How Climate Change Changes the Distribution of Common Blackbird over Time

Cygnus (2013) 1:1-6

DOI [21291197] 

RESEARCH ARTICLE__________________________________                                                               

How Climate Change Changes The Distribution of Common Blackbird Over Time

Chloe  Cheng

Received: [Submission date] / Accepted: [Date revisions due]* Editors to complete – authors please do not delete this line

Abstract   
Climate change, mainly global warming, has been a great issue during the recent years as more and more evidence indicates how it greatly impacts the whole ecosystem including wide range of population regardless of marine or land species. However, the effects of climate change to certain species in Australia still remain a question mark to the scientists and therefore further investigation is required to examine if it contributes to a negative effect on the species which put them in a risk of extinction. This article explores the implications of the change in global temperature over time to the distribution of Common Blackbird in Australia through mapping analysis and obtaning climate data sets to make comparison. Through the findings, future predictions on distribution of the species can be made according to the trend of global warming.

My research is mainly based on researching the relationship between the climate change and the distribution of  Common Blackbird. It is believed that the Common Blackbird will distribute to the area with slightly cooler climates and with higher level of rainfall.

Keywords – climate change, common blackbird, distribution, rainfall, species,change

 Introduction

The Common Blackbird (Turdus Merula) is also named Eurasian Blackbird (especially in North America) so it will not get confused by other local black bird species that shares the similar look. Male, female and juvenile birds are distinguished by their different displayed characteristics (mainly the feather colour— males are black, while females and juveniles appear to be dark brown in colour). T.Merula partially migrate, fully migrate or even resident depending on the latitude (Clement et al.  2000). They are omnivores which feed on whole range of seeds and fruit as well as insects like spiders and earthworms. (Morcombe, M. 2000).
In this study, I explore how climate change effects the distribution of T.Merula over time in Australia by reviewing the data sets of occurrence records obtained from Atlas of Living Australia dated back to year 1848 as well as Climate Watch for the recent year. Climate data sets are also extracted from Australia Government Bureau of Meteorology to see how the species responds to the change in climate, mainly temperature and rainfall (which the global warming contribute the most changes). Recently, climate researchers use climate-modelling software to produce a result that shows the area of Australia where climate is considered suitable for T.Merula (Birdata. 2007 Atlas Distribution Map—Common Blackbird). Based purely on an assessment of climate parameters, they are more likely to survive in cooler upland parts of Australia (South East).

Recent studies indicate that global warming has caused the gradual rise in Australia’s temperature and a significant decrease in the level of rainfall, especially at South East area. It leads to the expansion in distribution as well as having a trend where the birds starting to shift to up North. Therefore I hypothesised that the climate change in Australia results in the extension of range to the area that has ideal climate as the mapping analysis demonstrates the increase in sightings in areas where the climate is a bit cooler and with more abundant rainfall.

 Materials and Methods

The main aspect for this research is to determine the change in the distribution of Common Blackbird (Turdus Merula), therefore a wide spanning data set of over 40,000 sighting records (from 1893 till present,2013) obtained from Atlas of Living Australia. Atlas of Living Australia provides detailed data sets and analysis of different species across Australia, which have been examine and recorded since 1800s.


My research mostly focus on the specific locations as well as the specific timing where T.Merula appeared, so I only extract the data that displays the longitude, latitude and the date of occurrence (there are certain data that do not have their longitude and latitude shown). My data is manipulated using Microsoft Excel to make a spread sheet with the irrelevant details excluded, leaving only the longitude, latitude and occurrence year. I sort my data into six different groups of time interval, which is 20 years each except from 1995 till 2013. Each group of data is imported to Atlas Living of Australia for mapping analysis to produce a map for each group that shows the distribution of T.Merula  in Australia (the map is not restricted to Australia in case any outliers appear in the data). Six maps are then produced and are studied individually to inspect the change in distribution over time.


In order to investigate the effects of climate change to the distribution of T.Merula over time, it is essential to have data that gives the change in mean temperature and average rainfall in Australia over years. Therefore I have obtained climate data from Australia Government Bureau of Meteorology to determine the past changes of Australia climate and compare to the change in distribution of T.Merula over time. Besides that, it provides some description on the change of climate in Australia which is very helpful for my study.
Only certain data sets from Climate Watch are used because most of them focus on the behaviours rather than the location, so not all of the data has the latitude and longitude shown (which is the most essential thing for this research). Therefore I chose only data sets for 2013 as the specific locations of occurrence are included. The data sets from Climate Watch are then mixed with those from Atlas Living of Australia and imported together for mapping analysis.

 Results

The climate data reveals a strong evidence on how global warming has resulting a significant change in Australia’s climate. Figure 1 shows a distinct trend of rising in the annual mean temperature in Australia mainland. Over the last century, Australia has experienced an average warming trend of around 0.9 °C; globally 13 of the 14 warmest years on record occurred between 1995 and 2008. (Bureau of Meteorology, Annual Australia Climate Statement 2008).

[pic 1]

Figure 1. Annual mean temperature anomalies for Australia. The World Meteorological Organisation has indicated that 2008 has been the world’s tenth warmest year on record.