THIS WEEK at HILTON POND
8-14 March 2004
Installment #214--Visitor #unique visitor

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HERE COME THE RUBY-THROATS

After a long winter without Ruby-throated Hummingbirds, it's gratifying to know this diminutive Neotropical migrant is reportedly making its way back toward Hilton Pond Center and points north. It's hard to explain to folks who aren't hummingbird enthusiasts just how crucial this news is to those of us who brew batches of sugar water all summer long, but the annual arrival of spring migrant ruby-throats is one of the most-anticipated happenings in the world of backyard birdwatchers. Ruby-throats have already appeared along the Gulf Coast and are moving their way northward, so it's only a matter of time until phones start ringing and E-mails start flying as folks announce "I just got my first one at the feeder!" Since hummingbird watching is a such a highly competitive sport, few things are more important than being able to say you spotted the neighborhood's first ruby-throat of the season.

Click HERE for larger map
All text, maps & photos © Hilton Pond Center

At this time of year, as days lengthen and temperatures begin to warm, the most common inquiry we hear is "When should I put out my hummingbird feeders?" We have two responses to this eternal question. First, if you are a true hummingbird enthusiast in the eastern U.S., you maintained one feeder all winter long--just in case one of those vagrant hummers wandered in (see Winter Hummingbird Research). Granted, a winter feeder demands special care--bringing it in on freezing nights, swapping it at noon with a fresh, warm feeder on very cold days, or even rigging a heat lamp (left)--but the payoff is great in the eastern half of the country when you finally get an "out-of-range" Black-chinned, Calliope, or immature male Rufous Hummingbird (below right) hanging around to brighten winter days and keep you busy until the ruby-throats return.

If you did NOT have a winter hummingbird feeding program, we must respond to the query of when to put out the feeder in spring by simply saying it depends on where you live. Obviously, since migrant Ruby-throated Hummingbirds showed up in the southern parts of Texas and Florida as early as late February--a few even overwintered in coastal states--it is already well past the date to have your feeder up if you live in Miami or Corpus Christi. For Canada and most of the rest of the U.S., however, you still have time.

As far as ornithologists know, northward migration by Ruby-throated Hummingbirds in spring is tied to photoperiod on the birds' wintering grounds. Hummers in Mexico or Costa Rica don't watch the Weather Channel, so they have no idea what the temperatures are like in the Carolinas or Montreal in mid-March. Instead, when day-length reaches a certain level, an individual hummingbird's hormones kick in and bring about an urge to migrate. Hummers whose internal clocks run a little too fast migrate a little too soon, and they may arrive to find North America cloaked in snow (left) and devoid of nectar flowers and nutritious little insects. If they're slow to depart the tropics, they get to their breeding grounds to find earlier birds are already defending prime habitats, and latecomers during any given year may have to settle for not mating at all or, at best, raising weak offspring on insufficient resources.

Like other migrant birds, hummers are always "cheating" a little and trying to extend the limits by arriving earlier than their competitors, but those that cheat TOO much may end up freezing or starving to death during a particularly cold spring. Conversely, some late-arriving ruby-throats actually may get the last laugh on early birds if a sudden April snowstorm decimates hummers that arrived first. In nature, organisms are always caught between this kind of "rock and a hard place." It's such constant tension between hummingbirds and environmental factors that makes natural selection so dynamic a phenomenon--and one that's always fun to study.

But back to the question of when to put out your hummingbird feeder. Native Americans observed the sudden appearance of Ruby-throated Hummingbirds each spring long before Europeans settled North America, and they also saw the relationship between these long-billed little birds and tubular flowers upon which they naturally feed. In the past 50 years or so, folks have become quite active in offering artificial nectar as food, and in making observations about arrival dates of migrant ruby-throats. As a result, various groups and individuals--including our Operation RubyThroat: The Hummingbird Project--have been able to compile a map indicating when you might see the first spring ruby-throat at various latitudes and locations in the U.S. and Canada. Those dates are approximations--remember that the occasional hummer will try to cheat--but they give a pretty good idea of when to hang your feeder if you want neighborhood bragging rights for having the first hummingbird of the season, and maybe even your first nectar-bearing wildflowers, such as Red Columbine (above right).

If you check the map at the top of this page, you'll see the line labeled "April 1" passes along the border between the Carolinas. Hilton Pond Center sits just south of that border near York SC, so we would rightly conclude that our first Ruby-throated Hummingbird should appear on about April Fool's Day. In fact, our earliest-ever ruby-throat arrived on 27 March 1991--which is pretty darned close to 1 April--and over the past 20 years, 11 of our first arrivals at Hilton Pond Center have come on 3-6 April.

The bottom line from all this is that we advise folks in the Carolina Piedmont within a hundred miles or so of York to have their feeders up not later than St. Patrick's Day, 17 March. That may be a "wee bit" early, but putting out a feeder on the traditional Irish holiday makes it easier NOT to forget when to do it--and even if there are no hummingbirds in Ireland. For the rest of the country and Canada, we simply recommend that you hang a feeder--perhaps only one-fourth full--two weeks before the day indicated by the line on the arrival map.

It's worth noting that the lines on our map don't take into account local conditions such as altitude. In fact, almost no work has been done on whether Ruby-throated Hummingbirds arrive at different times on mountaintops than in adjoining valleys, or in natural areas vs. the suburbs. Likewise, we don't know much about the impact of microclimate on hummingbird migration, or how microclimate and altitude and other abiotic factors may affect breeding success or double brooding.

Those are the kinds of questions being looked at by students, teachers, and other adults in the U.S., and Canada who are involved in Operation RubyThroat through The GLOBE Program, and is why we went to Black Hawk County, Iowa a few weeks ago to train folks in our hummingbird protocols. Operation RubyThroat/GLOBE participants in Canada and the Midwest are looking at other aspects of hummer behavior, including whether Ruby-throated Hummingbirds are extending their breeding range past the pink line on the map at the top of the page. (Note also that migrant ruby-throats may be seen outside the breeding range.) They're also collecting data on when the last fall ruby-throats are seen across North America so we can construct a map that shows departure dates in fall migration.

If you reside in the Carolina Piedmont, it's high time to hang your hummingbird feeder, but if you live much north of Hilton Pond Center you have a little time left. In any case, have your binoculars ready and try to determine the sex of that first Ruby-throated Hummingbird that arrives--an easy call in spring when only males (below) have the bright red throat that gives this long-awaited migrant species its name.

All text, maps & photos © Hilton Pond Center

Satellite image courtesy motherplanet.com.
Approximate spring arrival dates and breeding range derived from Operation RubyThroat reports, personal experience, and various Web and print sources. Special thanks to "Hummingbirds of North America" by Sheri L. Williamson.

NOTE: Be sure to scroll down for an account of all birds banded or recaptured during the week, as well as some other interesting nature notes.


"This Week at Hilton Pond" is written and photographed by Bill Hilton Jr., executive director of Hilton Pond Center for Piedmont Natural History.

You may wish to consult our Index of all nature topics covered since February 2000. You can also use the on-line Search Engine at the bottom of this page.

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Oct 15 to Mar 15
Please report
your sightings of
Vagrant & Winter
Hummingbirds


Please report your
sightings of
Color-marked
Ruby-throated
Hummingbirds


BIRDS BANDED THIS WEEK
at HILTON POND CENTER

8-14 March 2004

SPECIES BANDED THIS WEEK:
Dark-eyed Junco--7
Chipping Sparrow--7

American Goldfinch--2
Northern Cardinal--2
Purple Finch--24
White-throated Sparrow--1
House Finch--1
Blue Jay--2
Mourning Dove--1

* = New species for 2004


WEEKLY BANDING TOTAL
9 species
47 individuals


YEARLY BANDING TOTAL
(2004)
14 species
1,102 individuals


BANDING GRAND TOTAL
(since 28 June 1982)
123 species
44,405 individuals


VAGRANT HUMMINGBIRDS
None this week.

All text & photos © Hilton Pond Center


This Week at Hilton Pond
is part of the

OTHER SIGHTINGS OF INTEREST
--After those unpredicted gale force winds in excess of 50 mph hit the Carolina Piedmont and Hilton Pond Center late on the evening on 7 Feb, we spent much of this week picking up fallen braches. Most were dead, and some of the larger ones had been hanging high in the trees after they were broken off during the devastating ice storm of November 2002. We're glad these "widow makers" are finally on the ground.


NOTABLE RECAPTURES THIS WEEK
(with original banding date, sex, and current age)

American Goldfinch (1)
12/12/02--after 2nd year female

Eastern Towhee (1)
10/20/01--4th year female

Northern Cardinal (3)
07/29/02--3rd year female
09/23/02--3rd year female
08/14/03--2nd year male

White-throated Sparrow (2)
11/06/00--5th year unknown
11/06/01--4th year female

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Hilton Pond Center for Piedmont Natural History is a non-profit research & education organization in York, South Carolina USA; phone (803) 684-5852. Directed by Bill Hilton Jr., aka The Piedmont Naturalist, it is the parent organization for Operation RubyThroat. Contents of this Web site--including articles and photos--may NOT be duplicated, modified, or used in any way except with the express written permission of Hilton Pond Center. All rights reserved worldwide. To obtain permission for use or for further assistance on accessing this Web site, contact the Webmaster.


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