One of my purposes for this site is to share some of the observations I make during the banding projects in which I participate. While I've been extremely careful with my data-collection and protocols, costs and other resource issues create major differences between my work and "full-blown" scientific studies. Still, I find a lot here that's interesting, and I hope you do too:
Migration Patterns
Though hummingbirds definitely migrate individually, my relatively small sample of banding data confirms a pattern consistent with previous research: Males precede females, and mature birds lead immatures.
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Take a look at the graph at the right. It represents data I collected at two banding exhibitions at the same site three weeks apart in September of 2003 (the Folsom Hummingbird Festival on the 6th and the Folsom Butterfly Festival on the 27th, both at Mizell Farms, Folsom, Louisiana). The first two columns are males and females, respectively, banded on the first date. (The top box is immatures, the bottom adults.) The third and fourth columns are the same breakdowns for the second date, exactly three weeks later.
Note: There are many variables -- such as weather, minor changes in habitat (available food resources), and such -- interlaced with these data but not accounted for in these simple conclusions.
What do we see?
• Overall, the number and proportion of males trapped on the second date declined dramatically from those captured three weeks earlier. The opposite is true for the females; their numbers and proportion of the total increased.
• Also, see how the proportion of immature birds (the top slice) increases for both males and females on the second day.
The primary trend is clearly that males migrate ahead of females, and, secondarily, mature birds lead immatures.