4. METHODS 4.1 Timing 4.2 Weather Conditions 4.3 Terrestrial Bird Surveys
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Tugun Bypass: Boyd Street to Stewart Road – Impacts on Birds 4. METHODS 4.1 Timing Surveys were conducted during two time periods to obtain a good understanding of the bird species that may utilise the study area, and to document changes in habitat use between seasons. A spring survey was conducted over five days, from the 23rd of October to the 27th of October 2000. This time period coincided with a quarter moon phase. The lunar conditions experienced during the survey were adequate for sampling nocturnal birds. A summer survey was conducted over six days, and four nights. The survey was originally scheduled to commence on the 31st of January 2001, however persistent rain meant that the survey was postponed. Surveys were conducted between the 4th and 6th and 15th and 17th of February 2001. Surveys were conducted during the first and last quarter moon phases. 4.2 Weather conditions 4.2.1 Spring survey The spring survey was conducted during mainly fine weather. Although rain and storms occurred on each night of the survey the days were mostly fine with light winds and warm sunny conditions (Table 2a, Appendix 2). 4.2.2 Summer survey Weather conditions were variable during the summer survey. Initial surveys from the 4th to the 6th of February were conducted in fine conditions following a prolonged period of heavy rain. Surveys between the 15th and 17th of February were conducted during mixed weather conditions. Days were characterised by heavy cloud cover and light showers, whilst nights were mostly fine with calm conditions (Table 2b, Appendix 2). 4.3 Terrestrial bird surveys During both the spring and summer surveys a comprehensive assessment was conducted of all terrestrial habitats in the study area. Both surveys included targeted searches for legislatively protected species2, and general surveys for all bird species. A variety of methods were employed to survey the terrestrial bird community. The terrestrial bird survey included a combination of methods specified by the NSW National Parks and Wildlife Service (1999), and standard procedures that targeted specific groups of birds. Terrestrial surveys included a general quantitative and qualitative assessment of species richness and relative abundance, within the major habitat types, and targeted surveys for threatened species in selected habitats. Nomenclature used throughout the report follows Christidis and Boles (1994). 2 Legislatively protected species include any species listed on the state or commonwealth legislation or international agreements. Legislatively protected species are also referred to as threatened species. Sandpiper Ecological Surveys 7 Tugun Bypass: Boyd Street to Stewart Road – Impacts on Birds 4.3.1 Habitat assessment Prior to the commencement of bird surveys a baseline assessment of habitat types present within the study area was conducted. This assessment involved a brief perusal of the entire study area, with notes taken on each of the different habitat types. By identify the major habitat types present within the study area bird surveys could follow a stratified sampling design, and there was a greater likelihood that all habitat types would be adequately sampled. After the initial site inspection a more detailed assessment of habitat types was conducted. This assessment involved gathering a range of standard data on bird habitat within each of the delineated habitat types. Information on habitats and a map showing the location of each habitat type within the study area is provided in the results. 4.3.2 Point Counts To obtain some indication of the relative abundance of birds within different habitats in the study area replicate point counts were conducted in each habitat type. Point counts provide a rapid means of obtaining accurate data on the relative abundance of birds within specific habitats (Bibby et al. 1992). In the present case point counts were deemed to be superior to transects as the density of the vegetation in a number of habitats can greatly affect the ability to detect birds whilst moving along a transect. The use of point counts during the present study also provided data that were comparable to that collected during surveys along the southern part of the C4 alignment (Sandpiper Ecological Surveys 2001). Point count surveys consisted of three point counts along replicate 200 m transects. Each point was separated by 100 m. Five minutes was spent at each point recording the number of birds and species present within a 30 m radius of the observer. Birds were identified through direct observation and call. To reduce the impact of disturbance two minutes were spent waiting at each point prior to the commencement of each five-minute observation period (Bibby et al. 1992). Each point count site was regarded as a replicate. A total of 27 point count sites were sampled during the spring survey, with 18 sampled during the summer survey (Tables 3 & 4, Figure 2). Each point was surveyed on two non- consecutive mornings during each time period (i.e. spring and summer) by the same observer. The habitats sampled included, dry open forest, moist regrowth, swamp forest, and regrowth rainforest. Point counts were not conducted in disturbed land due to the limited extent of these habitats, and the difficulty associated with establishing replicate transects. Each transect was surveyed during favourable weather conditions. Point counts were conducted between 6.00 and 9.00 am (Daylight Savings Time). Although point count surveys focussed on birds within a 30 m radius of the observer all species outside of this area were recorded as being present. Bird species recorded during a slow traverse between point count locations (i.e. between 0 and 100 m along a transect) were also recorded to provide an indication of species richness. The data gathered during the slow traverse were analogous with the data gathered using the area search technique described below. 4.3.3 Area search Area searches were used to obtain information on the species richness of birds within each of the habitats in the study area. The data collected during each area search consisted only of the number of species present within a particular habitat. Area searches were conducted between 6.00am and 10.30 am, and involved a 30 to 60 minute meandering traverse by one observer. During a traverse the number of species present within each habitat was recorded by either sight or call. Sandpiper Ecological Surveys 8 1 2 LEGEND N Proposed highway Proposed railway Proposed bridge 2 Dawn playback 1 Dusk playback 5 Nocturnal playback Point counts General traverse spring General traverse summer Figure 2: Location of survey sites within the study area for the northern section of the proposed Tugun Bypass. Tugun Bypass: Boyd Street to Stewart Road – Impacts on Birds Repeated area searches were conducted in each of the major habitat types present in the study area (Figure 3). Repeat surveys were generally conducted in the same vicinity as the initial survey however, rarely did repeat surveys follow the same route (Figure 2). A total of 19 area searches were conducted within five habitats during spring, with 17 searches conducted in five habitats during summer (Tables 3 & 4). Almost 20 hours were spent conducting area searches during the summer and spring surveys. 4.3.4 General traverse General traverses were conducted in the late afternoon (i.e. between 3.00 and 7.30 pm), and consisted of walk transects through the study area. The objective of general traverses was to survey small habitats and to search for fauna features, such as evidence of foraging or roost sites. General traverses were conducted within four areas, north of existing highway, quarry, sewage treatment works and Woodgee Hill/Hidden Valley (Figure 2). Table 3: Summary of the survey effort expended during the spring survey of diurnal terrestrial birds for the proposed Tugun Bypass, Boyd Street to Stewart Road. * includes time taken during point counts; repeats = number of repeated surveys on each transect, traver = traverse. Habitat Point Count Area Search* General Traverse No. No Time No. No Time No. No Time points repeats (mins) traver repeats (mins) traver repeats (mins) Dry open forest 12 2 120 9 1 328 3 210 Regrowth rainforest 3 2 30 3 1 108 2 80 Moist regrowth 3 2 30 1 2 50 0 0 Swamp forest 6 2 60 4 1 118 0 0 Disturbed land 3 2 30 2 1 56 1 30 Woodland - - - - - - 1 30 Table 4: Summary of the survey effort expended during the summer survey of diurnal terrestrial birds for the proposed Tugun Bypass, Boyd Street to Stewart Road. * includes time taken during point count surveys. Abbreviations are the same as Table 1. Habitat Point Count Area Search* General Traverse No. No Time No. No Time No. No Time points repeats (mins) traver repeats (mins) traver repeats (mins) Dry open forest 6 2@3 45 6 1 185 3 1 175 Regrowth rainforest 3 2 30 4 1 175 2 1 165 Moist regrowth 3 2 30 2 2 60 1 1 20 Swamp forest 6 2 60 4 1 106 0 0 0 Disturbed land - - - 1 1 10 2 1 110 Woodland - - - - - - 1 60 Sandpiper Ecological Surveys 10 Tugun Bypass: Boyd Street to Stewart Road – Impacts on Birds 4.3.5 Playback Nocturnal playback Nocturnal playback was conducted during both the spring and summer surveys. The species targeted during the survey included masked owl (Tyto novaehollandiae), barking owl (Ninox connivens), powerful owl (Ninox strenua), grass owl (Tyto capensis), barn owl (Tyto alba), sooty owl (Tyto tenebricosa), and marbled frogmouth (Podargus ocellatus). During both spring and summer playback for masked, barking and powerful owls was conducted at three sites, whilst playback for grass owls was conducted at one additional site (Figure 2, Table 5).