[Basta-users] post-fledging survival - Julian day or capture days for input format?

[Diederik Strubbe]

Dear BaSTA community,

 

I am involved in a radio-tracking study on survival rates of tropical
birds after fledging. Birds were followed from fledging until
independence (about two months for each bird). My main question is about
how to organize a data frame for input. As not all birds fledge at the
same moment, when using Julian days as input, after 60 days of tracking,
birds are assigned a 0 value – because we stopped looking for that
bird.  So, for example, on Julian day 312 a 0 can indicate either that
we did not find the bird on that day, or that we had stopped searching
for it.

 

Can I arrange that data so that ‘birth’ (here: day of fledging) =1 for
all birds, and all following days are numbered from 2 to 61. So, for
example, in this arrangement, day 15 [the 15^th day of tracking] refers
to November 17^th for birds that fledged on November 2^nd , but to
November 29^th for birds that fledged on November 14^th .

 

I should also note that although about half of the birds have only been
seed at fledging (on day 1, but no observations in the following 60
days), we did not find any dead birds either. I assume the most
conservative manner to treat this is to set all ‘deaths’ [i.e.
independence of juvelines = end of tracking period]?

 

Many thanks in advance for any comments or suggestions.

 

Best wishes,

 

Diederik

-- 
Dr.Diederik Strubbe
Evolutionary Ecology Group
Department of Biology
University of Antwerp
Middelheimcampus GV310
Groenenborgerlaan 171
2020 Antwerpen, Belgium
office: +32 3 265 34 69
mobile phone: +32 477445568
skype user name: lakrinn

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.r-forge.r-project.org/pipermail/basta-users/attachments/20150803/a01d462f/attachment.html>