Page 126 - Alderney Regional Environmental Assessment of Renewable Energy: Environmental Report

Alderney Regional Environmental Assessment of Renewable Energy:
Environmental Report
(ABP Research & Consultancy Ltd, 2000). Over 12 separate visits, disturbance by construction
activities (which involved piling and reclamation of part of the foreshore) was observed on 3
occasions and in each case birds were disturbed over a small area and then rapidly resettled
within the zone of disturbance (i.e. they did not leave the area). More recently, surveys of the
birds around the Immingham Outer Harbour in the Humber (using the same methods) have
also indicated that such disturbance events are limited and are often attributable to non-Port
related activities such as the presence of Peregrine Falcons or walkers on the mudflat
(ABPmer, 2010b).
The ABP Teignmouth Quay Development also estimated an approximate zone within which
birds may be affected by disturbance from construction works (piling and dredging) to be
typically about 200m (ABPmer, 2002). The startling effects of sudden noise were quantified,
based on published research, by the Environment Agency for the Humber Estuary Tidal
Defences scheme. It was concluded that a sudden noise in the region of 80 dB appears to
elicit a flight response in waders up to 250m from the source, with levels below this of
approximately 70 dB causing flight or anxiety behaviour in some species.
Drilling/piling activity during construction of the tidal turbine devices and offshore substations
could disrupt seabird foraging and directly affect the senses of species diving underwater for
prey. Seabirds hunt visually underwater, but evidence on land suggests they may also have
acute hearing, and thus marine noise could disorientate and upset foraging rhythms, and
potentially cause permanent damage to hearing.
With respect to vessel movements, the presence of boats may cause an increase in noise and
vibration levels which could result in disturbance to / displacement of seabirds. Species such
as Red-throated Divers and Sandwich Terns are considered particularly sensitive to shipping
noise, although it is important to recognise the noise source levels of shipping is considerably
smaller than for piling.
The sensitivity of birds to airborne noise during all phases is considered to be low given their
ability to habituate to continual noises (e.g. piling). The sensitivity of species to underwater
marine noise is considered to be moderate for diving species and low for surface-feeding
species. There is limited data on this issue, however, as described under visual disturbance,
survey work on the SeaGen Strangford Lough project has shown that while some fine scale
displacement of birds in the immediate vicinity of the device occurred, the overall numbers in
the area have remained stable (Royal Haskoning, 2011).
Noise disturbance during construction will generally only be short-term. Given the unconfined
nature of the area, any birds that do pass through the area will be able to easily move away
from any temporary noise disturbance and return once the disturbance has ceased. Exposure
to change is considered to be medium during construction elements of the Draft Plan if
percussive piling is required, resulting in an insignificant to minor adverse impact for
terrestrial and surface-feeding birds, and insignificant to moderate adverse for diving birds.
Exposure to change is considered to be low for all other phases and elements of the Draft Plan,
resulting in an insignificant to minor adverse impact.
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