HUMMINGBIRD BANDING DATA
from the Rudeen Ranch, Power County, Idaho

Memorial Day Weekend Banding Only

CHARTS AND GRAPHS

Average Recapture Rates by Species

Each year we get new data for recaptured birds that have been banded in previous years. Birds banded as adults in one year are called "ASY" (After Second Year) birds when they are encountered the next year. Similarly, birds banded as adults 2 years prior to recapture are called "ATY" (After Third Year) birds when they're recaptured. Since we began banding annually in 2003, we've collected a fair dataset of "ASY" recaptures (birds banded the previous year) that have returned -- and of course progressively fewer datasets of ATY, A4Y, and older birds.

Memorial Day Weekend 2007, for instance, was the first year we were able to classify "A5Y" (After Fifth Year) birds -- those birds originally banded in 2003. But in 2007 we also were able to recapture "A4Y" birds (those originally banded in 2004), "ATY" birds (those originally banded in 2005), and of course "ASY" birds (those originally banded in 2006).

So what does the graph below show us? Well, based on the graphed data, we expect around 30% of the birds we banded the previous year to be encountered as "ASY" birds. Remember that the "n" (or sample size) is progressively smaller for birds which fall in an increasing age class. For instance, in 2007, we had already seen 4 years worth of "ASY" data from which to compute those averages, but that was the first year for which "A5Y" age classes were available. Continue scrolling down this page to see charts of the individual years' recapture rates for each age class from which these averages were computed.

Recapture rates are presented as a percent of the total number of that species banded during the year in question. For this page, only the birds banded and recaptured during Memorial Day Weekend trips are included. In several years, banding sessions occurred later in the summer and into the fall. Birds banded during those events are not included in this analysis, but are listed in others.

ASY -- After Second Year Recapture Rates

Each year we recapture a certain percentage of birds banded the previous year. These are given the age class "ASY" (After Second Year). Their recapture rates each year are shown below.

ATY -- After Third Year Recapture Rates

Beginning in 2005 and each year thereafter, we were able to document returns of bird banded as adults two years prior (called "ATY" birds).

A4Y -- After Fourth Year Recapture Rates

Birds banded as adults in 2003 would be "A4Y" (After Fourth Year) when recaptured in 2006. Recapture rates for that age class beginning in 2006 are shown below.

A5Y -- After Fifth Year Recapture Rates

This age class began to be available in 2007 -- for birds banded as adults in 2003. Each subsequent year will produce another population of "A5Y" birds to study and document.

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