Environmental Engineering Reference
In-Depth Information
South Island/New Zealand pied oystercatcher (SIPO), wrybill, banded dotterel
and pied stilt Himantopus leucocephalus were identified by the Expert Shorebird
Group as the internal migrant species of most concern and for which collision risk
modelling was necessary. It was also agreed amongst the experts that due to
difficulty in detecting smaller, faster moving shorebird species (e.g. wrybill and
banded dotterel), monitoring of SIPO should be the focus, and that the migratory
movements of this species would be used as a proxy for the movements of all other
migrating shorebirds (including international migrants). Resident shorebirds and
other bird species were dealt with separately in terms of modelling strike risk
through data obtained from surveys combined with the internal migrating shorebird
surveys and other separate line transect and point count surveys.
The use of radar for monitoring bird movements in New Zealand was still a rela-
tively novel technique in 2009. This was only the second time that radar had been
employed for this purpose in New Zealand, and the first time that it had been used to
survey an area of this extent - some 40 km long and 8 km wide. The methodologies
for monitoring the north and south-bound migrations drew on the monitoring then
carried out to date at the Taharoa C (Fuller et al. 2009 ; Fuller 2013 ) and international
best practice methodologies. However, it was necessary to refine the methodology
to ensure that data collection was optimised and addressed potential non-detection
constraints, of which there were many. For example, unlike the much smaller
Taharoa C site, where the terrain is relatively flat, the terrain at the HMR is a series
of many small valleys dissected by east-west and north-south ridges, making obser-
vations by people and radar difficult.
From summer 2009 until winter 2010 a combination of up to three radars and a
varying number of observer stations was used in order to identify the species and
flock sizes as well as the heights that migratory and resident shorebirds were taking
over and adjacent to the HMR site.
Radar was used to track the movements of birds and plot the pathways of flying
birds onto a computer screen. These tracks (trails) were then converted to GIS to
build up a composite picture of the movements of birds and their trails in an area
over time.
Three surveillance (S-band) ship radars were used to track bird movements.
The radar types and specifications used in this study were:
FURUNO 96 nautical mile, black box S-band radar (30 kW) with a 10 ft
scanner - at one site in the 2009 surveys only; and
JRC (JMA 5330-12), 96 nautical mile, black box S-band radar (30 kW) with a
12 ft scanner (230 Vac A) - at two site in the 2009 surveys and then three sites
during the 2010 surveys.
These relatively low-powered surveillance radars are able to detect individual
birds within a range of a few km and flocks of birds up to a theoretical effective
maximum coverage of 11.1 km, depending on the radar setting chosen (c.f. six
nautical miles). The surveillance radars were used to map the trajectories of all
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