1. Introduction/ Current Status
Barn Owl is a characteristic and much loved farmland bird. Like
so many species of farmland bird, it has undergone a major decline
due loss of feeding habitat resulting from changes in agricultural
practices. Losses of nesting sites due to demolition and decay of
farm buildings; barn conversions and loss of hollow trees have further
contributed to this decline.
information is now available on the ecological (feeding habitat
and nest site) requirements of the Barn Owl and organisations such
as the Hawk and Owl Trust (HOT) have shown that local populations
can often be enhanced considerably through changes in habitat management
combined with the provision of suitable nest sites. There is considerable
potential to increase the Barn Owl population of Sussex.
a popular species whose fragile population is influenced by a range
of factors not entirely addressed by Sussex Habitat Action Plans,
the Barn Owl is one of only a few species to have its own Species
Action Plan (SAP) for Sussex. It is appreciated that much conservation
effort is already underway in Sussex to improve the fortunes of
this bird. However, due to the many and varied factors impacting
on our Barn Owl population it is considered that the preparation
of a SAP is the best way of addressing all of these issues at the
action plan also promotes the Barn Owl as a flagship species for
conservation management being a good indicator of ecologically rich
b) Habitat requirements
Owls are birds of low-lying open farmland and woodland edge. They
feed on small mammals, predominantly the short-tailed vole, but
also mice, shrews and small rats. They require extensive areas of
prey-rich habitat, usually rough, ungrazed or lightly grazed tussocky
grassland in the form of whole fields, field margins, parkland,
orchard and newly planted plantation. A breeding pair requires at
least 50 hectares (120 acres) of rough grassland over which to hunt.
Temporary ley grassland, closely grazed fields and cereal crops
do not provide good hunting grounds. However, the Barn Owl can survive
well alongside modern intensive farming if linear strips of rough
grass are present in the form of wide field margins and banks of
rivers and drainage ditches. Where Barn Owls are dependant on linear
grasslands, a breeding pair will require at least 15 km (9 miles)
of 6 metre (20 ft) wide field margin or river bank within a 3 km
radius of the nest site. For example, a 100 ha farm with ten 10
ha fields each bounded by rough grassland margins (Shawyer 1996).
sedentary, Barn Owls require suitable habitat within their home
range throughout the year. Localised conditions, such as winter
flooding, can have devastating effects. However, since young generally
disperse up to about 20 km recolonisation is likely to occur in
time unless populations are severely fragmented.
Nesting and roosting requirements
a significant proportion of Barn Owls in Sussex breed in nest boxes
in barns, trees, and mounted on poles. Natural cavities in trees
are also used. Other nest sites in Sussex have included church towers,
castles, water towers, a disused railway bridge and a crevice in
a chalk cliff.
day-time roost sites are another important requirement. Trees and
secluded farm buildings are commonly used.
Current status/distribution in Europe, UK & Sussex
The Barn Owl is considered to be a Species of European Conservation
Concern having an unfavourable conservation status in Europe (SPEC
Category 3). Since the 1950s it has declined throughout much of
its European range. The main strongholds are Spain, France, Germany,
Italy and the UK (Shawyer In Tucker & Heath 1997).
In the 50 years between 1932 and 1982 the Barn Owl population of
the British Isles fell by 70% (Shawyer 1987). However, by 1997 Project
Barn Owl, a joint HOT/BTO (British Trust for Ornithology) research
project, revealed that the national population had stabilised at
about 4,000 pairs (Toms, Crick & Shawyer 2000).
the1982-85 Barn Owl Survey, the HOT developed a National Conservation
(Action) Plan for the Barn Owl, 1988-2008. This highlighted the
importance of river valleys, which held over 80 % of the total breeding
population in the UK.
A similar decline is thought to have occurred in Sussex, with an
estimated population of 400 pairs in 1932 falling to 140 pairs by
1985 (Shawyer 1998). The decline may have been halted in Sussex,
probably within the last 10 years, due to more favourable habitat
management (through Countryside Stewardship, etc) and greatly increased
provision of nest boxes. However, the Sussex population remains
fragile and fragmented.
W. Rother, Arun, Adur, Ouse and E. Rother river valleys of Sussex
were considered to be nationally important in the HOT's National
Conservation Plan for the Barn Owl, 1988-2008.
A detailed review of the species in Sussex is given in The Birds
of Sussex (James 1996). Further information is published by The
Sussex Ornithological Society (SOS) in the annual Sussex Bird Reports.
1. Distribution map of the Barn Owl in Sussex, based on records
collated for The Birds of Sussex (1988-1992 distribution shown as
solid dots and pre-1988 records as open circles). Reproduced with
kind permission from The Sussex Ornithological Society.
Barn Owls are protected under Schedule 1 of the Wildlife and Countryside
Act, 1981, making it illegal to kill, injure or take a Barn Owl,
or to destroy its eggs. It is also an offence to disturb a Barn
Owl, except under licence, 'while it is building a nest or is in,
on or near a nest that is containing eggs or young' or to 'disturb
dependent young of such a bird'. The release of captive-bred Barn
Owls into the wild was formerly permitted under licence but is now
47 of Planning Policy Guidance Note 9 (PPG9) on Nature Conservation
establishes that the presence of a Protected Species, such as Barn
Owl, is a material consideration when a local planning authority
is considering a development proposal, which would be likely to
result in harm to the species or its habitat.
a species listed in Appendix II of the Berne Convention, member
states are required to take special measures to conserve the Barn
Owl. It is also included in Appendix II of the EU Birds Directive,
The Barn Owl is included in Red Data Birds in Britain (Batten et
al, 1990), a book that catalogues those species, which are rare,
or in danger of extinction. More recently it was placed on the amber
list in The Population Status of Birds in the U.K. (Anon 2002) on
account of :
i) Moderate decline (25-49%) in UK breeding population or range
over the previous 25 years and
ii) Species with an unfavourable conservation status in Europe (SPEC
2 & 3: A Species of European Conservation Concern).
the UK Biodiversity Steering Group Report (1995), the Barn Owl is
listed as globally threatened being on the "Long List"
(Now replaced by the list of Species of Nature Conservation Concern).
assessing its own priorities for conservation action, English Nature
identified Barn Owl as "High Priority, List 2" (Brown
& Grice 1993).
Current Factors Causing Loss or Decline [top]
Owl populations can be subject to marked annual fluctuations related
to natural causes, notably cycles in vole abundance (which affects
brood sizes and fledging success), incidence of winter snow cover,
periods of heavy or continuous rainfall and flooding (all of which
can affect food availability). However, it is the following threats
to the population in the long-term, which are of real concern:
Loss of feeding habitat (rough grassland) due to agricultural change
Agricultural intensification is thought to have been the major factor
responsible for the decline of the Barn Owl. Factors have included
a reduction in the area of rough grassland, a switch from hay to
silage and loss of hedgerows and headlands. Changes in farming techniques
have led to a reduction in both the extent and quality of prey-rich
habitat for hunting.
since about the early 1990s agricultural intensification has largely
been halted in Sussex and measures such as Countryside Stewardship
and set-aside are resulting in improved habitat for Barn Owls. Habitat
Action Plans (HAPs), notably the Floodplain Grassland HAP for Sussex,
identify many actions to reverse the earlier trends of habitat loss.
has also contributed to the loss of some areas of rough grassland.
This is likely to remain an issue with the demand for new housing
Loss of nest & roost sites
Loss of nest sites due to the demolition of farm buildings and barn
conversions continues to be a major problem in Sussex. Local Authority
Development Control Officers have an important role to play.
blocking off of entrances to church towers, barns and other buildings,
usually to exclude pigeons and Jackdaws, has reduced the availability
of such buildings as roost and nest sites. It is thought that this
is not a significant issue in Sussex, though there are several known
examples where traditional nest sites have been lost in this manner
in recent years.
Sussex has lost many of its mature farmland trees through Dutch
Elm disease and the storms of 1987, 1991 and 2000. This has led
to the reduced availability of large tree cavities and the loss
of long-established nest sites.
Road & rail mortality
Shawyer & Dixon (In Prep.) estimate that 3,650 Barn Owls are
killed annually on dual carriageway Trunk Roads and Motorways in
England. This represents a significant toll on the breeding population.
Studies have also shown that casualties tend to be concentrated
in specific localities or "accident black spots", such
as where roads cross river valleys.
monitoring of animal fatalities on a 10 mile stretch of the A27
west of Chichester by Graham Roberts between the opening of the
road in October 1988 until April 2002 included six dead Barn Owls.
It is also known that within a couple of years of the A27 opening,
Barn Owls had disappeared from at least one regular breeding site
close to the road.
Shawyer of the Hawk & Owl Trust has received as many as 25 reports
per annum of Barn Owl road fatalities in Sussex (pers. com). Eight
road deaths were reported to the Sussex Ornithological Society in
2000 (Roberts 2001). However, the actual number could be far greater
than both of these totals.
seems likely that road mortalities will have increased in recent
decades in Sussex, as elsewhere, as the length of trunk road and
speeds of traffic have risen. Road deaths may be an important factor
in limiting the population and may also account for the absence
of Barn Owls in localised areas of otherwise favourable habitat.
Second generation anticoagulant rodenticides
The widespread use of second generation anticoagulant rodenticides
is currently of concern. Research has shown that a significant proportion
of British Barn Owls contain measurable levels of these rodenticides
in their tissues.
Drowning in water troughs
Farmland water troughs can provide convenient drinking and bathing
sites for Barn Owls. However, if they fall in, particularly when
the water level is low, their soft plumage waterlogs very quickly
and they are liable to drown. Such fatalities are not uncommon.
E.g. Three reported to the Sussex Ornithological Society in 2000
Collision with wire fences & power lines
Flying into overhead wires and fence wires represents 5% of all
mortality (Shawyer 1998).
Climate change including increased flooding
Widespread flooding can result in the drowning of large communities
of small mammals across the flood plain with severe consequences
for Barn Owls. Much conservation effort is being concentrated in
river valleys but on the edge of flood plains, where possible.
long term increase in snowfall could have a big impact through increased
Loss of rough grassland through urbanisation has already been mentioned.
In certain localities, increased levels of human disturbance, especially
around nesting and roosting sites, may also be a problem.