Harbour seal reproductive rates

[cordes]

I want to estimate reproductive rates of harbour seal females using MARK, however, I am not sure how to do this.

During my PhD I have carried out an individual-based study on the reproductive ecology of harbour seals. I have 5 years of resightings data (photo-ID) of 73 female harbour seals using one sandbank. Within each of the five years I have between 50-65 photo-ID surveys over the pupping season (May-July). Photographs are used to record whether the female was seen on a particular day and whether or not she was seen with a pup, all of which is entered in a capture history. Recapture rates of females are very high both within pupping season and between years. However, each year there are a few females who are only seen a couple of times and there is some uncertainty regarding whether she had a pup or not.

Harbour seal females generally give birth to one pup each year (they also skip years) which is weaned quite quickly.

Do you have any suggestions on how to estimate reproductive rates using MARK? Is there a simple way of analysing this, and then perhaps a more complicated way which takes into account the uncertainty regarding a female's breeding state if she was not seen very often.

[cooch]

I want to estimate reproductive rates of harbour seal females using MARK, however, I am not sure how to do this.

During my PhD I have carried out an individual-based study on the reproductive ecology of harbour seals. I have 5 years of resightings data (photo-ID) of 73 female harbour seals using one sandbank. Within each of the five years I have between 50-65 photo-ID surveys over the pupping season (May-July). Photographs are used to record whether the female was seen on a particular day and whether or not she was seen with a pup, all of which is entered in a capture history. Recapture rates of females are very high both within pupping season and between years. However, each year there are a few females who are only seen a couple of times and there is some uncertainty regarding whether she had a pup or not.

Harbour seal females generally give birth to one pup each year (they also skip years) which is weaned quite quickly.

Do you have any suggestions on how to estimate reproductive rates using MARK? Is there a simple way of analysing this, and then perhaps a more complicated way which takes into account the uncertainty regarding a female's breeding state if she was not seen very often.

Start with the following, and reference cited therein. This (and a number of similar papers) address this very topic (more or less).

Kendall, William L., James E. Hines, and James D. Nichols. 2003. ADJUSTING MULTISTATE CAPTURE–RECAPTURE MODELS FOR MISCLASSIFICATION BIAS: MANATEE BREEDING PROPORTIONS. Ecology 84:1058–1066.

[cordes]

I have actually read this one (as well as Kendall et al. 2004). Does the model they used in MSSRVmis correspond to the "Robust Design MultiState with misclassification" in MARK?
If so, in the capture history are there then three states: B=breeder, N=nonbreeder, and U=Unknown (unknown whether this female had a pup or not)?

Thanks for your help.

[cooch]

I have actually read this one (as well as Kendall et al. 2004). Does the model they used in MSSRVmis correspond to the "Robust Design MultiState with misclassification" in MARK?

I believe so...

If so, in the capture history are there then three states: B=breeder, N=nonbreeder, and U=Unknown (unknown whether this female had a pup or not)?

Thanks for your help.

...but at present, that data type (and how it is implemented in MARK) is 'undocumented', so I'll leave it to Bill to answer when he gets a chance.