Birds of Welcome Bay - Dr Meg Butler - An analysis of Bird Observations in Welcome Bay
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
1/1/2020
January 2020
Birds of Welcome Bay
An analysis of Bird Observations in Welcome Bay
2018 – 2019 and comparisons with 2014 -2015
Dr Meg Butler
Analysis of Bird Observations in Welcome Bay 2018 – 2019 and a
comparison of those undertaken in 2014- 2015
1.0 Executive Summary
A comprehensive survey was undertaken between October 2018 to September 2019 and
compared with that undertaken between September 2014 and October 2015. This survey
had several objectives:
➢ to determine the number of birds which inhabited the Welcome Bay Estuary over
the past year
➢ to identify if there was a significant difference in numbers from the earlier survey
➢ to determine the type of birds and their site locations
➢ to identify if these had changed from the earlier survey
A five minute bird count was undertaken at 11 predetermined sites across Welcome Bay for
both surveys. Data was entered onto an Excel spreadsheet and the results analysed.
Conclusions and Recommendations
➢ the bird population is relatively stable across Welcome Bay with significant increases
maintained following mangrove removal in 2011
➢ an increase was seen in the local shore birds from the previous survey 2014-2015
➢ the Waitaha Salt Marsh area has been confirmed as the only roosting/resting site in
Welcome Bay not only for migratory birds but for local shore birds as well
➢ any walkway constructed near this area would be detrimental for bird life and flora
➢ this vital and important area needs ongoing care and protection
➢ ongoing mangrove seedling control is required to keep open water spaces as feeding
grounds
1
Contents
1.0 Executive Summary.................................................................................................................... 1
2.0 Introduction ............................................................................................................................... 2
3.0 Methods ..................................................................................................................................... 3
3.1 Five Minute Bird Count .............................................................................................................. 3
3.2 Session Timing............................................................................................................................ 4
3.3 Data Analysis .............................................................................................................................. 4
4.0 Results………………………………………………………………………………………………………………………………… 4
5.0 Discussion……………………………………………………………………………………………………………………………..7
6.0 Restoration of the Waitaha Saltmarsh…………………………………………………………………………………..8
7.0 Implications…………………………………………………………………………………………………………………………10
8.0 References………………………………………………………………………………………………………………………….10
9.0 Acknowledgements…………………………………………………………………………………………………………….10
10.0 Appendix 1. Sample Bird Monitoring Sheet…………………………………………………………………………11
Cover Photo: Waiting for the Whitebait to arrive - Welcome Bay
2
2.0 Introduction
The focus of this report is to document the bird life in Welcome Bay between September 2018
and October 2019 and to compare these observations with those from an earlier report
“Mangroves and Birds of Welcome Bay: The Silent War” undertaken between September
2014 to October 2015. The open waters and intertidal estuary of Welcome Bay provide a rich
supply of food resources (benthic invertebrates) to feed many hundreds of birds, particularly
during the summer months.
3.0 Methods
The same methodology was undertaken as in the previous report. For consistency the same
eleven sites around the perimeter of Welcome Bay that were identified by GPS coordinates
were repeated as observation sites. This number (11) was chosen as being sufficient to
provide statistically significant data.
Site 1 provided an overview of the southern end of Welcome Bay. All birds which could be
seen from a wide view across the tidal flats were documented. The other 10 sites had specific
view lines: Site 2: the area by Johnson Bush Reserve, which included the stream and mud flat;
Site 3: the salt marsh at the bottom of Waitaha Rd, viewing to the left of the stream; Site 4:
the saltmarsh including the view to the right of the saltmarsh; Site 5: Tye Park looking left and
across to the Maungatapu Bridge; Site 6: Tye Park High Roost area 1 to right of Bridge; Site
7: north of Tye Park to High Roost area 2 to the tree on point. These last two High Roost sites
had been identified by the Regional Council Map Oct 2013 GIS – 465594 (Set 3).
The remaining four sites were on the southern side of the Maungatapu Peninsula. Site 8 and
Site 9 were situated by adult mangrove stands; Site 8: at the Esplanade Reserve looking right
along the mangrove edge to bush on left; Site 9: Fantail Reserve looking left along the
mangroves and right across Welcome Bay. Sites 10 and Site 11 were located at Rotary Park
with differing view lines, Site 10 from the right to the point opposite and to point across to
Bay Park, and Site 11 viewing left to the Maungatapu Bridge looking down to Bay Park.
3.1 Five Minute Bird Counts
A Department of Conservation 5 Minute Bird Count form was adapted for Estuary birds. Each
site had predetermined viewing lines to ensure the same areas of Welcome Bay were viewed
consistently. Upon reaching the site the observer would wait for five minutes before
beginning the five-minute count. All Estuary and wading birds were recorded within a five-
minute time frame timed by a wristwatch.
The information collected included Station (site) number, grid references, view lines, and tide.
Categories of birds included Ducks (Mallard/Hybrid, Grey, Shelduck); Canada Geese and
Swans; Kingfishers; Shags (Black, Pied, Little and Little Black); Oyster Catchers and Stilts (Pied
Oystercatcher, Variable, Hybrid, Pied Stilt and Black Stilt); Terns; (Caspian, White Fronted,
3
Little and Fairy), Gulls; (Black Backed, Red Billed and Black Billed) Plovers; (Spur Winged, Grey
Plover and Pacific Golden) Hawks: Australasian Harrier Hawk; and other birds seen. In
addition, variables such as weather conditions and traffic noise were also recorded. This
information was then transcribed to the Five Minute Excel spreadsheet.
3.2 Session Timing
It was necessary to complete each field work session within a two-hour time window around
the low tide as the farthest point Site 7 is only accessible on the low tide.
3.3 Data Analysis
All data gathered was entered onto an Excel Spreadsheet to analyse the recent observations
and to compare this with the earlier observations.
4.0 Results
Birds were counted by species and location across the eleven sites which covered all aspects
of Welcome Bay. Approximately 829 birds were documented compared with 857 birds in the
earlier survey. Similarly, of the twenty bird species identified, nine species were migratory
birds with no new species identified in the 2018/2019 observation period. An average was
calculated for Mallard/Hybrid Ducks (38) White Faced Herons (22) and Red Billed Gulls (38),
to avoid these birds being repeatedly counted and used in the following figures. These
document the comparisons of bird species, and their locations between the 2015/2016 and
2018/2019 time frames. Figure 1 describes the bird species and number, n= 829, identified
across Welcome Bay in the 2018/1019 monitoring period.
Observed Bird Specied 2018 - 2019
80
70
60
50
numbert
40
30
20
10
0
Resident and Migratory Birds Figure 1
4
There were increases in the main resident bird species that made Welcome Bay their home,
approximately 609 compared with 456, an increase of 33% from the earlier survey. Increases
were seen in gulls both red billed and black backed, mallard/hybrid ducks, pukeko and pigeons
(common), as seen in Figure 2.
Comparison of Resident Birds 2014 - 15 and 2018-19
50
45
40
35
30
number
25
20
15
10
5
0
Figure 2
Figure 3 describes that while there was an increase in Spur Winged Plovers, and Pied Oyster Catchers
there was a slight decline in the number of Pied Stilts and Black Stilts but a major decline in the
numbers of Canadian Geese in Welcome Bay.
Comparison of Migratory Birds 2014-5 and 2018-9
140
120
100
number
80
60
40
20
0
Black Stilts Pied Stilts Spur Winged Canada Little Black Pied Oyster Shelduck Royal
Plover Geese Shag Catcher Spoonbill
Figure 3
5
Distribution of Resident and Migratory Birds across Welcome
Bay by Site Location 2018- 2019
200
180
160
140
120
Number
100
80
60
40
20
0
Site 1 Site 2 Site 3 and 4 Site 5 Site 6 Site 7 Site 8 Site 9 Site 10 and
11
Resident Birds n = 609 Migratory Birds n= 218 Figure 4
Figures 4 and 5 describe the distribution across Welcome Bay by Site location in the
observation periods of 2014-5 and 2018-9. A similar distribution pattern is observed in these
two observation periods.
Distribution of Resident and Migratory Birds by Site
Location 2014 - 2015
140
120
100
80
60
40
20
0
Site 1 Site 2 Site 3 and 4 Site 5 Site 6 Site 7 Site 8 Site 9 Site 10 and
11
Resident Birds n = 486 Migratory Birds n= 371 Figure 5
6
5.0 Discussion
This document has described the differing types and the approximate number of birds which
make Welcome Bay either their permanent home or are summer visitors over 2018-2019, and
compares this with the recent observation period of 2014-2015.
As mentioned previously the results presented are a snapshot of bird life at specific months
of the year and are an approximation only. For example, observations in both studies were
undertaken two hours around the low tide in order to facilitate access to various sites. In
addition, the high tide feeders were not documented. These birds include White Fronted
Terns, and the many types of Shags and these are regularly observed on the high tides around
Welcome Bay. Also not counted at the observation times were Royal Spoonbills who make
regular appearances in the Bay on the very low tides, and the Australian Harrier Hawk who is
a frequent visitor.
Bird numbers varied across time and were only counted at specific times. It became apparent
that the local shore birds of Welcome Bay such as the Mallard/Hybrid Ducks, White Faced
Herons and Red Billed Gulls were probably over reported as they were likely the same birds
repeatedly counted. Therefore, an average was calculated for these birds. It is also speculated
that “other” local birds such as Kingfishers could also have been repeatedly counted. The
migratory birds did not present this problem but were probably under reported, as large
flocks of these birds were observed at other times other than the observation times.
This report indicates that the bird life in Welcome Bay has been remarkably stable over the
two observation periods, and that Welcome Bay provides a rich source of food to support
large numbers of birds. However, this can only occur with constant mangrove seedling control
to keep open water spaces for birds allowing them to feed. There appears to be an increase
in numbers of the local shore birds i.e. Mallard/Hybrid Ducks, Red Billed Gulls, Pukeko and
Pigeons. The decrease seen in migratory birds was mostly due to the significant drop (87%)
in the number of Canadian Geese seen in the Bay over the summer of 2018. This is likely due
to their plundering of the sea grass bed off the Waitaha Reserve in previous years.
To avoid repetition, this report confirms the findings of the earlier report (Butler M.) by bird
species and Site locations, and their significance to bird life and activity. Both reports
identified that the Saltmarsh area (Sites 3 and 4) off Waitaha Road is the most important site
for migratory birds as well as the local birds in Welcome Bay. This important wetland area has
also been identified as supporting a significant amount of birdlife as documented in the TCC
Reserves Management Plan 2018 (page 127). The construction of any walkway near this area
would likely be detrimental to bird life and native flora.
These observations support that of (Straw P & Saintilan N 2006), who describe that most
migratory and shore birds prefer to feed on open waters of undisturbed mudflats where they
have a clear view of the approach of avian or terrestrial predators. Park (2004) indicated that
in Welcome Bay mangroves will possibly colonise the seaward edge of the saltmarsh by 5-10
meters and that the health of the saltmarsh is poor. To overcome this a restoration planting
7
programme has been undertaken to improve the health of the saltmarsh and is documented
in the following pages.
6.0 Restoration of the Waitaha Saltmarsh
Since this area was identified in 2015 as being a significant roosting/resting area for migratory
as well as shore birds the local Welcome Bay Estuary Care Group began an active restoration
programme with the impetus from Steven Park (Bay of Plenty Regional Council scientist) as
having identified this area as being ecologically “poor”. The Tauranga Regional Council has
been instrumental in providing plants, equipment and ongoing encouragement for this work.
Photo 1 was taken prior to mangrove removal in 2011 which shows that there were no open
water spaces for birds to utilise.
Photo 1 Prior to mangrove removal Photo 2 Prior to restoration
Photo 2 shows that after mangrove removal there were now open water spaces, but the
vegetation was poor.
Photo 3 Working Bee 2016 Photo 4 Working Bee 2017
Working Bees in 2016 planted over 250 native plants and in Photo 4, 50 more Ribbonwoods and Oi Oi
grasses were planted in 2017.
8Photo 5. Litter catches on outlet stream Photo 6. Natives getting well established
In 2019 Litter catches were placed on the Waiataha Stream as rubbish collectors Photo 5, and
Photo 6 shows that the recently planted natives are getting well established.
Photo 7. Photo 8.
Photo 7 shows that the Oi Oi grasses are now well established in the upper part of the stream
and Photo 8 indicates where a further 400 Oi Oi grasses will be planted in the winter of 2020
to stablise the banks of the stream.
97.0 Implications for Bird Life in Welcome Bay
There are several important implications highlighted in this report:
• bird life appears to be stable and local shore birds are increasing in numbers
• ongoing mangrove seedling control is needed to ensure open water intertidal zones
as feeding grounds for birds
• the Waitaha Saltmarsh area is identified as the most important resting/roosting site
for both migratory and local shore birds in Welcome Bay
• the construction of a walkway near this area would likely be detrimental for bird life
and undermine this restoration programme
• this fragile area needs more protection by further restoration planting, and protection
from mangrove incursion by ongoing mangrove seedling removal
• the Dept. of Conservation Five Minute Bird Count form has been shown to be easy to
use, and could be used by other Estuary Care and volunteer groups as a standard bird
monitoring form
8.0 References
Butler, M. Mangroves and Birds of Welcome Bay: The Silent War. Research Report. 2016
Park,S. (2004) Aspects of mangrove distribution and abundance in the Tauranga Harbour.
Tauranga, New Zealand: Environmental Bay of Plenty (Bay of Plenty Regional Council)
Environmental Publication No. 2004/16.
Straw,P. Saintilan,N. (2006) Loss of shorebird habitat as a result of mangrove incursion due
to sea-level rise and urbanization. Waterbirds around the World. Eds.GC Boere,CA Galbraith
and Stroud. The Stationary Office. Edinburgh UK pp 717-720.
9.0 Acknowledgements
I would like to acknowledge the help and support of all Tauranga Regional Council Estuary
Care Managers and staff with plants and materials and most of all to the cheerful volunteers
who regularly participate in clean ups and planting sessions.
1010.0 Five Minute Bird Count - Dept. of Conservation (example)
BIRD MONITORING FIELD-SHEET 1
Location Name: Grid Refs: Date:
191b Welcome Bay Road
E: 1880587 Tide:
View: in front and all directions N: 5819992
Fieldworker: Meg Butler
5-MBC Station Number: 1 Start: Finish:
Sun: Temp: Wind: Rain: Other Noise:
Species Tally Total No.
Seen* Heard*
Ducks etc
Paradise Shelduck
Mallard/Hybrid
Australasian Shoveller
Grey Duck
Teal Grey (red eye)
Canada Geese
Black Swan
Herons
White Faced Heron
Royal Spoonbill
Kingfisher
Oyster Catchers/Stilts
Pied Oystercatcher
Variable
Hybrid
Pied Stilt
Black Stilt/Hybrid
Shags
Black
Pied
Little
Little Black (group)
Terns
Caspian
White Fronted
Little
Fairy
Gulls
Black Backed
Red billed
Black billed
Plovers
Spur winged
Grey Plover
Pacific Golden
Hawk
Others
Unknown
1112
You can also read
