Subject: Louisiana Hummingbird Banding - Winter 2001-2002|
From: Nancy L Newfield colibri@WEBDSI.COM
Date: Fri, 12 Apr 2002 09:56:19 -0500
Louisiana Hummingbird Banding - Winter 2001-2002The following is a summary of the hummingbird banding activities of Dave Patton, Linda Beall, Mark Myers, and Nancy Newfield over the course of the 2001-2002 winter season. Patton, Beall, and Newfield are self-employed, permitting some flexibility in scheduling, but none was able to dedicate all of their time to the project. Myers is the curator of birds at the Audubon Zoo. He recently began banding hummers and looks forward to learning more about the wintering hummers.
Most hummers were banded in the southern third of the state, roughly the area south of the Interstate 10/12 line. Patton covered the area from Baton Rouge westward, while Newfield covered Baton Rouge eastward, excepting St. Tammany Parish, which was primarily covered by Beall. St. Tammany Parish was covered by Newfield prior to Beall's entry into the ranks of humbanders. Patton, Beall, and Newfield all banded in Baton Rouge and probably caught only a fraction of the hummers around. Patton also covered a small pocket of wintering hummers in the Shreveport area, far removed from the hotbed of other wintering hummers.
The Louisiana Winter Hummingbird Project differs substantially from passerine migration banding studies. Most sites host only a few hummers, so efforts must be made to catch individuals rather than mist-netting whichever birds might pass through. Most captures are made using cage wire traps placed around a feeder. Mist nets and other types of traps are occasionally employed. Almost all birds were color-marked, using non-toxic acrylic paint on their crowns. Color-marking allowed us to avoid repeatedly capturing the same birds and it permitted hummerhosts to specifically identify each individual. Color-marking enabled the hosts to distinguish look-alikes and to notice new birds as they appeared. In several locations, we found more individuals present than had been originally tallied by the hosts. In most locations, the roster of individual hummers did not remain constant. Instead, while a few individuals defended territories throughout the winter, many seemed to be trap-lining over a fairly large area. This required the banders to make two or more visits to a number of sites as new birds replaced individuals that had already been banded.
This project was initiated in 1979 as a means of documenting the numbers and species assortment of hummingbirds that spend the winter months in Louisiana. Traditional wisdom of the 1970s was that any hummers occurring during the winter months were vagrants or they were Ruby-throated Hummingbirds that forgot to migrate after the nesting season. In the 1970s, most guides to hummingbird feeding dictated that feeders should be removed by early September so that the ready availability of nectar would not cause hummingbirds to linger too long into the fall. At that time, it was thought that nearly all wintering hummers perished to cold weather.
The season, as we define it, begins with the arrival of the first non-Ruby-throated Hummingbird in late summer. Typically, the first arrivals are adult Rufous Hummingbirds in August and most are returnees from previous seasons. During the early part of the season, we primarily attempt to verify returning hummers. Later, as several birds stake out territories at a site, we try to capture and band as many as possible.
Because the last stage of Ruby-throated southward migration extends well into December, it is very difficult early in the winter banding season to categorize individuals of that species as winterers or migrants. Therefore, we arbitrarily define wintering for Ruby-throateds as those we encounter on or after 15 November, though some of those birds may actually be tardy migrants.
The winter banding season peaks in January and February, when maximum numbers are present at the various sites. The season usually ends in late February or early March as wintering birds begin leaving and summer resident Ruby-throateds begin arriving. At that time, wintering birds become more difficult to catch and banding trips become less productive, though some wintering birds stay well into April or even early May. However, this season many individuals remained by late March and banding continued until the month was nearly over.
Totals for the 2001-2002 season are:
This is the largest number of wintering hummingbirds ever documented in Louisiana. The previous high count, documented in 2000-2001, is 416 individuals of 8 species + 32 returnees + 3 foreign re-encounters. It is not clear whether the number of hummers spending the winter months is increasing or if methods of finding them have improved markedly. The concepts of "better networking" versus "actual increase" can be debated endlessly. Both factors are probably at work. Certainly, the network of hummingbird hosts has expanded greatly with better communications, particularly through Humnet. However, several gardens hosted remarkable numbers and diversity for a winter season in the eastern United States.
As usual, Rufous comprise the largest number of individuals, accounting for almost two-thirds of the birds handled. Over the past few years, the percentage of Rufous among the total population has risen steadily. At the same time, the percentage of wintering Ruby-throateds, which had shown a marked increase in the last year, plummeted. Perhaps the 2000-2001 season was aberrant and the most recent season was a return to normalcy. Yet, there were more returnees than ever before.
Black-chinned numbers rose modestly, while Buff-bellied tallies remained about the same. Disappointingly, several multiple-year returnee Buff-bellieds failed to return this season. Calliope numbers also remained static, though the number of returnees of this formerly rare species was the best recorded.
Two relatively rare species made good showings this season. Broad-tailed numbers were 5 times their total from last season and Allen's numbers were more than 6 times that of last season. A returnee Allen's was the first returnee ever recorded in Louisiana.
Broad-billed numbers were also very good. This species, added to the state list in 1990, seems to be showing an increase comparable to those shown by Buff-bellieds in the 1980s and Calliopes in the 1990s. Factors effecting these changes are certainly elsewhere rather than in Louisiana.
Additionally, 4 Rufous that were banded in Louisiana in previous seasons were caught by banders in other states - Alabama, North Carolina, Missouri, Mississippi. The Mississippi-caught bird was already an adult when banded in Baton Rouge in January 1996. This would put her putative hatching date as June 1994 or earlier, using the standard Bird Banding Laboratory formula for estimating age.
A Rufous banded in Alabama in the 2000-2001 season was captured in Lafayette. Another Rufous banded the previous season in Baton Rouge chose to spend the winter in Lafayette as well. These guys must long to hear zydeco during the breeding season.
A Ruby-throated that previously wintered in Metairie met a sad fate when he struck a glass door in Thibodaux in December.
Returnees are the heart and soul of the project. They prove winter survival, indicate wintering site fidelity, and give us data concerning longevity. The oldest returnee this season was a female Rufous that was an adult when banded in January 1997. She has returned to the same yard in Abita Springs every year since.
Another old-timer was a male Ruby-throated that also was an adult when banded in LaPlace in December 1997. He was originally encountered at a site more than 1/2 mile away, but has wintered in the same place for at least 3 years.
Weather can play a significant role in this project. We do not band during subfreezing temperatures or during heavy rain, but neither was a major factor this winter. Dense fog can impede travel, though at no time did it become dense enough to cause us to abandon a planned trip. Most of the region experienced frost and brief periods of freezing weather during late December and early March. These episodes reduced flowering of many tropical and subtropical plants, making hummers somewhat more dependent on feeders and thus more readily caught. Nevertheless, natural nectar and insects were available at all times. A male Broad-billed spent the entire season in a public garden in New Orleans and he was never observed using feeders at nearby homes.
While many winter hummers stay put, others are wanderers. A color-marked adult male Rufous that appeared in Covington in late January proved to be one that was banded in Thibodaux earlier in the month. He was still present at the second location two months later. The distance between the two sites is approximately 80 miles.
Other wanderers moved lesser distances. A banded, color-marked Black-chinned with a visibly damaged bill in River Ridge in early January was probably an individual that was handled in LaPlace in late December, but it was not captured to verify its band number. These two sites are about 15 miles from each other.
An immature female Rufous, banded in Mandeville in early December, was observed 8 miles away in Abita Springs three days after banding. She remained at the second site well into March.
At least a few hummers seem to be migrating during the height of the wintering season. A very fat immature male Ruby-throated was captured in Covington in the third week of January. He had not been seen prior to the day he was caught and was not seen afterwards.
Another highlight of the project came when a female Rufous that was banded in Lafayette in December 2000 was recovered in Black Creek, British Columbia in May 2001. It was the first Louisiana-banded wintering hummer found on its species' breeding ground and it was the longest ever point-to-point re-encounter of any banded hummingbird, a distance of nearly 2300 miles.
The Louisiana Winter Hummingbird Project has benefitted from the enthusiastic assistance and generosity of numerous people. Many hummerhosts opened their doors at ungodly hours and sustained us with strong coffee, juice, breakfast and lunch. Several maintained a running tally of birds in their cities or towns and set up banding day schedules for us. Others wrangled equipment, trapped birds, and recorded data. We thank James Beck, Lynn Becnel, Laurie Binford, Olga Clifton, Miriam Davey, Kay Drouant, Carol Foil, Bill Fontenot, Elizabeth Edwards, Steve Locke, Beth and Sammy Maniscalco, Rose and Jack Must, John and Margaret Owens, Lisa Robichaux, Gene and Edna Street, Tom and Eloise Sylvest, and Tommy Walker for the many hours they have invested in this project. We appreciate your special help - and we are already looking forward to next season!
PLEASE NOTE NEW E-MAIL ADDRESS
Nancy L Newfield
Metairie, LA USA