[Bristol-Birds] Fw: Humming bird populations banding numbers

  • From: "Wallace Coffey" <jwcoffey@xxxxxxxxxx>
  • To: "Bristol-birds" <bristol-birds@xxxxxxxxxxxxx>
  • Date: Wed, 14 Jul 2010 20:27:23 -0400

In a message dated 7/14/2010 5:31:17 A.M. Central Daylight Time,  Jerry Butler 
grandoc@xxxxxxx writes:
        After our lively discussions on ARbird [Arkansas Bird List] about  RTHU 
[Ruby-throated Hummingbird] populations, I e-mailed Danny Bystrak of the bird 
banding lab and asked him a few questions re the number of hummingbird banders 
, the banding locations and the extent of the effort in bird banding for the 
last three years.  His answer was informative for me, and I thought it would be 
helpful to others as well.  I have attached his answer addressed to me.

        Hi Jerry, 

                It would be very difficult to get the exact number of locations 
in which hummers were banded in a given year, but I just checked the 2009 data 
and there are 287 latitude-longitude coordinates.  Each one may represent only 
one location or many.  The way we store the data, it is difficult to tell.  But 
there are definitely at least that many locations.  Number of banders is 
easier.  In 2009 there were 49 banders who have submitted banding data on 
hummers.  Among the 49 there are certainly subpermittees as well, so that 
number also is going to be slightly higher.  As I have mentioned before, there 
are still data that have not been submitted for 2009 yet, so these are 
preliminary numbers, which, unfortunately, may not be final for several years. 

                Regarding change in effort, my impression is that hummingbird  
banding has increased in popularity and I doubt if there has been a decrease in 
effort in the last three or four years.  As far as number of hours or days 
spent banding, that would be a nearly impossible number to come up with, and 
the best we could do would be a wild estimate. 

                Generally numbers of birds banded cannot be correlated to 
relative abundance of birds except on the very grossest levels.  An example of 
how misleading banding numbers can be in this regard is among the endangered 
species.  As soon as a species is officially listed as endangered there is 
suddenly money available to study them.  This translates to lots of banding in 
most cases.  So some of the rarest species in North America actually have very 
large numbers of bandings. 

                I wouldn't worry about impressions of decline in the last three 
years.  First, impressions are often inaccurate and second, most species' 
populations change in a cyclical  pattern anyway, with downward trends followed 
by upward ones.  With the massive increase in hummingbird feeding, it is highly 
unlikely that their populations are down from what they were several years ago. 
 These are my impressions anyway. 


        Danny Bystrak
        Wildlife Biologist
        Bird Banding Lab
        Patuxent Wildlife Research Center


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