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Endangered Species

Discussion of the distribution and abundance of living organisms and how these properties are affected by interactions between the organisms and their environment

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Endangered Species

Postby bearhug » Wed Jan 25, 2006 3:31 pm

What makes a species endangered? What I mean is what percent of the species population has to be gone or what number of their current population classifies them as endangered?
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Postby baikuza » Thu Jan 26, 2006 3:45 am

because they are have a risk to be dissapear from this world, i.e earth. because they are extinct. their do not have many population on/in this earth.

"Extinction (Also see the introduction to Past Extinctions) The state in which all members of a groups of organisms, such as a species, population, family or class, have disappeared from a given habitat, geographic area, or the entire world." (http://www.bagheera.com/inthewild/class_glossary.htm)

maybe we can say, it is only 100 and the multification. not more than 1,000. (i think)
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Postby Dr.Stein » Thu Jan 26, 2006 6:32 am

Here is the official and complete criteria of how a species is included to "endangered"
(based on IUCN Red List System or "The Redbook"):

happy reading ;)

ENDANGERED (EN)

A taxon is Endangered when the best available evidence indicates that it meets any of the following criteria (A to E), and it is therefore considered to be facing a very high risk of extinction in the wild:

A. Reduction in population size based on any of the following:

1. An observed, estimated, inferred or suspected population size reduction of >=70% over the last 10 years or three generations, whichever is the longer, where the causes of the reduction are clearly reversible AND understood AND ceased, based on (and specifying) any of the following:
(a) direct observation
(b) an index of abundance appropriate to the taxon
(c) a decline in area of occupancy, extent of occurrence and/or quality of
habitat
(d) actual or potential levels of exploitation
(e) the effects of introduced taxa, hybridization, pathogens, pollutants,
competitors or parasites.

2. An observed, estimated, inferred or suspected population size reduction
of >=50% over the last 10 years or three generations, whichever is the longer, where the reduction or its causes may not have ceased OR may not be understood OR may not be reversible, based on (and specifying) any of (a) to (e) under A1.

3. A population size reduction of >=50%, projected or suspected to be met within the next 10 years or three generations, whichever is the longer (up to a maximum of 100 years), based on (and specifying) any of (b) to (e) under A1.

4. An observed, estimated, inferred, projected or suspected population size reduction of >=50% over any 10 year or three generation period, whichever is longer (up to a maximum of 100 years in the future), where the time period must include both the past and the future, and where the reduction or its causes may not have ceased OR may not be understood OR may not be reversible, based on (and specifying) any of (a) to (e) under A1.

B. Geographic range in the form of either B1 (extent of occurrence) OR B2 (area of occupancy) OR both:

1. Extent of occurrence estimated to be less than 5000 km2, and estimates
indicating at least two of a–c:
a. Severely fragmented or known to exist at no more than five locations.

b. Continuing decline, observed, inferred or projected, in any of the following:
(i) extent of occurrence
(ii) area of occupancy
(iii) area, extent and/or quality of habitat
(iv) number of locations or subpopulations
(v) number of mature individuals.

c. Extreme fluctuations in any of the following:
(i) extent of occurrence
(ii) area of occupancy
(iii) number of locations or subpopulations
(iv) number of mature individuals.

2. Area of occupancy estimated to be less than 500 km2, and estimates
indicating at least two of a–c:
a. Severely fragmented or known to exist at no more than five locations.

b. Continuing decline, observed, inferred or projected, in any of the following:
(i) extent of occurrence
(ii) area of occupancy
(iii) area, extent and/or quality of habitat
(iv) number of locations or subpopulations
(v) number of mature individuals.

c. Extreme fluctuations in any of the following:
(i) extent of occurrence
(ii) area of occupancy
(iii) number of locations or subpopulations
(iv) number of mature individuals.

C. Population size estimated to number fewer than 2500 mature individuals and either:

1. An estimated continuing decline of at least 20% within five years or two
generations, whichever is longer, (up to a maximum of 100 years in the
future) OR

2. A continuing decline, observed, projected, or inferred, in numbers of
mature individuals AND at least one of the following (a–b):

a. Population structure in the form of one of the following:
(i) no subpopulation estimated to contain more than 250 mature
individuals, OR
(ii) at least 95% of mature individuals in one subpopulation.

b. Extreme fluctuations in number of mature individuals.

D. Population size estimated to number fewer than 250 mature individuals.

E. Quantitative analysis showing the probability of extinction in the wild is at least 20% within 20 years or five generations, whichever is the longer (up to a maximum of 100 years).


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Endangered is one of nine criteria described by IUCN. If you want to know the rest, I can send you the book as I have it. Just let me know :)

Nowadays I am into conservation thing. What a nice hell! :) Time for you to go out from your nest for a while, Dr.Stein hehe ;)
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Postby playboy bunny » Sat Jan 28, 2006 9:13 pm

DID YOU COPY THAT OF THE INTERNET DR STEIN?
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Postby Alish24 » Fri Feb 03, 2006 12:15 pm

its very nice to see you in the conservation efforts Dr. Stein :)
I ve been also working in a project for Sea Turtles conservation projects since 2000!! as u know Sea Turtles are also an endangered species throughout the world!
anyway I think everyone can find the criterias about endangered species from IUCN s website!
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Postby Dr.Stein » Sat Feb 04, 2006 2:41 pm

Alish24: Hey, maybe you know my sister? She is into Sea Turtles Project too ;) Basically I use to "exploite" seahorses for medicine :oops: :P (to be precise: explore) Naah, I take a responsibility to do a campaign for conservation as well thru Project Seahorse :)

playboy bunny: It is from IUCN Red List Criteria Book, also available in downloadable PDF. Hey, please avoid using all caps thingy, that's rude ;)
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