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[Homepage] [uniquenorthland] [contents] [bestlinks] [Map] [Researchtopics] ASSESSMENT OF SHOREBIRD UTILISATION AT MARSDEN POINT OCTOBER 1996-NOVEMBER 1997 Carolann Wood Executive Summary: A study by Gavin Grant of the Ornithological society was made in 1994-1995of an area of intertidal flats at Marsden Point. The intention of that study was to provide information on the utilisation of the intertidal flats by shore birds at the proposed new Port site at Marsden Point. From that study it was not clear whether the patterns of bird use were typical of the site. The northland Port Corporation and the Department of Conservation were both interested in extending that study to allow ecological interpretations about the area to be made. This report outlines that study which has run from November 1996 until October 1997. The intertidal area from Blacksmiths Creek to the Refinery wharf is the area that was studied. The area was divided into grids during the 1994 study. Those same grids were used in the 1997 study. 16 Low tide counts were made during the study. In each count the species, number and utilisation of the intertidal flats by the birds was recorded. The data collected was then analysed and is included in this report. Particular note was made of New Zealand Dotterel and Variable Oystercatcher numbers as they are classified as threatened species. A mean of 2.9 NZ Dotterel and 2.0 Oystercatcher were found during the low tide counts. The number of each species found in the 1994 study has been compared to the number of birds found in 1997. The comparison shows that similar numbers of birds were found in each study. This is important as it validates both studies. The areas adjacent to the study area have been studied for comparison purposes. Three counts were made in these adjacent areas at the same time as counts were made in the study area. The information collected shows that birds are using the study area as part of a larger feeding pattern over the low tide cycle. The density of birds at each location has been calculated so that different areas can be compared. Whenever these comparisons are made it is important to realise that the three counts may only show a snapshot of the overall feeding patterns. There is a high tide roost adjacent to Blacksmiths Creek. The number of birds found at high tide on the roost was recorded on 5 occasions to provide information about the high tide roost. Between 280 and 400 and a mean of 350 South Island Pied Oystercatcher were found on the roost on those counts.other birds utilising the roost included Bar Tailed Godwit (mean number 115), Pied Stilt (mean number 19) , Variable Oystercatcher (mean number 4), Knot (mean number 8), and Black Backed Gulls (mean number of 33). A comparison was made between three years total Whangarei Harbour high tide shorebird populations and three March high tide counts at Blacksmiths Creek roost. The comparison showed that between 17 and 37% of the South Island Pied Oystercatcher, 4 and 17 % of Variable Oystercatcher and 2 and 5 % of Bar Tailed Godwit in Whangarei Harbour were using the Blacksmiths Creek high tide roost. To ascertain the utilisation of shorebirds of the intertidal flats at night . 3 night time counts were made. At the time that these counts were made the birds were not feeding in the study area at night. The aim of the study was to provide accurate information for an assessment of the ecological effects of the proposed port on the shorebirds found in the study area. That assessment can now be made.
Table of Contents: Topic Introduction Method Grid locations and Descriptions Adjacent area count locations Results: Low tide results Low tide data analysis Comparison between shorebird numbers in 1994 and 1997 Low tide comparison study area and Whangarei Harbour NZ Dotterel Variable Oyster Catcher Adjacent area count analysis High tide result summary High tide data analysis night time results Conclusion References Acknowledgments
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