there may well be no gamekeepers employed on the Dochart system, and that this therefore will have a significant bearing on how effective mink control might be undertaken.
Use for the Information Gathered
The information gathered will be used to focus attention on achieving a co-ordinated mink control programme in the upper catchments of the Tay, which will benefit a range of water fowl and fish species as well as water voles. Such a programme should be incorporated with other essential habitat and conservation work, and be a corner-stone of our idea to promote the concept of river wardens in the areas concerned. In this context, the water vole information gathered will provide a base-line on which the success or otherwise of any such mink eradication programme can be measured.
Accessing the Information
The information gathered on water voles has been passed to both the Cairngorms National Park, and to the Loch Lomond & Trossachs National Park.
Summary
The pilot survey of Glen Lochay in 2007 highlighted a number of populations of water voles, and, although not part of the original survey protocol, it is now considered that information relating to these little animals may indeed now be the most strategically important, both to this project and to the various agencies involved, including the two national parks. Indeed, the water vole data subsequently became our main justification for going far out in to these catchments and up to higher altitudes, and such effort required the greater part of our funding to successfully complete.
Water voles were found in all three glens, but the top end of Glen Lochay, surveyed in 2007, remains the principal area of focus for this species. Very poor and prolonged weather conditions in late summer in 2008 dramatically affected the quality of data that we could collect on the Dochart system, and it is recommended that a number of sites here are revisited in 2009.
In Glen Lochay, there were 8 sightings of water voles, droppings found at 29 different locations and burrows found at an additional 35 locations.
In Glenlyon, there were two sightings of water voles, droppings found at 21 different locations and burrows at a further 30 locations. Records were distributed throughout the length of the glen.
On the Dochart, there was one sighting, droppings were recorded at only five locations, with 17 burrows located in 6 main clusters. Weather conditions severely disrupted our survey work on the Dochart.
American mink were located in all three glens in 2008. We are aware of up to 16 animals being killed on the lower Lyon and 6 in Killin. Mink were also reported at Kirkton on the Dochart and at Kenknock Farm on the Lochay in 2008, and tracks were located at various locations throughout the Dochart and on the lower Lyon.
Limitations of data
Our surveyors were essentially self-taught in finding and recording water voles in 2007, although subsequent tuition from the CNPA Water Vole officer suggested that the 2007 protocol was in fact very sound. If anything, the protocol was simplified in 2008.
In one regard, the data is actually very strong. Surveyors had reason to visit watercourses throughout the catchments for a variety of reasons, not just those where water voles were likely to be present. As a result, water vole signs were in fact located in habitat and locations in which water voles might not have been expected.
The survey was designed to record distribution of the species, not density of water voles.
There were two problems encountered in 2008:
1 The weather was extremely wet from late July onwards, and although this did not affect the Glenlyon survey, the Dochart survey was badly disrupted. The main issue was that heightened water levels would wash away droppings and burrows too would become obscured. For a significant part of the Dochart survey therefore, we were limited to recording the locations of potentially good habitat, without the presence of water vole signs to re-inforce this information.
2 Suitable water vole habitat on the Dochart and Lyon in particular was very fragmented, and water vole habitat and signs were often to be found on side streams and not on the actual watercourses that were digitized for survey work. A number of signs were recorded in areas that might not be regarded as classic habitat, but where better habitat might have been available close at hand. Trying to quantify suitable habitat therefore became increasingly problematic and simply recording those survey lengths which were themselves suitable was obviously misleading. For the Lyon and Dochart catchments therefore, we did not seek to provide the same level of habitat information as we did previously at the top half of Glen Lochay.
Glenlyon
The Glenlyon survey took place in June and July 2008, and, although there were some wetter periods in July, it is not considered that this affected the quality of survey information recorded in any way. Water voles were recorded throughout the Lyon catchment, although never in the apparent densities that occurred at the top end of Glen Lochay. The main areas of interest were in the basin below Schiehallion, above Garth Castle on Keltneyburn, to the north of Pubil at the east end of Loch Lyon, and to the west of the road at the top of the glen that crosses through to Glen Lochay. Although records were found elsewhere, significant areas of habitat where extremely rare, with the topography of the glen being completely different to the top end of the Lochay, for example. The upland corries are more effectively and naturally drained, and large swathes of flat grasslands interspersed with standing water did not really exist to any great extent. Areas of good habitat appeared to be very restricted in their extent. However, a high percentage of these habitat patches did contain water vole signs, if only from the previous year. In some areas, eg in Glen Muillin, water vole signs where recorded within an extremely small patch of suitable habitat, seemingly well detached from the next available site. The value to the species of the sub-optimal (or seemingly unsuitable) habitat became increasingly clear, otherwise such small isolated colonies could surely never sustain themselves.
A number of records were made close to the main stem of the river.
The areas above the dams at Loch Lyon and Loch an Daimh were not surveyed as it had been considered at the outset (before water voles became a consideration) that there would not be sufficient grounds for looking at these areas. Based on the 2008 survey information, there will almost certainly be water voles present above Loch Lyon, and local gamekeepers have suggested that they are also present above Loch an Daimh. It may be worthwhile surveying these areas in future but it is not considered to be a priority to do so.
Up to 16 mink were culled in the lower part of the Lyon in 2008, but no such records or indeed signs were forthcoming above the Pass of Lyon at Fortingall. However, it is considered that no co-ordinated efforts at controlling the species are made above this point, and that the regular freshets that are released on the Lyon may simply have washed away signs on a regular basis. The main stem of the Lyon was surveyed in two days in a canoe, and mink signs could easily have been missed.
Glen Lochay
The Lochay was surveyed in 2007, with the Drumchroisk burn and one tributary on the south side of the glen surveyed in 2008. The top half of Glen Lochay, above the hydro pipeline, is extremely valuable for water voles. It is an extremely grassy area, and appears to be under-grazed. It would appear that there was some sort of population explosion of all vole species up there in 2007. As well as the number of upland corries showing signs of water voles, there was potentially suitable habitat covering most of the bottom of the glen in this upper part. In summary, a very extensive, almost unbroken area of habitat suitable for the species. This was tempered to some extent in that all the small tributaries to the north of the river above the pipeline were abstracted for hydro-power with little or no evidence of compensation flow, and therefore, many potentially suitable tributaries simply did not contain any water.
All the main corries south of the river contained signs of water voles. The basin of the Drumchroisk Burn below the Tarmachan ridge proved to be a particularly active spot in 2008.
It should be noted that we only decided to record water voles as part of our survey part way through 2007 when the survey was already underway. We would anticipate that while our records north of the river portray an accurate picture of where water voles are distributed, that on the south side of the river, water voles may well be present further east than is recorded.
Glen Dochart System
About 20% of the Dochart was surveyed in 2007, with the remainder covered during late July- November in 2008. This period was extremely wet, causing us to miss a significant number of survey days and also having the effect of washing away water vole signs.
Areas of water vole habitat south of the Dochart/ Fillan/ Cononish appear to be extremely limited, and it is considered that this broad swath of ground will never be significant for the species. The topography in general simply does not allow for suitable areas of habitat to form. An area directly below Ben Lui was perhaps the only extensive area of classic water vole habitat found, where unoccupied burrows where recorded. It was however notable that water vole droppings were recorded in the upper part of the glen, in habitat that would not be considered at all suitable for the species.eg the Sitka Spruce plantation to the west of the Cononish. Water voles were recorded by the main River Fillan at Kirkton Farm, surprising in that mink where very obviously present in the same area. A limited area of habitat at the head of Kirkton Glen bordering Glen Lochay also contained water voles.
It is considered that the main areas of habitat on the Dochart lie north of the river between Auchlyne and Inverhaggernie, but the survey of these areas co-incided with the wettest period of the summer, and very few signs were recorded. Anecdotal evidence from gamekeepers in 2007 suggested that this area did indeed have a significant population of water voles at that point. Wide sweeping searches of these areas were made to see if signs could be detected on more minor watercourses, pools or ditches, but to no avail. It is recommended that the 3-4 main areas marked north of the river be re-surveyed in 2009. It is not considered that any other areas on the Dochart system are sufficiently valuable for the species to repeat the survey.
Unlike the other two glens, much of the main stems of the Dochart and especially the Fillan are extremely slow moving, and they have a very dense network of slow moving ditches leading in to them, albeit most are extremely badly choked up with vegetation. It is quite likely therefore that the valley bottom would provide a significant habitat for water voles had the apparent numbers of mink in the Dochart catchment not been so high. Except for the records at Kirkton, no water vole signs where located near the main river, although a high % of the side ditches where not included in our survey protocol. Much of this area is not classic water vole habitat, and has not been recorded as such, but it is likely that the essential components are there and that water voles would almost certainly colonize the lower part of the catchment if they were allowed to do so.
It is worth noting that as from winter 2009, there may well be no gamekeepers employed on the Dochart system, and that this therefore will have a significant bearing on how effective mink control might be undertaken.
Use for the Information Gathered
The information gathered will be used to focus attention on achieving a co-ordinated mink control programme in the upper catchments of the Tay, which will benefit a range of water fowl and fish species as well as water voles. Such a programme should be incorporated with other essential habitat and conservation work, and be a corner-stone of our idea to promote the concept of river wardens in the areas concerned. In this context, the water vole information gathered will provide a base-line on which the success or otherwise of any such mink eradication programme can be measured.
Accessing the Information
The information gathered on water voles has been passed to both the Cairngorms National Park, and to the Loch Lomond & Trossachs National Park.
No comments:
Post a Comment