Hello my name is Mrs. Deacon. Please join me as I travel to Nova Scotia to study the ecology of mammal populations.

Monday, October 4, 2010

Analysis of Data Collected

      In order to collect usable data, we can use many different techniques in the field.  We can begin with observation of the organisms in the study.  Depending on the organism, it may be difficult to observe much of the population.  If observation is letting you down, you can look also look at field signs.  Field signs include Scat / Poo (which scientists now can use DNA to determine the type of animal), tracks, burrows, feeding remains, damage to trees, calls / vocalizations, hair / other shed “bits” (ex: antlers from deer), dead animals – most you find as road traffic accident, and smell.

Deer prints

Beaver Dam

Beaver damage

Porcupine Scat

     Finally, we can set up traps.  We here in Cook's Lake, have set up two types of traps: live traps and camera traps.  The first type, live traps can allow us to measure the animal, assess its health, take samples from the animal, find the sex of the animal, and mark as an individual. A camera trap does not inconvenience the animal at all and does not stress the animal.  We may be able to see the animals behaviorand numbers, and camera traps are not  as much labor as live traps, but they are very difficult to recognize individual animals.
     The purpose of these methods is to estimate an organisms population within an area.  With the live traps, we have been using the "Mark - recapture method" to estimate the size of the wildlife population.  The formula we use to extrpolate the population is called the "Lincoln - Peterson Model", which is as follows:

[(N+R)/R] x M=Population estimate

where: N = new captures, R = recaptures, and M = marked.
So therefore, using this formula, we are able to figure...

Capture site #1: Hardwood Brush

Chipmunk [(0+1)/1] x 4=4
Deer Mice [(1+2)/2] x 4 = 6

Total [(1+3)/3] x 8 = 10.6 / half hectare or 25 / hectare

Capture Site #2 : Forest

Chipmunk [(1+1)/1] x 1 = 2
Deer Mouse [3+1)/1] x 4 = 16
Red Backed Vole [(2+3)/3] x 5 = 8.3
Bog Lemming [(1+0)/0] x 1 = 2

Total [(7+5)/5] x 11 = 26.4 / half hectare or 53 / hectare

What does this data tell us?  Define the term density. What is the density of each of the populations sampled? What are four factors that may impact the density of a population? 

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