Ecologist without maths brain needs help!

ecologist

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Sep 13, 2016
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HiMy first visit to the site and it concerns a threatened species (bettong). bettongs live in warrens in groups of 4. If we moved 351 bettongs from warrens into a new area (just released the bettongs on the ground surface) and then retrapped at warrens afterwards at the new site what is the probability that a bettong will be sharing with one of the same warren mates from before? The number of bettongs per warren is 4 before and 4 after the move. We only recaptured 100 bettongs afterwards but released 351. So is the probability of a bettong sharing with one other member according to chance = 3/351 * 3 and then you times by 100 to get the number of bettongs expected to be sharing in the new sample? Appreciate any advice on this as we had 12 sharing afterwards (6 pairs) out of 100 so I am trying to work out if this is more or less sharing than expected by chance.
 
Q: Bettongs live in warrens in groups of 4. If we moved 351 bettongs from warrens into a new area (simply releasing the bettongs on the ground surface) and then re-trapped at the new warrens afterwards at the new site, what is the probability that a given bettong will be sharing a given warren with one of its warren mates from the original warren?

The number of bettongs per warren is 4 before and 4 after the move. Only 100 bettongs were re-trapped.

My answer: We only re-captured 100 bettongs afterwards but released 351 originally. So is the probability of a bettong sharing with one other member according to chance = 3/351 * 3 and then you times by 100 to get the number of bettongs expected to be sharing in the new sample? Appreciate any advice on this as we had 12 sharing afterwards (6 pairs) out of 100 so I am trying to work out if this is more or less sharing than expected by chance.
What other assumptions does this exercise expect you to make? For instance, are we to assume that bettongs that don't know each other (at the original site) will fight before (possibly) settling down together? Or are we to assume that the animals take no account of each other's smells, past experiences, etc, and are, effectively, in a "blank slate" situation? What information did they give you about the hundred re-trapped animals? How are you expected to integrate this information?

Please be complete. Thank you! ;)
 
more info

I think it would be good to assume there are very few assumptions! ie bettongs are just as likely to share with a previous warren conspecific as a new animal, they are not put off by smell and all bettongs have an equal chance of accessing each other in the new pen. Only 36 warrens were located afterwards so we only retrapped 100 animals but we can assume we recaptured all animals from those warrens as the average no. of bettongs per warren before and after was the same. So we assume the other 251 bettongs that were not trapped are living in other warrens with individuals from the release. Hope that gives enough information?
 
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