# ecosystems questionWatch

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#1
I'm having trouble with how to answer this one, I spent 5 minutes trying to work out what its asking me to do, and I had written an answer. But, the mark scheme confuses me. Here it goes,

Blue tits are common British birds. Some aspects of the behaviour of blue tits at different times of the year are summarised below.

April-July Breeding season. Eggs laid and young hatch. Adult birds collect food for their young from within their territories.

(it does have different parts of the year but I dont think its necessary for the question)

question (a) and (b)(i) were about the mark-release-recapture technique. I didnt have a problem with these, but (b)(ii) was this

Suggest how the population of adult blue tits in a wood might be estimated between April and June.

The mark scheme says this, and I quote this

Approach valid;
Gives reliable estimate of number of adult blue tits; 2

Help please, I have no idea what the mark scheme means. My answer for this question was 'Set traps which only tag the birds, not capture them, traps must contain food for the adults young'

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8 years ago
#2
N=(m x c)/r
M= total no. In first sample
C= total no. In second sample
R= number of marked individuals in recaptured sample
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8 years ago
#3
To elaborate on my answer I beleve they are asking you to use this formula which is the formula which you need to estimate the population size once you've done the sampling.
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#4
(Original post by macroscopic)
To elaborate on my answer I beleve they are asking you to use this formula which is the formula which you need to estimate the population size once you've done the sampling.
Sorry, I wasnt clear in explaining this, thats what was wanted in the first parts of the question. The first one (a) was 36 trapped in first one and marked, then 43 were trapped, of these 43, 21 were ringed. Estimate the size of the population, so yes like you said its (36 x 43)/21.

(b)(i) said give two reasons why the mark-release-recapture technique would not give a reliable estimate of the blue tit population in a wood between April and June.

I had no problem with them 2, but they're both about the mark-release-recapture method, is the last question a trick one? These sort of questions annoy me, and even the mark scheme doesnt help

Thanks for trying to help
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