resource for overseas and beginning birders

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Subject: resource for overseas and beginning birders
From: "Paul & Irene Osborn" <>
Date: Tue, 31 Jul 2007 12:31:10 +1000
For my personal bird records I use a system that could provide some of the information required, i.e. the likelihood of seeing a particular species in a particular spot. Rather than just recording what birds I've seen where, I record the date I first saw the bird there and subtract one less than the date that I arrived. So if I saw the bird on the first day, it gets a score of 1. Over a long enough time, or a large enough number of visits by birders, the data can be averaged out to provide an approximation of probability data. For my home list, where I am present most days, the data is now large enough to give fairly good approximations of the likelihood of seeing any species. For any species not seen in the month, I give a score of 32. Thus, if the bird is never seen, it will have an average score over time of 32. If it is a rare vagrant, seen once, it will end up with a score of 31 point something. Magpies etc. that are seen nearly every day, end up with a score close to 1. Once the number of observation days is high enough the data can be subdivided and averaged such as to give a likelihood for any month of the year, so migrants will have a high score in June and a low one in November. At the moment, my personal data is only extensive enough to give reliable likelihood estimates for places I vist (or have visited) often. If all birders took up my system, I think it would go a long way to providing the sort of information that the originator of this thread wanted.
Paul Osborn


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