Estimating passage population size, without using count data

[jelle]

Dear all,

I have used the MARK book to teach myself MARK gradually over the past year and have become stuck on a population size estimation for relatively small waders on staging site, during autumn migration.

In my study-area birds are immigrating and emigrating throughout time, in order to calculate the staging time and to correlate this with weather conditions and individual differences I am collecting daily resightings. Besides we are performing daily high tide counts in order to make an estimation of all the birds present in the area, at the same time we are also estimating the density of marked individuals within the birds around.

One simple way then to estimate the total passage population size is to correct daily counts for the emigration probability (calculated with SODA). However as small waders are hard to count, the presence of predators and the water-level is influencing how many waders are present on the high tie roost, I found it not the most the optimal way to calculate the total passage population size.
Therefore I was thinking about a ‘new’ way to calculate this. While the simple Lincoln-Petterson estimator can’t be used to calculate the population estimation (We are dealing with an open study-area whereby birds are immigrating and emigrating throughout time). However by calculating the staging time we are actually able to make an estimation of the number of marked individuals present. Together with the density of marked individuals in the population and the birds resighted on every day it is then possible to calculate the population size for each consecutive day with the Lincoln-Petterson estimator. In order to calculate than the total population size, we can correct the daily estimation for birds that were already present in the study-area.

My question is then does anybody have an idea to calculate the confidence intervals or does anybody knows a good book/manual describing how to calculate this.
And off course if there is another solution for calculating the population size without using the count! data you are free the give me a hint.
With kind regards,
Jelle

[dhpstroud]

You could use the POPAN model in MARK if you have individuals uniquely tagged and you are able to create encounter histories rather than counts. POPAN will give you phi (apparent survival), p (capture probability given the animal is alive and on the study area, i.e., available for capture), pent (probability of entry into the population for this occasion), and N (super-population size) for each sampling occasion. It's very user friendly.

[dhpstroud]

Oh, and the output automatically gives you the standard error and confidence intervals for each parameter.