DALS WILDLIFE SITE { WILDLIFE OF NORTHERN ENGLAND}

WILDLIFE OF NORTHERN ENGLAND

Mammal status UK Text courtesy of Natural England .org 

Water Vole , Image courtesy of Pedro  CC BY-SA 3.0 license.File:Water Vole on Itchen Navigation.JPG

Report findings.

This report presents the first comprehensive review of the status of British mammal populations for over 20 years. The population size, range size, temporal trends and future prospects of Britain’s 58 terrestrial mammals are assessed.

The review presents the most up-to-date assessment of population size and status for the 58 terrestrial mammals in Britain. The report highlights an urgent requirement for more research to assess population densities in key habitats, and to assess the percentage of potentially suitable habitat where a given species actually occurs: at present, uncertainty levels are unacceptably high.

Red Squirrel

Image courtesy of Dirk Thierfelder  CC BY-SA 2.5 license.Sciurus vulgaris May 2006.jpg

Red Squirrel

The red squirrel occurs in both conifer and broadleaved woodland, as well as in mixed forests and parks and gardens (Harris and Yalden, 2008). It eats a wide range of foods, but tree seeds and fruits are particularly important, followed by tree shoots, buds, flowers, berries and lichens (Moller, 1983; Gurnell et al., 2015). Woodlands with mixtures of tree seeds provide a more reliable year-to-year food supply. In mixed conifer forests, home range selection is based on the availability of seed from different species throughout the year (Lurz et al., 2000). Sitka spruce, which is widely planted in managed woodlands, has unreliable fruiting cycles, and there is a negative relationship between the proportion of Sitka spruce in woodlands and the density of red squirrels (Lurz et al., 1998).

Status ----Native.

 

Native. 
Conservation Status 
 
• IUCN Red List (GB: EN; England: [EN]; Scotland: [NT]; Wales: [EN]; Global: LC). • This species has not been assessed for Article 17 of the EU Habitats Directive. 
Species’ distribution 
A distribution map is presented in Figure 7.1a. There has been considerable recording effort in Scotland since the Saving Scotland’s Red Squirrels partnership project was launched in 2012, and particularly since the development in 2015 of an interactive website for recording. It is therefore possible to present a detailed distribution map. The gap in the species’ distribution in the Central Belt is likely to extend to the west of Glasgow and east towards Edinburgh, with only very sparse records in this region. The intensive survey effort carried out by the Saving Scotland’s Red Squirrels project suggests that this gap is real, and not an artefact of the smoothing process used to create the current distribution map. In England, 

 • IUCN Red List (GB: EN; England: [EN]; Scotland: [NT]; Wales: [EN]; Global: LC). • This species has not been assessed for Article 17 of the EU Habitats Directive. 

  There has been considerable recording effort in Scotland since the Saving Scotland’s Red Squirrels partnership project was launched in 2012, and particularly since the development in 2015 of an interactive website for recording. It is therefore possible to present a detailed distribution map. The gap in the species’ distribution in the Central Belt is likely to extend to the west of Glasgow and east towards Edinburgh, with only very sparse records in this region. The intensive survey effort carried out by the Saving Scotland’s Red Squirrels project suggests that this gap is real, and not an artefact of the smoothing process used to create the current distribution map. In England,

 

 the Red Squirrels Northern England Project has, for over 5 years, helped to stabilise red squirrel populations and enable them to spread outside their strongholds. The presence records in Surrey are from escaped captive animals and not from an established population.the Red Squirrels Northern England Project has, for over 5 years, helped to stabilise red squirrel populations and enable them to spread outside their strongholds. The presence records in Surrey are from escaped captive animals and not from an established population.

 

 As red squirrels are most likely to occur in mature woodlands, all recently planted (<10 years) and felled woodlands, as defined in the LCM2007, were removed from the analysis.

 

 

Scotland 976,000 239,000 181,000 444,000 
Wales 38,000 9,190 6,970 18,200 
Britain 1,180,000 287,000 218,000 553,000 
Coniferous woodland 
849,000 0.25 0.19 0.4 Lurz et al. (1998) 
Cartmel (2000) 
Wauters et al. (2000) 
Bryce et al. (2005) 
12 
12 
Species’ distribution 
A distribution map is presented in Figure 7.1a. There has been considerable recording effort in Scotland since the Saving Scotland’s Red Squirrels partnership project was launched in 2012, and particularly since the development in 2015 of an interactive website for recording. It is therefore possible to present a detailed distribution map. The gap in the species’ distribution in the Central Belt is likely to extend to the west of Glasgow and east towards Edinburgh, with only very sparse records in this region. The intensive survey effort carried out by the Saving Scotland’s Red Squirrels project suggests that this gap is real, and not an artefact of the smoothing process used to create the current distribution map. In England, 

Changes through time

Population size was estimated by Harris et al. (1995) to be 161,000, with 30,000 in England, 121,000 in Scotland and 10,000 in Wales in 1995. These estimates are based on the median population density of 0.55ha in both coniferous and broad-leaved woodland, which is almost three times higher than the current median density estimate. The population size in Harris et al. (1995) was adjusted for the proportion of woodland greater than 15 years old, and also for occupancy rates. These adjustments were based on expert opinion (John Gurnell, pers. obs.) and different values were used per country. The resulting total occupied area was 300,000ha, compared with 1,180,000ha in the current review.   The percentage occupancy values employed by Harris et al. (1995) were not reported, and so could not be applied in our calculations. Considering that the range size of red squirrels has also changed substantially since 1995, the final value for the area occupied could not be used, either. The area in the current estimate was, therefore, not adjusted for occupancy, and totalled 1,180,000ha of woodland within the species’ distribution. The lack of occupancy data and the consequently larger area used for the population size calculations precludes direct comparisons of population sizes between the two time periods. These differences also

 explain why the current estimates of population size appear larger than those given by Harris et al. (1995), despite the evident contraction of the geographical range of the species.  

 Nationally, there are changes between the two reviews in the estimated availability of key habitats (broad-leaved woodland and coniferous woodland), generated by a combination of true change and methodological differences, irrespective of any range change The adjusting of results to reflect more probable temporal changes in the composition of the British landscape — using differences between the 1990 and 2007 Countryside Surveys (Carey et al., 2008) — produces a population size only 4% larger than the original (and within the original confidence limits). These differences are unlikely to affect the conclusions materially.  

 

Widespread population suppression caused by squirrel pox. 
Chantrey et al. (2014) 
Negative 
Recent emergence of adenovirus. Everest et al. (2014) 
Negative 
Competition. Competition with grey squirrels for resources, leading to reduced recruitment and breeding success.  
Gurnell et al. (2004b) 
Gurnell et al. (2015b) 
 
The distributions in England and Wales are considerably more restricted than were reported by Arnold (1993; >90% loss in each country), with populations in East Anglia, the Humber Estuary, Derbyshire, Pembrokeshire, Carmarthenshire and Denbyshire having been lost, and those in Lancashire and Gwynedd significantly reduced. In Scotland, the distribution remains approximately as described by Arnold (1993). 
 
Nationally, there are changes between the two reviews in the estimated availability of key habitats (broadleaved woodland and coniferous woodland), generated by a combination of true change and methodological differences, irrespective of any range change (see Sections 2.3 and 32.3 for further details). The adjusting of results to reflect more probable temporal changes in the composition of the British landscape — using differences between the 1990 and 2007 Countryside Surveys (Carey et al., 2008) — produces a population size only 4% larger than the original (and within the original confidence limits). These differences are unlikely to affect the conclusions materially.  
 
The distributions in England and Wales are considerably more restricted than were reported by Arnold (1993; >90% loss in each country), with populations in East Anglia, the Humber Estuary, Derbyshire, Pembrokeshire, Carmarthenshire and Denbyshire having been lost, and those in Lancashire and Gwynedd significantly reduced. In Scotland, the distribution remains approximately as described by Arnold (1993). 

Grey Squirrel

Image courtesy of Beko  CC BY-SA  4.0 license

Habitat preferences

The grey squirrel lives in a wide variety of habitats, including broad-leaved forests, mixed and coniferous forests, urban and suburban areas, and parks and gardens. It feeds primarily on the nuts and seeds of trees and shrubs, but maintains a varied diet and switches to different sources of food depending on availability at different times of year (Moller, 1983). Overwinter survival, and subsequent population density, are related to food availability and the severity of winter weather (Gurnell, 1996). In urban areas, population densities increase with the level of urbanisation (Baker and Harris, 2007; see also Bonnington et al., 2014), with grey squirrels making use of anthropogenic sources of food, such as bird seed in gardens. The grey squirrel can survive in highly fragmented, functionally isolated landscapes (Stevenson-Holt et al., 2014). Its generalist foraging behaviour and ability to adapt to different habitats and food sources have aided its spread throughout Britain.

Status

None native 

IUCN Red List (GB: n/a; England: n/a; Scotland: n/a; Wales: n/a; Global: LC). • This species has not been assessed for Article 17 of the EU Habitats Directive.

 Extensive recording efforts in Scotland by the Saving Scotland’s Red Squirrels partnership project, led by the Scottish Wildlife Trust, allows the production of a detailed distribution map for Scotland. The project has confirmed a gap in the distribution of grey squirrels between Dundee and an isolated population in Aberdeen. This gap has been filled by the smoothing process used to create the current distribution maps  rather than by records in this area. The established population of grey squirrels in Aberdeen does not extend to the north coast in Aberdeenshire/Banffshire; this area contains very sparse records that are likely to be derived from occasional individuals rather than established populations.

 Species-specific methods 

 As mature woodlands provide a more suitable habitat for grey squirrels, all recently planted (<10 years) and felled woodlands, as defined in the LCM2007, were removed from the analysis (John Gurnell, pers. obs.).

 Country Area of suitable habitat (ha) 

 England 2,260,000 1,940,000 957,000 2,560,000 

 Scotland 709,000 478,000 249,000 808,000

 Wales 333,000 283,000 139,000 423,000

 Britain 3,300,000 2,700,000 1,340,000 3,790,000

Scotland 709,000 478,000 249,000 808,000 
Wales 333,000 283,000 139,000 423,000 
Britain 3,300,000 2,700,000 1,340,000 3,790,000
Population size -95%CI +95%CI 
England 2,260,000 1,940,000 957,000 2,560,000 
Scotland 709,000 478,000 249,000 808,000 
Wales 333,000 283,000 139,000 423,000 
Britain 3,300,000 2,700,000 1,340,000 3,790,000 
As mature woodlands provide a more suitable habitat for grey squirrels, all recently planted (<10 years) and felled woodlands, as defined in the LCM2007, were removed from the analysis (John Gurnell, pers. obs.). 

No percentage occupancy data were available; the population size is therefore overestimated for this species. Broadleaved woodland contributes 81% of the estimated grey squirrel population, and forms 35% of the suitable habitats within their distribution . The population density estimate for broadleaved woodland is based on 21 individual density estimates from four papers, although the most recent of these is from 2000 (Cartmel, 2000). Coniferous woodland forms 27% of suitable habitats within the geographical range ( and population densities — based on 38 estimates from four papers — are much lower in this habitat.

 There is considerable inter-annual variation in grey squirrel density, depending largely on tree seed availability. Further surveys of population density in years with different tree-seed abundance are therefore advised for all suitable habitats. Despite the removal of young (<10-year-old) coniferous woodland, much of the remaining commercial conifer forest included in the estimate is also too young to support grey squirrel populations. Also, extensive Sitka spruce plantations, which form 58% of productive coniferous woodland in Scotland (Forestry Commission, 2014), are included in the calculations despite having very low grey squirrel densities. Whilst these factors may have resulted in some overestimation of the population size, their impact will be smaller than for red squirrels because conifer woodlands in general support only low densities of grey squirrels. Nevertheless, the application of density estimates to finer scale habitat classifications may reduce this error in future assessments. 

 

 Total population size was reported as 2,520,000 in Harris et al. (1995), with 2,000,000 in England, 200,000 in Scotland and 320,000 in Wales. These calculations were based on density estimates for woodlands as well as urban areas, although the population density used for urban areas was particularly low (0.1ha-1). The methods used to estimate population size were similar to those in this review, but the relatively low reliability of our estimate, and lack of data on the percentage of occupied habitat, mean that a comparison is not advised. Population density as currently reported for broadleaved woodlands is much higher than the estimate used by Harris et al. (1995). This is most likely to be the result of within-habitat variation in population density (Peter Lurz, pers. comm.), rather than because of an actual increase in density.

 An assessment of the future prospects of the grey squirrel, in terms of whether the population size, range and habitat quality are likely to increase, decrease or remain stable. This assessment is based on the current trends, current drivers of change, and potential future drivers of change. For a full assessment of future prospects,

 Population Increase* { Trend and status.}

 

 Range Increase. The trend is for an increase in range

 

 Habitat Stable.

 *Rate of increase may slow in response to control

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