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Additional protection against disturbance whilst nesting
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Barn Owls are included in Schedule One of the Wildlife & Countryside Act 1981 which affords them protection against disturbance whilst nesting. Specifically, under Part 1, Section 1 (5) it is an offence intentionally or recklessly to:
- Disturb any wild bird included in Schedule 1 while it is building a nest or is in, on or near a nest containing eggs or young.
- Disturb dependent young of such a bird.
Since Barn Owls do not ‘build’ a nest, their protection against disturbance is generally considered to commence as soon as the first egg is laid, although it could be argued that the shredding of pellets or the making of a shallow scrape in preparation for egg laying constitutes nest ‘building’. Protection against disturbance ends when the last young owl becomes independent (or dies). It is important to note that Barn Owl young continue to be dependent on their parents long after they have fledged. Typically they fledge at 8–10 weeks old and become independent at 11–14 weeks old, sometimes later. Whilst dependent, the young are legally protected against disturbance no matter where they are. Their temporary daytime roosts can easily be up to 500 m from the nest and they are likely to venture even further within the period of dependency.
Adult Barn Owls are effectively only protected against disturbance while they are in or near a nest containing eggs or young. ‘Near’ is open to interpretation, but normally means within the same building or just outside, and within 30 m in the case of a tree nest (Ramsden & Ramsden, 1995, 2002). However, the extent of potential disturbance depends largely on the extent of deviation from the norm; a major building project involving large numbers of workmen, vehicles and machinery generating a great deal of noise 100 m from a previously isolated, quiet nest site might potentially be disturbing, whereas a similar development the same distance from a Barn Owl nest in a busy farm complex might not be.
‘Intentional’ or ‘reckless’ disturbance and the need for awareness
Under the original W&C Act 1981, disturbance was only an offence if it was ‘intentional’ (i.e. the offender knew the species was present and breeding and that what they were about to do would be disturbing, but they subsequently did it anyway, and the birds were disturbed as a result). Under Part 1 (4) 2 (c) the prosecutors also had to prove that the disturbance could ‘reasonably have been avoided’. Convictions were hard to secure until the Countryside and Rights of Way (CROW) Act 2000 amended the W&C Act 1981 and introduced the concept of recklessness*. This made it much easier to prosecute for:
- Any activity that involves deliberately taking an unnacceptable risk.
- Failing to notice or not considering an obvious risk, which results in disturbance.
* As defined by Regina v Caldwell 1982
In summary, therefore: if you are involved in a situation where something potentially disturbing is planned, and if it is reasonable to expect you to know that Barn Owls might be present and breeding, and if you fail to check (or get a suitably licensed person to check) then you may be deemed ‘reckless’ and found guilty of an offence*
* This interpretation was approved by English Nature’s legal department for the publication Barn Owls on Site (Ramsden & Ramsden, 2002).
Whether or not it is ‘reasonable to expect you to know’ that Barn Owls may be present and breeding depends on your involvement with the site in question and/or your involvement in the process that leads to or results in the potentially disturbing activity. Anyone with a professional involvement (e.g. land managers, land agents, planning officers, architects, builders, tree surgeons, ecologists etc.) could be expected to know. It is essential to bear in mind that Barn Owls have been recorded nesting in every month of the year.
What constitutes disturbance?
Some people take the view that Barn Owls are shy and easily stressed and that any disturbance will therefore cause them to abandon their nest or leave an area for good. Others consider them to be almost ‘bombproof’, taking no notice of people or machinery nearby, even when they are nesting. Such seemingly conflicting points of view can in fact both be regarded as correct – exactly what constitutes ‘disturbance’ is highly variable.
Disturbance is not related to noise type, noise level, lighting, movement, vibration or the close proximity of a person. What disturbs Barn Owls is the unexpected. Thus normal, frequent and regular human, animal or mechanical activity within the same building as an occupied nest may not be disturbing to the birds if they are used to it. Conversely, any unexpected prolonged and/or noisy work within the building or close by may be extremely disturbing to the birds and pose a major threat to breeding success.
Causing a bird to fly repeatedly from its nest, or stay away when it would otherwise be incubating eggs or brooding young, would constitute disturbance, as would blocking or drastically changing a bird’s normal access into its nest. Flushing a recently fledged (dependent) young Barn Owl from its roost and thereby forcing it to fly in daylight, or preventing its free access to its natal site, could also constitute disturbance.
Although there are a great many influences, there are two which mainly determine how an individual Barn Owl will react in terms of its continued site occupancy. These are:
- How well established the bird is at the site.
- What it is already used to.
Three additional factors can strongly influence how adult Barn Owls in their nest will react to disturbance and the chances of nest abandonment. These are:
- The bodily condition of the birds (how well they are doing)
- The height of the nest above ground level
- How well hidden the birds feel they are.
Birds that have only recently occupied a site and have not yet become accustomed to nearby noises are more sensitive to disturbance than birds that have been there a long time and heard it all before. Nesting birds that are underweight in a low exposed nest are more sensitive to disturbance than birds in tip-top condition that are safely tucked away in a secure (elevated and enclosed) nest cavity.
Sensitivity to disturbance also varies in relation to the bird’s annual cycle. During the early parts of the breeding cycle (courtship and pre-laying stage) sensitivity can be high, particularly amongst individuals who are underweight or have not bred at the site before. Sensitivity can remain high throughout egg laying, incubation and brooding, but generally reduces once the young are old enough to be left uncovered. However, even at this late stage, disturbance must be kept to a minimum, especially during the evening and at night, so the adults can repeatedly deliver food items to the nest.
Juvenile Barn Owls in post-fledging dispersal can also be sensitive to disturbance when trying out new daytime roost sites. This dispersal phase generally occurs from August to November, but because these young birds are by then independent, they have no legal protection against disturbance.
Legal aspects of building works or tree felling/surgery
Where planning consent has been obtained, the contravention of wildlife legislation during the development phase is largely prevented by the requirement for pre-development wildlife surveys and the implementation of pro-biodiversity planning policies. In spite of this, things do occasionally go wrong and nestling birds are sometimes discovered during development. Tree felling operations, crown reduction, pollarding etc. can also cause disturbance to nesting birds and/or their dependent young; to proceed with development or tree work once an active nest is discovered would clearly be illegal.
Where the protection of breeding Barn Owls has called a temporary halt to the development, the delay will not normally exceed four months in total. Where development work awaits the completion of a breeding cycle, a nest inspection should be carried out by a licence holder before work is resumed. There may be some scope for phasing works at larger developments involving more than one structure though advice should always be sought from an ecological consultant. The potential for disturbance must be assessed, bearing in mind the stage of the nesting cycle in combination with the location, nature and extent of any material evidence elsewhere, and the location, nature and extent of the actual works. Remember that the activity itself is not the disturbing factor to Barn Owls, but rather its unexpectedness.
The best precaution for minimising the likelihood of disturbing breeding Barn Owls is to avoid works commencing between 1st March and 31st August, as most breeding cycles fall within this period. At sites where works commence before 1st March it is still possible that the birds could move into the development site and start to nest in spite of all the noise and activity. However, it can be argued that, in doing so, the birds have demonstrated their tolerance of the development. In such cases the immediate nest area should be declared a no-go zone and the existing noise and activity levels should not be allowed to increase significantly.
A far better option is to make alternative provision for the birds a minimum of 30 days before works are due to commence, in the hope that they will nest there instead. If there is any doubt about the status of Barn Owls at the site, it is advisable to adopt a precautionary approach, assume that birds are present and nesting and avoid doing anything that may constitute disturbance.
Remember that if you fail to consider the risk, then you are being reckless.
There is more information on this topic in the Barn Owl Conservation Handbook