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Abstract
As the general public and scientists alike become more aware of the suggested patterns and problems of global climate change, many begin to realize that not just humans will be affected in the future. We are but one of many species that will be forced to adapt to changing conditions. Those who are unable or fail to adapt will be eliminated by others who can. It is important to understand that regional changes are much more accurate and useful to examine rather than global trends. Also, when global trends are measurable the changes have already affected the regional elements in huge ways; there exists no reaction time. It is also impossible to apply these regional changes to all species within its limits. Consequently, we have chosen birds to narrow our study on how climate change affects species distribution. Birds are excellent indicators of change in spatial distribution. We will first examine the different problems and issues surrounding global climate change. Then we will discuss the different theories seen behind the alteration of species distribution due to climate change, and why this is important. We will then look at how different species distributions have altered in general. To focus we will concentrate on the change in distribution of birds (as they are a good example of species indicators) including factors as abundance and location, testing if they have changed within the recent past and whether or not these results can be attributed to climate changes.
Introduction
In recent history the world climate has seen significant changes. These changes are not necessarily uncommon, but as far as we can tell the rate and nature of the changes appear to be abnormal. Global climate change includes the theory of global warming or a rise of temperature due to the increase of greenhouse gases. Scientists have suggested that the earthÕs average temperature has increased by as much as 0.6¡C (Walther et al., 2002). The estimates on this figure vary and it is projected to rise another 1-3.5¡C in the next century (Hughes, 2000). While this might not seem like much, the effects of a small temperature increase can be impressive. The theory behind global warming suggests that increased human activity is putting an abnormally high amount of greenhouse gases (carbon dioxide, methane, and nitrous oxide) in to the atmosphere. This greenhouse blanket that warms and allows the earth to sustain life is growing ever thicker. This increase of human input is causing the blanket to grow too thick and keep in too much heat. (NZCCO) This process is known as global warming and leads to potential climate changes. These changes in climate alter many other aspects of the natural environment; everything from alterations in ice sheets and glaciers to trended movements of biomes and species distribution.
Global warming is a complicated process with many causes and effects that are difficult to predict or control. At the current time it is the general consensus of the scientific community that global warming and the increase in temperature is largely due to human action and influence. There exist two types of green house effects; the natural greenhouse effect and the enhanced greenhouse effect. The natural greenhouse effect prevents the earth from being frigid and inhospitable. ItÕs because of these gases that life on this planet exist, ÒThe natural greenhouse effect causes the mean temperature of the earthÕs surface to be about 33 degrees C warmer than it would be if natural greenhouse gases were not present.Ó (NASA 2) The enhanced greenhouse effect is the unnatural effect that was brought on by humans, ÒItÕs the possible raising of the mean temperature of the EarthÕs surface above that occurring due to the natural greenhouse effect.Ó (2) The greenhouse gases that are the culprits in the enhanced greenhouse effect are mainly water vapor, ozone, carbon dioxide, methane, nitrous oxide, and chlorofluorocarbons (CFCÕs). Carbon dioxide along with the other gases have been increasing in the atmosphere over the past couple centuries, ÒThere ahs been about a 25 increase in carbon dioxide in the atmosphere from 270 or 280 ppm 250 years ago, to approximately 360 ppm today.Ó (3) These records and recordings of the abundance of carbon fluctuate depending on the hemisphere youÕre in, the season it is, and at what time of day it is. Interestingly enough the two most abundant gases in the atmosphere, nitrogen and oxygen, have no effect on the greenhouse warming. As greenhouse warming continues there do exist processes that seem to counter the downward spiral of global warming. One example of these processes is in relation to the carbon cycle. It has been noted that in the global plant community many plants seem to be taking up more carbon dioxide and storing it in either biomass or soil. It is doing this in association with the increased carbon dioxide that is present in the atmosphere. This occurs for different reasons, Òair temperatures over the land have increased, resulting in a lengthened growing season in the northern and mid-latitudesÉa gradual and slight warming seems to have favored photosynthesis over respiration-decomposition with far-reaching effects on the global carbon balance.Ó (NASA FACTS 2) As seen global warming is a serious happening potentially affecting sea levels, glaciation, agriculture, ocean cycle, human health, species spatial distribution, and much more.
Scientists have begun to study how the changes in climate are affecting a wide range of species. There have been a wide variety of groups including plants and animals, vertebrates and invertebrates, terrestrial and aquatic, and tropical and polar species that have been monitored. They have looked at everything from physiology, phenology, distribution, adaptation, community, and ecosystem structure. Climate plays an important role when it comes to the distribution of organisms. Significant shifts in distribution have been seen before as climate shifts have occurred. Many organisms are able to shift with the changing climate and adapt to the modification, others cannot. Many of those who cannot are done in by three main causes; when warming exceeds the migrational capabilities of a species, when there are losses of habitat during progressive shifts of climatic conditions, and when there are reductions in species diversity through reductions in habitat patch size. (GWTBD 4) The basic theory behind the decline in patch area and associated species loss is associated with the theory of biogeography, Òwhich predicted that species diversity would decrease with island size.Ó (5) This theory is thought to hold true in reference to a patch of forest, or ocean. When discussing the dilemma of when warming exceeds migrational capabilities of species there is much that we cannot understand or calculate. No one, at this point, is entirely sure at what rate species will be able to migrate under such stresses. This makes it difficult to predict a likely out come if these events were to come about. Instead of predicting how fast organisms will move, we can predict how fast organisms will have to move in order to keep up. Because of already established models that predict current and future distributions of major vegetation types we can predict how fast biomes would move. If this were accomplished we could also get a general understanding of how fast the species found within each of the biomes would also have to move. The species in the biomes would most likely have to remain in their biomes to survive. The third event that species may have to deal with is the losses of habitats during progressive shifts of climatic conditions. With this issue one of the main elements that would restrict species movement and a loss of habitat is human induced. When biomes shift they could potentially shift into areas that are fragmented by human build and construction. Fragmentation of these areas could potentially result in species loss. (GWTBD)
Specific examples of a variety of organisms are useful in observing trends of climate change on species distributions. It is often expected that organisms will move poleward to compensate for the warming. This has been observed in tree species in the eastern U.S. (Iverson & Prasad, 2002). With regard to species distribution in plants, it has been found that some species are unable to establish populations in new areas when faced with climate change and habitat fragmentation (Primack & Miao, 1992). Lichens have also been monitored and it seems that species that ordinarily have a subtropical distribution are invading more poleward areas (van Herk et al. 2002). The effects on animals can be studied more specifically in terrestrial or aquatic settings. Or, the intertidal zone is also a great region to study. It has been proposed that the animals in this region will be most affected by the effects of global warming. Stillman has studied the effects of temperature changes in crabs in the intertidal zone (2002). Changes in insect distributions can lead to other human implications through the spread of diseases. For example, mosquitoes have been reported at higher altitudes in Latin America and Africa, areas which already have high instances of malaria (Hughes, 2000). Lastly, corals are a very important example to look at for the effects of climate change. They are already extremely sensitive organisms who are affected by even slight natural changes in salinity or temperature. There have been many studies done to see the effects of global warming on corals and the evidence suggests mass extinctions of certain species (Hughes, 2000).
We have narrowed down our study from these categories and have chosen to primarily look at the effects of climate change on different species of birds. Birds are excellent indicators of climate change because effects can be seen quickly due to their mobile lifestyles as compared to more sedentary groups of species. Some studies have found that bird distributions are most affected by climate and altitude (Storch et al, 2003). The climate factors have been studied by many and have found that not only do bird distributions vary based on temperature but also largely on precipitation as well (Githaiga-Mwicigi, 2002). Birds have been subjected to changes due to habitat degradation along with these indirect effects from humans such as climate change and other disturbances. When these factors are coupled with limitations based on specialization, certain species are more influenced than others (Julliard et al 2003). In other cases, some species of birds have been affected by the human suppression of natural disturbances. For example, bird ecosystems are often regulated by events such as fires or droughts. As humans subdue these natural disturbances, the ecosystems are bound to be impacted (Brawn, et al. 2001). These natural disturbances can characterize vegetation in biomes and thus land-use is also studied in relation to bird species distribution as it directly impacts vegetation. Venier et al. found that indeed land-use patterns do influence the distribution of certain species of birds (2004). Their migratory patterns can be tracked and their nests serve as important studies on their hatching patterns. Their phenology, or timing of life cycle events such as hatching, can indicate how climate change is affecting them. As the number of cold days change, for example, their phonological events might also change due to this. It has been suspected that breeding ranges would move upward in latitude or elevation due to the increase in temperatures. However, from some of the studies so far, this theory has not yet been supported (Archaux, 2004). Bird experiments have been well documented worldwide and thus we feel that they are an excellent group to study in order to see how climate change can directly affect certain speciesÕ distributions. We will look to answer the question of whether or not birds are a good indicator of climate change impacts and whether or not these studies can attribute the observed trends primarily to these causes as opposed to other compounding factors.
We plan to compile research that has been done regarding the species distributions of birds and how this relates to climate change. To begin, we will first study the known patterns of bird distribution globally and how the patterns fit with the biomes of different climatic regimes. Next, we will find studies of how these Ònormal or pre-climate changeÓ patterns have changed. Specifically, we will look for regional variations between species. We will also look to examine what overall patterns can be seen with the changes in distributions. From what we have learned so far with our preliminary research, we predict that we will see many species whose distributions have shifted poleward in response to increase in temperatures. Additionally, we predict that most species will be experiencing early starts in life cycle activities such as hatching. This also can be attributed to the increase in temperature signaling the onset of spring to the birds. We expect that birds originally found in middle to high latitudes will have more visible effects because it seems that these latitudes are experiencing more of the increase in temperature. We expect to find that certain species of birds that are sensitive in their climatic conditions will be more negatively affected by climate change because of their inability to handle diverse conditions. We hope to accomplish a thorough compilation and analysis of studies of different species of birds.
Relevance
Due to the interest of many others in this and other related topics, there is a plethora of information regarding other studies similar to ours. Many have concentrated on a specific region of the world or a particular species. We will look at these and see if patterns emerge between or within species and between or within different regions. There is also an abundance of studies done regarding the spatial distribution of species in relation to specific habitats within a regional setting.
References:
Archaux, Frederic. ÒBreeding Upwards when Climate is Becoming Warmer: No Bird
Response in the French Alps.Ó Ibis. (2004). 146: 138-144.
This study included two sites in the French Alps: one in the north and one in the south. They recorded a 2.3Á C increase in temperature in the last 30 years, yet they did not find substantial results supporting the idea that climate change would alter the altitudinal distribution of bird species here.
Beard, Karen, Nicholas Hengartner, and David Skelly. ÒEffectiveness of Predicting
Breeding Bird Distribution Using Probabilistic Models.Ó Conservation Biology.
October (1999) 13: 5. 1108-1116.
This study looked at 40 species of birds in Idaho to see if models could be made including the factors of vegetation, climate, and spatial organization to predict the distribution of these species. From their model, they could accurately predict only 60% of the speciesÕ distributions and the null model accounted for 35% of the species distributions. Therefore while 60% is a fairly high percentage, this is not that high when compared to the null. Consequently, there needs to be much improvement on this model.
Brawn, Jeffrey, Scott Robinson, and Frank Thompson III. ÒThe Role of Disturbance in
Ecology and Conservation of Birds.Ó Annual Reviews of Ecological Systems. (001)
32: 251-276.
This article explores natural disturbances and their role in the populations of certain bird species. With the suppression of these disturbances and the addition of human disturbances such as agriculture and development, they have recorded declining abundances of species.
Couvet, Denis, Frederic Jiguet, and Romain Julliard. ÒCommon Birds Facing Global
Changes: What Makes a Species at Risk?Ó Global Change Biology (2003) 10,
148-154.
This article looked specifically at how the distribution of birds will be affected by global climate change and overall human disturbance. This study was conducted in Europe. They then compared these results with the patterns of butterflies.
French, D.D. and N. Picozzi. ÔFunctional GroupsÕ of Bird Species, Biodiversity, and
Landscapes in Scotland.Ó Journal of Biogeography (2002) 29:231-259.
This article grouped almost all the bird species found in Scotland. They further studied season and spatial scales to address biodiversity in relation to land use patterns. They found that they were associated with strata.
Githaiga-Mwicigi, Jean, Dean Fairbanks, and Guy Midgley. ÒHierarchical Processes
Define Spatial Pattern of Avian Assemblages Restricted and Endemic to the Arid
Karoo, South Africa.Ó Journal of Biogeography. (2002). 29:1067-1087.
This study looked at biotic and abiotic factors with regional gradients to view distributions of bird communities. They used grid cells and GIS in their methods. They could account for 85% of the variation of their models.
Gomez de Silva, Hector and Rodrigo Medellin. ÒAre Land Bird Assemblages
Functionally Saturated? An Empirical Test in MexicoÓ OIKOS (2002). 96: 169-181.
This article looked at food resources and climate as related to bird distribution in Mexico. They predicted that excess resources would be found only in extreme climates. They found that only 2 assemblages of the 77 studied had excess resources and these were the two with the lowest temperature and lowest precipitation.
MacDonald, Michael and J.B. Kirkpatrick. ÒExplaining Bird Species Composition and
Richness in Eucalypt-dominated Remnants in Sub-humid Tasmania.Ó Journal of
Biogeography (2003). 30: 1415-1426.
This study looked at the distribution of birds in fragmented agricultural landscapes in Australia. They were examining all the following factors: species, composition, richness, abundance, and diversity and their relationship with environmental variables.
Storch, David et al. ÒDistribution Patterns in Butterflies and Birds of the Czech Republic:
Separating Effects of Habitat and Geographical Position.Ó Journal of Biogeography (2003). 30: 1195-1205.
This study looked at environmental factors and geographical positions in different species. Their design included a series of gird cells in distribution atlases. They found that altitude and climate accounted for the most variance within their studies and that birds were also affected by the area of water bodies for obvious reasons.
Thuiller, Wilfried, Miguel Araujo, and Sandra Lavorel. ÒDo we need Land-cover data to
Model Species Distribution in Europe?Ó Journal of Biogeography (2004). 31: 353-361
This article looked at the influence of land-cover and climate on the distribution of 440 bird species and other organisms across Europe. They used bioclimatic models, regression of land cover and mixed models for their methods. They found that land-cover is driven primarily by climate.
Venier, L.A. et al. ÒClimate and Satellite-derived Land Cover for Predicting Breeding
Bird Distribution in the Great Lakes Basin.Ó Journal of Biogeography. (2004). 31:
315-331.
This article looked at climate and land cover to predict the distribution of 10 forest songbird species in the Great Lakes region. Overall, they found that these factors do predict the distribution of these 10 species.
http://www.climatechange.govt.nz/resources/info-sheets/more-than-global-warming.pdf (NZCCO) This website explains a real general overview or global warming and climate change meant for the real general part of our proposal.
http://www.gsfc.nasa.gov/gsfc/service/gallery/fact_sheets/earthsci/eos/global_warming.pdf (NASA) More general overviews about global warming for the beginning of our proposal
http://www.gcrio.org/OnLnDoc/pdf/global_warming030101.pdf general overview of global warming and change in species distribution. Nothing specific about a specific speciesÉ.just general overview for beginning of proposal
http://www.worldwildlife.org/climate/biodiversity_decline.pdf (GWTBD) modeling changes in species and biome movementÉgeneral..good article
http://earthobservatory.nasa.gov/Newsroom/MediaResources/Changing_Global_Land.pdf (NASA FACTS) Great site on biome movements, lots of general information about plant and general biomes, and has a good deal of excellent graphs.
http://www.nrel.colostate.edu/brd_global_change/proj_15_mig_birds.html
This website explains the finer points explaining the change in spatial distribution of several bird populations. They use four different species of bird as examples. Four different species that exist in four different areas.
http://www.gisdevelopment.net/aars/acrs/2000/ts7/gdi001.shtml
This website is a test that describes how GIS explains and quantifies Habitat Suitability Index for a bird populations given habitat area.
http://www.cnr.colostate.edu/~denis/thesis_and_dissertation/haire.html
This website discusses the relationship between bird abundance and landscape. Landscapes were described through GIS monitoring, and bird variance in spatial distribution was gathered through a separate ongoing study.
http://www.nrel.colostate.edu/brd_global_change/proj_55_prairie_birds.html
This website describes a general overview of bird distribution in the grassland region of the United States.
http://www.sdsc.edu/~ESA/bulletinimpacts.htm
This website discusses different species distributions in association with different possibly effected elements of global climate change; temp, precip, water temp, water availability.
Materials/ Methods
We will use many maps including physical geographical maps of existing biomes and species distributions as patterns have been observed (these maps are contained within many of the sources seen above). We will also attempt to make our own maps of how the distributions of respective species have changed and these patterns that have been observed. We will use different studies in our analysis to graph different species vs. tests of sensitivity, latitudinal change, or phenological changes. With these variables we can test to see if these correlations are significant indicating important results as related to climate change. We will be testing distribution data sets against these many different aspects to see if there are specific overwhelming factors that influence a change in the distribution possible leading to the conclusion that these changes are not related to climate change, but another factor.
TIMELINE:
3/8-3/12 Ð Reread sources and start organizing valuable information and usable maps and statistical analyses. Also find and look through data sets.
3/20-3/27- Continue looking through data sets and finalize which data sets will be used and exactly which data sets will be compared.
3/28-3/31 Ð create graphs from data sets
4/1-4/15 Ð analyze data sets and graphs. Make comparisons between graphs and draw conclusions from graphs as to which data is significant and in what relation does each have to the prospect of being effected by global climate change
4/16-forward Ð draw further conclusions and solidify write-up.
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