Abstract
This research studied the abundance and distribution of seabirds on the sea around the Phillip Island from ten past twelve to thirty minutes past nine o’clock. The birds were tallied in a single line transect from the port and back. The birds identified during this study were sea gull, kelp gull, cape netrel, pacific gull, and silver gull among other birds. The researcher found that the distribution of birds was not uniform where bird of two species had dominated the area as seen in 1:40 PM. Throughout the line transect set along the shores through the navigating conducted using a boat, the researcher aimed at developing a tactical hypothesis that birds had no uniformity through an area. It was argued that the distribution was centre in accordance to the availability of resources such a food and shelter. The abundance was, therefore, coherent to the sites where these resources were unlimited or adequately supplied over time. The findings of the researcher were coherent to this supposition.
Introduction
Essentially, the study of birds, their movements and behaviours are not only prudent to prevailing society of Fauna, but also fundamental in the distribution of plant species across the oceans into remote islands. This attribute shows that there are fundamental concerns that involve the development of natural resources and attenuation of a sustainable developmental zone with adequate resources to facilitate the ego of natural existence. Whereas these aspects are no doubt precarious within the current exploitative nature, their studies do not cease due to the interest of researchers of the avian species. Birds are the most cosmopolitan animals across the globe which harbours the globe in entirety. They do not only flock together to productive regions across the globe, but also keep memory of the resources and benefits they received from such places. This academic investigation emulates these researchers in their endeavours to provide reliable information regarding their practices and behaviours. The research was aimed to introduce the concepts of fundamental research techniques for the future research expected from the evaluation. Whereas this fundamental or core ideology is between taught, there are lessons learnt about the existence of the seabird species, their identification through dichotomy, and evaluation of their abundance and distribution.
The factors that influence the distribution and abundance of the seabirds at the sea is of important especially when studying their movement and foraging areas in their eco-system. To understand their role in energy fluxes and nutrients of the sea birds it is important to consider their Food chain. Limited information on the distribution of the seabird off the coastline of Phillip Island is found. Species record lists of seabirds obtain form different location during the survey has been provided. Distribution and abundance of the species at the seal rock has been surveyed. However, investigation of variation in the number of seabird species at an interval of 5 minutes was recorded. Distribution in both left and right side was noted to ensure that data collected was more of accurate.
Sites such as estuaries, inlet and bays can be important nursery areas for fish species. These water bodies influence the movement of the fish species to, and within, have been shown to affect the distribution diversity and and abundance of the seabirds. Fluctuation in the number of seabirds dominating in such water bodies have been shown to associate with the invasion of other species to the breeding colonies. Along the Phillip coastline, Cowes, Bass Strait and Western Port Bay are considered to be the nursery and spawning zone (Dann 2003).
Some studies have documented the association of seasonal influxes in Post-larval fish population, breeding periods, fluctuation in sea-surface temperature as well as variation in the distribution diversity and abundance of seabirds. Diversification, distribution and factors influencing seasonal abundance of other species in the region is not well studied. Also, peaks in Little Penguine numbers in Western Port have been shown to concur with the influxes into the area of juvenile pilchard and anchovies.
The distribution, biomass and abundance of different species of seabirds in were surveyed in different locations of Phillip Island. The surveyed conducted started from Cowes and goes through the southern reaches of Western Port Bay, into Bass Strait and back to the Cowes (Norman 1992b). Individual’s counts of the seabirds were recorded along 500 meters from the boat using the binoculars and bird identification guides provided. This was done at approximately 5 min intervals. There was a record of nine seabirds entered using the right-angled sector of the bow which incorporated 5 visiting species and 4 native species according to an earlier researcher from the Western Port Bay and Cowes in this order. The species that reappeared more often included the Puffinus tenuirostris (Short-tailed Shearwater), seconded by Larus novahollandiae (Silver Gull), Sterna bergii (Crested Tern) and lastly P. fuscescens (Black faced Cormorant) as other researcher had found (Dann et al. 2003). Distribution of seabirds along the all areas of survey was not uniform.
In Cowes, the pursuit divers such as Kelp Gull and cormorant species were abundant as per the data recorded. On the contrary, the surface-seizing and plunging species predominate in the Bass Strait. Other species involving shallow-plunging and pursuit-plunging prevail in several parts of Western Port Bay (Sterry & Lings 1995). The report of a survey conducted between 1991 and 1993 indicates that abundance of the species differs seasonally with the highest number record in late summer-early autumn. Average biomass obtained was taken from the seabird species that was recorded as the highest number in different locations. The biomass density from the analysis was similar to those found in the Western Port Bay report conducted between 1991 and 1994. The aim of this study is to describe the species composition of seabirds in Philip Island and assess their distribution and abundance.
Methods
The researchers sought to start the data collection from Cowes and circumnavigate the island using the single line transects. The collection zone commences from Cowes to the Western Port Bay and back around the island. The seabirds were recorded at intervals of five minutes where the location was indicated together with time. The birds that were recorded were identified depending on the commonest species and the guide carried to identify them. Apart from the boat for facilitating the movement across transect in the sea, binoculars were used to cover the recommended study zone of 500 m. Moreover, the location, time, and directions were recorded in a table to facilitate coherent view of data. The GPS locations were identified through the use of phones and other trackers which also showed the directions of movement. The researchers also made various stops in a bid to achieve various outcomes as per the standards of findings required by the instructor. These stops were also set to facilitate the collection of data at the most strategic places where good views of the seabirds’ population can be performed effectively. These factors will avail adequate, reliable, and relevant data for the analysis which will prompt the release of randomized collection through the single transect procedures.
Phillip Island lies in the southern entrance where a large Island occupies the centre of the bay. Between 1991 and 1994, several surveys undertaken were completed in more than 3 years. The time schedule to complete the survey was extended due to unfavourable weather as well engine failure. Four counts had to be abandoned which result in an attempt to space the counts at four-weekly intervals. Seabirds were counted along 81-km series of transects from the running at the speed 20-25 knots per hour.
Transients used were perpendicular to the main channels in order to cover the entire range of sub-tidal water depths in each section of the Philips Island. Intertidal areas were not transverse and with the exception of those areas in the Bass Strait and Cowes. Areas with sub tidal less than 2m deep at the high tide were ignored.
To facilitate easy study of the seabirds, observation was done on either side of 8-m boat (eye elevation of approximately 3 m) and birds counted consistently in the right-angled sector from the bow to either starboard or port. Observers recorded each bird seen up to 500 metres from the boat onto tape cassette. Binoculars were used to make observation easier and facilitate faster grouping of birds in to their taxa. Each bird was identified with the help of bird identification guide provided to the species or commonest taxon where possible. When counting, accuracy was impaired the present of large number of birds as well as the variable sea conditions. No record was made between 12.35 to 12.40 due to poor visibility and rain. The boat had to be stop to allow for observers to make accurate counting. To avoid misleading data, counting was done on a day when the wind speed and inclement weather was favourable. The count usually takes an interval of 5 minutes and was carried out around the middle of the day (12.10) and, when possible, within few hours of high tide on the back journey. Identifications were made using binoculars and bird identification guide.
Average Biomass across sexes was taken from Higgins and Davies (1995) and Marchant and Higgins (1990) to calculate the body mass of individual species observed throughout the survey practical. Data are presented as by means.
Results
Species diversity and distribution
In total, 9 different species of seabird taxa were recorded during the study on practical session. An additional of nine species of water birds and waders were observed during the survey but was not included during calculation of the biomass of individual species (Schneider 1990). Such species includes Cynus atratus, Black Swan, Oyster Catcher spp., Haematopus spp., Masked Lapwing, Venellus miles; Whited-faced Heron, Aedea novaehollondies, Egret spp., Spoonbill spp., Egretta spp., Platalae spp.; Curlew Sandpiper, Sacred Ibis, Calidris ferruginea; Threskiornis aethiopica; Straw-necked Ibis, T. spinicollis and Heron (Kokko, Harris, & Wanless 2004). These species was recorded and taken as additional information but excluded from further analyses. Of the 9 taxa analysed, 4 are known to have local breeding colonies within 40 km of the coastal line, another three breed within Western Port and Bass strait and two are considered a long-distance migrants. The distribution of the seabirds starting from Cowes, through Western Port Bay and Bass Strait was not uniform
The greatest number of Silver Gull, Australasian Gannet and shearwater individuals was observed and recorded in Western port. In Bass Strait, Silver Gulls, Crested Terns, Kelp Gull and Black-faced Cormorants were numerous as compared to other regions.
Abundance, seasonal variation and biomass
Though observation was taken at the interval of 5 minutes, at 1.40 pm, (48 %and 32 % of the survey, respectively), Short-tailed Shearwater and fluttering shearwaters were by far the most numerous species recorded, numbering in their thousand present. Their present in the Western Port was uncountable from 1.40 to 1.45 as per the practical record. Compared to other study, these species in Western Port was highly seasonal, occurring mostly in the years between 1992 and 1993. It occurs mostly in January-march where their number recorded was high.
Silver Gulls, Created Terns, and Pacific Gull were the most numerous species recorded, with peak number of individuals as per the record. Also, from other published records, it shows that the highest number was recorded in late summer-autumn and lowest in winter- spring, with the exception of the peak for all species occurring in the month of October 1992 (Marchant & Higgins 1990). Other species were recorded in less number with the exception of one record of Silver Gull. The presence of the Australasian Gannet and Pacific Gulls at an interval of 5 minutes occur with highest numbers at 1.15 and 1.00 respectively. From other published sources, these birds’ species was highly seasonal, with peak numbers generally occurring in February-May. Similarly, Black-faces Cormorant and Crested Tern were recorded in peak numbers at 12.50. On the other hand, the Australasian Pelican and cormorant species number fluctuates from time to time due to weather changes.
The highest observed biomass occurred between 1.40 and 2.15 which was heavily influenced by the present of Short-tailed Shearwaters Birds. From 12.10 to 3.30 Silver Gull contributed the greatest proportion of the observed biomass. Their lowest contribution to biomass was at 1.40 to 2.25 as per the result obtained from calculations. This aspect was due to the arrival of other species with similar food chain. Despite there being fewer than 6 recorded at a time, Cormorants contributed a much high percentage of biomass at the overcast and breezy weather
Similarly, the few Australasian Pelicans and Crested Tern recorded at an interval of 5 minutes accounted for an average mass of the observed biomass at 1.50 t0 3.15.
Table1. Summary of seabirds’ species observed within Phillips Island recorded at an interval of 5 minutes and the total number of individuals recorded during counts.
Discussion
The number of different taxa record in the present study entails some similarity to that reported by Norman in port Phillip Bay and off the southern coast of Philip Island. Nevertheless, twelve and fourteen of the taxa observed in the study was common to the bay of Port Phillips and the sea shores on the southern side of Phillip Island in this respect.
Species such as cormorant (including of the Black-faces Cormorant) and silver gulls were recorded mostly in all weather in all the ports. These species were recorded in relatively low numbers and their occurrences show no much difference at the time interval. At around 12:40, seabirds arrive at the seal rock. Species such as relp gull, crested tern, silver gull were found in large number as compared to other species. Crested Terns and Silver Gulls between the time of arrival and departure were found on both left and right side. At 12:45, Crested Tern was found on the right side while at 1.05 it was seen at the left side.
Few studies note that the peak of Silver Gull and Little Penguins in the end of summer to the beginning of autumn match with the arrival of young clupeoid fishes species within the Western Port (Higgins & Davies 1995). CRESTED Tern in this Island feed on small Australia Anchovy and Jack Mackerel and are often recorded in high number during the late summer to early autumn. The occurrence of the large numbers of Short-tailed Shearwater in Phillip Island reflects the close proximity to the large breeding colonies which is not the case in the practical study. The present of this species in the study was evaluated at time intervals which could not relate to the study carried out in the Western Port during January-March 1992 and 1993.
The concurrent large number of Short-tailed Shearwater at 1.40 may indicate that they relied on juvenile fish moving in the area. Dolphins were also spotted on the region showing the present of a food chain in the ecosystem. Also, Silver Gulls were found almost in all time intervals which indicate that they obtain a significant proportion of their diet from terrestrial scavenging. From the record, at 2.30 Silver Gulls are seen at the left side.
References
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