Dynamics Of A Black Bear Population Within A Desert Metapopulation

Submitted By xflo1234x
Words: 1088
Pages: 5
Open Document
GG2043
Dynamics of a black bear population within a desert metapopulation
An abstract

11/30/2012

This articles aim was to describe the dynamics of an island population of black bears in a metapopulation, within Big Bend National Park between 1988-2002. Big Bend National Park is situated in the Chihuahuan Desert of western Texas, within the park there are islands of montane forest, in a matrix of desert grasslands and shrub lands. The article defines metapopulations ‘as a set of populations within some larger area, where typically migration from one local population to at least some other patches is possible’. It was this connection between different habitat islands that the article was investigating. The types of habitat which can sustain a black bear population occur above 1500m in the mountainous regions of the park, and consist of both woodland and chaparral. Between these mountain ranges there is a matrix of inhospitable habitat, which means that each island is effectively separated. However mitochondrial and genetic data suggest that there is a link between the different island populations, through male and female migration.
Big Bend National Park encompasses 320,000ha of the Chihuahuan Desert; the area is arid with low precipitation rates of 30.5cm/annum. Precipitation rates increase as elevation increases; this is one of the main reasons why the habitat can support a population of black bears. One of the methods that was employed was to use visitor observations, these records are kept on a database and have been monitored since 1901. The information which had been was considered e.g. location, time and characteristics of the bear(s). This information was then used to try and estimate the minimum number of females and cubs which were present in any given year. The other method which was used was field data. In order to obtain this data bears were trapped, and radiotransmitter collars attached to the trapped bears which weighed more than 40kg. These collars were fitted with a mortality switch and a breakaway mechanism. This data was then used to assess the trapping success, the composition of the population and the estimated population size; they estimated the population size using consensus data from 1999-2000. The density of males and females was then calculated by dividing the estimated minimum number of bears alive, by the areas which contained the home ranges for the radiotransmitter collars. Two different survival rates for those whose mortality mode was switched on and for those whose fate was unknown, was then calculated.
The results show that the minimum number of females increased from one in 1988 to 6 in 2000, there was then a decline in 2001 to only 2. Simple correlation analysis showed that there was a strong connection between the estimated number of adult females and visitor observations. The article showed that they experienced a trapping success of only 42 captures out of a total of 1763 attempts. It is believed that 90% of the total bear population which resided within the Chisos Mountains was captured between 1988 and 2000, as in 1999 22 bears were known to be alive, this then rose to29 bears in 2000. During the autumn of 2000 a large dispersal event was recorded, 10 bears left Big Bend national Park and headed in the direction of Mexico. They travelled 47-128km from the park. Dispersal ranges averaged 76.1±33.9 for females and 92±15.4 for males. One adult female succeeded in migrating to the Sierra del Carmen and back again and was in the process of a second journey when her collar switched to mortality mode. It is thought that she either slipped off her collar, as she had done this previously, or she died of natural causes. 3 of the bears whose collars had switched to mortality mode were near Ejidos towns, poaching was believed to be the cause but was never proven. They were not able to recover all of the bears and it is believed that they had ventured far enough into Mexico, that
Show More

Related Documents: Dynamics Of A Black Bear Population Within A Desert Metapopulation

Impact Of Climate Change

impacts Main article: Economic impacts of climate change Aggregating impacts adds up the total impact of climate change across sectors and/or regions.[126] Examples of aggregate measures include economic cost (e.g., changes in gross domestic product (GDP) and the social cost of carbon), changes in ecosystems (e.g., changes over land area from one type of vegetation to another),[127] human health impacts, and the number of people affected by climate change.[128] Aggregate measures such as economic…

Words 427 - Pages 2

Climate Change In California

deforestation, and technology are all factors when it comes to climate change. This issue is significant to me due to the fact that I was born and raised in California, and the recent drought there can be linked to global warming. Every day more and more CO2 is released and the world is becoming warmer and warmer. However, there are steps that people can take to counter the devastation these gases will cause. One of the causes of climate change includes electricity production which is responsible for…

Words 559 - Pages 3

Climate Change Essay

Natalie Sesco English 1 Uri Hertz May 17, 2012 Environmental Issues Everyone talks about climate change and how the Earth is slowly deteriorating, but no one seems to have specific examples. In Linnea Saukko’s “How to Poison the Earth,” she does use specific examples of what is causing climate change. She uses satire with a hint of sarcasm in her essay. She gives the reader specific examples of how to poison the Earth, but not really wanting to poison the Earth…

Words 1131 - Pages 5

climate change Essay

climate change is an issue that is affecting people all over the world. Climate change From Wikipedia, the free encyclopedia For current and future climatological effects of human influences, see global warming. For the study of past climate change, see paleoclimatology. For temperatures on the longest time scales, see geologic temperature record. Page semi-protected Atmospheric sciences ShipTracks MODIS 2005may11.jpg Atmospheric physics Atmospheric dynamics (category) Atmospheric chemistry…

Words 7672 - Pages 31

Climate Change Essay

The Climate Change Debate 1. Article Review – ‘Perception of Climate Change’ by Hansen et al. This article investigates the phenomena climate change and its aim is to use statistical data to support that climate change is real. An aspect of climate change named as ‘climate dice’ is mentioned in the article which referred to the chance of extreme weathers such as unusually cool or warm seasons. In the past three decades, there has been evidence of increasing climate dice ‘loading’ occurring…

Words 3088 - Pages 13

Climate Change Essay

“We have to face the reality of climate change. It is arguably the biggest threat we are facing today.” (William Hague). Climate change is the change in the patterns of the global climate, caused by the increase levels of carbon dioxide that are produced. The tropical forests that are being destroyed and the fossil fuels that are used every day are two of the causes of the large quantities of carbon dioxide that are released into the atmosphere. Climate change is an issue that affects us all and…

Words 919 - Pages 4

Hurricane Climate Change

live in the states such as Texas and Florida need to understand why climate change has had a tremendous impact on the ferocity that these hurricanes have hit their homes. Additionally, citizens of states like Florida and Texas also need to learn the emotional and economic impact that a storm can have on families. There is always opposition about climate change, however, it is time for people to realize that because of the climate change that our world is undergoing, these people will see more dangerous…

Words 619 - Pages 3

The Importance Of Climate Change

limate change is any long-term significant change in the “average weather” that a given region experiences. Average weather may include average temperature, precipitation and wind patterns. It involves changes in the variability or average state of the atmosphere over durations ranging from decades to millions of years. These changes can be caused by dynamic process on Earth, external forces including variations in sunlight intensity, and more recently by human activities. Climate changes reflect…

Words 694 - Pages 3

The Importance Of Climate Change

Earth has been through many changes in its climate. The Earth has gone through continental shifts, ice ages, and warm spells. One of the first issues with climate change is greenhouse gases. Greenhouse gases are released through humans, factories, vehicles, and animals. Even the dinosaurs have released methane into the atmosphere. Oceans currently release methane into the atmosphere. Since the birth of industry around the world and destruction of natural resources the climate of Earth has been rapidly…

Words 716 - Pages 3

climate change Essay

Climate change has become an important issue all over the world. With the heavier situation appearing in the earth, a large amount of problems shows up. Climate change refers to the important and continuous change in global climate patterns ranging from decades to millions of years which are put down to the increased levels of atmospheric carbon dioxide produced by using fossil fuels (Wikipedia). Climate change not only largely affects the nature but also influences the society. This essay outlines…

Words 907 - Pages 4