Subject: Louisiana Hummingbird Banding - Winter 2002-2003|
From: Nancy L Newfield colibri@WEBDSI.COM
Date: Fri, 18 Apr 2003 15:05:01
Louisiana Hummingbird Banding - Winter 2002-2003The following is a summary of the hummingbird banding activities of Dave Patton, Linda Beall, Mark Myers, Paul Dickson, Steve Locke, and Nancy Newfield over the course of the 2002-2003 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. Dickson manages a large business. Locke is a University of New Orleans graduate student who worked in tandem with Newfield much of the time.
Most hummingbirds 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 and Locke covered Baton Rouge eastward, excepting St. Tammany Parish, which was primarily covered by Beall. Patton, Beall, and Newfield all banded in Baton Rouge and probably caught only a fraction of the hummers around. Myers covered scattered areas around New Orleans and Slidell. Dickson 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 during a specific time period. Most captures are made using cage wire traps placed around feeders. 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 unbanded birds as they arrived. Color-marked birds are more noticeable as they moved from one site to another as well. 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 defend territories throughout the winter, many seem 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 unbanded 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. The Louisiana list of hummingbirds was 5 species in 1974!
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 hummers that attempted to overwinter in the area perished in cold weather and therefore spending the winter months in Louisiana was not a good strategy for survival.
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. We also attempt to capture marked birds that have moved in from other sites.
Because the last stage of Ruby-throated southward migration may extend well into December, it is very difficult to categorize individuals of that species as winterers or migrants early in the season. 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 and some that occur earlier may well be winterers.
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. This season many individuals remained by late March and banding continued until the month was nearly over. Then, surprisingly, a Black-chinned that had not been resident at a spring banding site was captured in mid-April. .
Totals for the 2002-2003 season are:
Explanation of terminology: Bird banders often use specialized terminology when discussing their favorite subject. Returnee a bird that has returned to the specific wintering site where it was banded after having been away for its putative breeding season. Foreign Re-encounter any subsequent capturing of a banded bird after it leaves the 10-minute block in which it was banded. A foreign re-encounter can be the capturing of one of our own birds at a distant site within Louisiana. The total of foreign re-encounters does not include several birds banded during the season that were re-encountered elsewhere as the season progressed. These will be discussed later in the report.
This number of wintering hummingbirds falls only one short of the previous season’s record-setting total. The previous high count, documented in 2001-2002, was 482 individuals of 8 species [+ 55 returnees + 2 foreign re-encounters]. However, the total of foreign re-encounters raises the total of birds handled to more than had been recorded the previous season. [To read previous Louisiana Hummingbird Banding Winter Reports, log on to http://losbird.org/ and scroll down to “Hummingbirds”.]
It is not clear whether the number of hummers spending the winter months is increasing or not. Certainly methods for finding them have improved markedly. And, the increase in banders allows better coverage. The concepts of "better networking" versus "actual increase" can be debated without resolution. Both factors are probably at work. The network of hummingbird hosts has expanded greatly and the practice of creating habitat for wintering hummers has become popular. Better communications, particularly through the listserv Humnet, has given us the means to reach more people interested in hosting hummingbirds during the winter months.
The diversity of species banded was one less than in the previous two or three winter seasons though single individuals of 2 species [Anna’s and Broad-billed] raised the number of species known to be present to 9, a remarkable number for anywhere in the eastern United States. There are now 11 species on the Louisiana list.
As usual, Rufous accounted for largest number of individuals. Over the past few years, the percentage of Rufous among the total population has risen steadily. This season that percentage was just shy of 60%, similar to last season.
The number of wintering Ruby-throateds was the highest ever, surpassing the winter of 2000-2001 by 27 individuals. By contrast, the number of Ruby-throateds banded during the spectacular season of 2001-2002 was a mere 15 with 4 additional returnees. This time, Ruby-throateds were more evenly distributed over the region than in the 2000-2001 season when they were concentrated in the southeastern section of the state. None of the returnees was known to be present during the summer months.
Black-chinned numbers dropped considerably from their previous record total in 2001-2002. Buff-bellied totals were very small compared to every year recently. Calliope numbers rose a little while Allen’s totals remained at last season’s high total. Broad-taileds were much more rare than in the previous season. However, a young male Broad-tailed, banded in Shreveport, stayed the entire season to become the first of his species documented in the northwestern sector of the state.
8 birds caught by banders in other states were banded in Louisiana in previous seasons. 5 Rufous, 2 Buff-bellied, and a Broad-billed were caught elsewhere Alabama , Michigan, Tennessee, Texas , and Colorado. A Rufous, banded in Lafayette in January 1996, returned to her second winter home in Knoxville, Tennessee. She was the oldest to be documented. A Rufous banded in January 2001 was caught in Michigan in November 2002. Not too surprisingly, 2 Buff-bellieds that had been banded in Louisiana were found in coastal Texas in early fall. Weirdest of all was a Broad-billed, a rarity in Louisiana, that was banded in Baton Rouge in January 2002. This bird was subsequently caught in Clifton, Colorado, in November 2002, becoming a first record for that western state!
Louisiana banders caught birds banded in other states as well. A female Rufous caught in Shreveport proved to be one banded in Alabama the previous year. Amazingly, that same individual was later recaptured in Alabama near the original banding site.
While many of the wintering hummers stake out territories and defend them all season, others are wanderers or actual migrants, even during the coldest months. This season, more than any other time, we documented birds moving from one location to another.
A Texas-banded Buff-bellied was caught at two sites in Lafayette. Then, after spending the entire winter in Cajun country, he was again caught at the original banding site, 316 miles from Lafayette, in April 2003. This site in Raisin, Texas, is the same one where one of the Louisiana-banded Buff-bellieds was found! 316
A color-marked immature male Black-chinned, banded in Dauphin Island, Alabama in early January, was caught in Slidell just 2 weeks later. It remained at the second site, 96 miles from the first, only a few days.
Another color-marked immature male Black-chinned was noted in Houston, Texas, in mid-February. This one had been banded in mid-January in River Ridge, a suburb of New Orleans. The distance between the two points is about 311 miles. It seems likely that each of these Black-chinneds was migrating at the time of each capture.
A color-marked immature male Ruby-throated that was banded in LaPlace in early December eventually found its way to Ocean Springs, Mississippi, 103 miles away, in late January. Another, banded the same time and place, ended up 29 miles distant in Thibodaux by early February. A third immature male Ruby-throated moved 91 miles from Lafayette in mid-November to Houma in early February.
Two Rufous also moved from one site to another within Louisiana. One, banded in late November in Covington, turned up 64 miles away in Thibodaux by late December. The other, caught in early December in eastern New Orleans, was found in Mandeville early in March. That distance is 23 miles.
A Buff-bellied that was banded in Harahan in mid-February remained on site until mid-March. It was caught just 5 days after departure in Houma, a distance of about 39 miles.
Remarkably, an immature female Calliope, banded in Reserve in early December was tallied on that Christmas Bird Count 21 December. Christmas eve she appeared at a feeder in Thibodaux, where she was recaptured a few days later. She promptly disappeared. However, on 18 January, she was again recaptured this time at the original site, where she remained for the rest of the season. The distance between these two sites is about 25 miles.
Some of these same-season re-encounters support the theory that not all hummers establish territories on their wintering grounds but rather drift about filching nectar from the territories of other hummers. This behavior is probably also practiced on their tropical wintering grounds where they must compete with native species, some of which are much larger than they are. Some of the other same-season re-encountered hummers are almost certainly true migrants, traveling a previously unstudied west-east/east-west route used by several species.
Returnees are the heart and soul of the project. These tenacious birds prove winter survival, indicate wintering site fidelity, and provide data concerning longevity. The oldest returnee this season was a female Rufous that was an adult when banded in January 1997. Thus, she would have hatched in the 1995 or earlier breeding season. She has returned to the same yard in Abita Springs every year since. Using the standard Bird Banding Laboratory method for calculating age, she is now at least 7 years 8 months old.
Another female Rufous returned to her winter home in Metairie for a fourth winter. She was an adult when banded in December 1998.
Another old-timer was a female Calliope that was already an adult when banded in February 2000. She returned to the same garden in St. Gabriel that she had resided in for the last 3 years.
7 other Rufous that returned to Louisiana chose different sites than previously. And, a Buff-bellied that spent 2 winters in Raceland opted for an Abbeville residence in 2002-2003.
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 a brief periods of freezing weather during late January. This episode 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 seemed to be available at all times.
The Louisiana Winter Hummingbird Project has benefited from the enthusiastic assistance and generous financial support 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 Frank Arthur, Mahlon Ayme, James Beck, Lynn Becnel, June Bernard, Laurie Binford, Franny Borello, Olga Clifton, Paul Conover, Dennis Demcheck, Kay Drouant, Bill Fontenot [Lafayette Nature Station], Kathy Klobucher, Satya Maliakal, Beth and Sammy Maniscalco, Rose and Jack Must [Wild Birds Unlimited, Lafayette], Glenn Ousset, John and Margaret Owens, Ron Stein, Melanie and Pat Stephens, Gene and Edna Street, Tom Sylvest, and Chris Witt for the many hours they have invested in this project. We appreciate their special help - and we are already looking forward to next season just 4 months away!
Nancy L Newfield
Metairie, LA USA