22-28 February 2010
Installment #465---Visitor #blogger statistics

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When people ponder pollination, they usually think about Honey Bees--those ubiquitous social insects that collect nectar, spread pollen, and make delectable sweet liquid that gives them their name. Indeed, Honey Bees have become critically important as pollinators for a multitude of native plants and agricultural crops. Most folks don't realize Honey Bees, Apis mellifera, aren't even native to the Western Hemisphere but were brought over by early settlers to provide honey. In centuries since, our native North American pollinators--including birds and bats, flies and beetles, wasps and bees, and butterflies and moths, among others--have been in decline due in part to pesticide abuse. One animal that seems to be doing well, however, is the Ruby-throated Hummingbird, a species oft-forgotten when the topic of pollination comes up.

All text & photos © Hilton Pond Center

Without pollinators, nature AND humans would be in big trouble. Except for the relatively few self-fertilizing plants or those that are wind-pollinated, vast numbers of flora depend on animal agents to carry pollen from one flower to the next. And many of those plants produce foodstuffs consumed by humans; in fact, as the North American Pollinator Protection Campaign (NAPPC) likes to point out, one of every three bites of food you ate today came through the work of pollinators. To our knowledge Ruby-throated Hummingbirds (RTHU) don't pollinate any crops of agricultural importance, but they apparently do serve as pollinators for numerous herbaceous and woody plants. In the eastern U.S. and southern Canada where RTHU breed, they're closely associated with a variety of spring-, summer-, and autumn-blooming plants such as those shown in the grouping below.

Red Buckeye

Red Columbine

Spotted Jewelweed

Canada Lily


Cardinal Flower

Trumpet Honeysuckle

All text & photos © Hilton Pond Center

Even a cursory look at the seven flowers above reveals all are more or less tubular--exactly what you might expect from a plant adapted to borrowing the hummingbird's long, tapered bill as a tool for pollination. Not coincidentally, all blossoms are also some shade of red--a color that stands out sharply against green vegetation that predominates the natural landscape; it's not that hummers are particularly attracted to red, it's just that they can find red flowers more easily, and many of those red flowers are nectar-rich.

All text & photos © Hilton Pond Center

Added to the above group is an eighth plant we believe to be single most important native hummingbird flower in eastern North America--Trumpet Creeper, Campsis radicans (photos just above, below right, and at top of page). This four-inch tubular red-orange blossom carries a heavy nectar load and grows almost everywhere Ruby-throated Hummingbirds breed in the eastern U.S. Trumpet Creeper begins blooming in late spring just when young RTHU hatch, and the flowers continue until early September when fledgling and adult ruby-throats start heading south for the winter. This finely tuned bird/flower relationship is an undeniable example of co-adaptation.

All text & photos © Hilton Pond Center

As we have observed during our ten expeditions to Costa Rica, the Trumpet Creeper vine--a member of the Catalpa Family (Bignoniaceae)--has several relatives in the Neotropics that also bear tubular flowers, but they're anything but bright red in color. One (above) is close with purplish-pink blossoms, while the other (below) is a very different, very deep yellow.

All text & photos © Hilton Pond Center

Despite not being red, these two tropical members of the Bignoniaceae make copious nectar and we've observed Ruby-throated Hummingbirds visiting both on the hummers' wintering grounds in Guanacaste Province on Costa Rica's Pacific coast. (NOTE: If you know the species names for these two vines or any other flowers not identified on this page, please send the info to RESEARCH.)

Wild Petunia

Papaya (male flower)

Turk's Cap



Blue Vervain (Porterweed)



Aloe Vera

All text & photos © Hilton Pond Center

Several other Costa Rican flowers at which we've observed ruby-throats nectaring are grouped above. Some such as Lantana and Turk's Cap are red or reddish and even tubular, but others like Inga and Pochote are white and feathery. And then there's the yellow, tubular, non-native Aloe Vera (just above) that was imported from Africa and turns out to be a true hummingbird magnet in Guanacaste. So what's going on here? Why in the Neotropics don't we see Ruby-throated Hummingbirds primarily visiting red, tube-shaped flowers as they do on the breeding grounds in North America?

All text & photos © Hilton Pond Center

It's not that there aren't any tubular red flowers in Costa Rica; in fact, there are plenty. These include several species of Erythrina, for example, but the one pictured above is mostly inaccessible to Ruby-throated Hummingbirds because its three-inch recurved corolla is too long and narrow for their bills.

All text & photos © Hilton Pond Center

This long-flowered red Erythrina is visited instead by the Plain-capped Starthroat (above), whose head is about the same size as that of a male ruby-throat (below) but whose two-inch bill is more than twice the length of a ruby-throat's. The starthroat needs to stick out its tongue less than an inch to reach nectar at the end of the Erythrina tube--a feat the RTHU cannot duplicate.

All text & photos © Hilton Pond Center

Instead of wasting time on fruitless efforts to probe blossoms of Erythrina--especially when the larger, better-adapted Plain-capped Starthroat defends the tree and chases them away--Ruby-throated Hummingbirds seek out flowers with nectar that can be lapped more easily. Some floral sources are neither red nor tubular.

All text & photos © Hilton Pond Center

One non-native tree that ruby-throats flock to in Guanacaste in mid-February is Gmelina arborea (above), imported from India and planted as a timber source in Central America. During its three-week dry season bloom period, each mature tree produces tens of thousands of two-inch flowers containing nectar attractive to orioles and hummingbirds alike. Granted, these blossoms are purplish-yellow (i.e., almost red-like), but it would be a stretch to call them tubular.

All text & photos © Hilton Pond Center

Another tree--this time a native--frequented by Ruby-throated Hummingbirds during our 2010 expedition to Costa Rica was Madero Negro, Gliricidia sepium (above). Giant members of the Pea Family (Fabaceae, AKA Leguminosae), Madero Negro trees towered over Aloe Vera fields at the former Carrington plant south of Liberia and drew in quite a few ruby-throats, including the female above.

All text & photos © Hilton Pond Center

Madero Negro flowers occur in dense clusters (above and below) at the ends of branches during February, about halfway through Guanacaste's dry season. We observed at least three hummingbird species visiting Madero Negro, with Ruby-throated Hummingbirds frequently showing territoriality in defending a tree and its blossoms against their own conspecifics.

All text & photos © Hilton Pond Center

This is all of interest, but we still haven't answered the question of how it is the red-tubular-flower-ruby-throated-hummingbird relationship prevalent within this bird's North American breeding range doesn't seem to be replicated on RTHU wintering grounds in Costa Rica. We speculate it may be heavy competition from at least some of the ten other non-migratory hummingbird species on our Guanacaste study sites that drives wintering ruby-throats to be much more opportunistic and generalistic in their feeding habits.

Although RTHU probably did evolve with red tubular flowers as their primary carbohydrate sources in eastern North America, "up here" they also feed from other blossoms during the breeding season. Hummingbirds are innately curious, and if a ruby-throat sticks its bill into a flower of any shape or color and gets a nectar reward, chances are it will continue to visit similar sources. That's why such non-natives as sages (Salvia spp.) with blue flowers and Rose-of-Sharon (above) with its big, flat, white inflorescence attract RTHU in droves when such blossoms are available. (And why else would a hummer go repeatedly to a glass and plastic feeder unless it got a sugar fix each time?)

Although there's little question Ruby-throated Hummingbirds are North American pollinators of tubular flowers such as Trumpet Creeper, whether they serve in transferring pollen for flora in the Neotropics is another question. It may be that for some flowers RTHU--present in Costa Rica for half the year--play a pollination role equal to or even greater than non-migrant resident hummers; after all, many plants in western Costa Rica bloom only during the dry season when ruby-throats are present and--based on our six winters of observations--may actually be the most common Guanacaste hummingbird species January through February.

The relative importance of migratory Ruby-throated Hummingbirds as pollinators of native Neotropical plants is a subject that's wide-open for investigation by our Operation RubyThroat teams on future expeditions. Care to join us in 2011 in Costa Rica--or Nicaragua or Guatemala or Belize--to further investigate this vital ecological concept?

All text photos © Hilton Pond Center


Flowers below were first observed in 2009 or 2010 being visited by RTHU in Costa Rica. For an earlier discussion of plants at which we have seen RTHU nectaring during our other Neotropical hummingbird expeditions, please see
Costa Rica Hummingbirds 2008: Beyond The Aloe Vera

(NOTE: If you know the species names for any plants not
identified on this page, please send species info to RESEARCH.)

All text photos © Hilton Pond Center

All text & photos © Hilton Pond Center

Ruby-throated hummingbirds feed on nectar from Yellow Poui, Tabebuia ochracea (above), yet another tropical member of the Bignoniaceae--a family that includes North American natives Trumpet Creeper, Southern Catalpa, and Crossvine.

All text & photos © Hilton Pond Center

These red tubular flowers (above) visited by ruby-throats were growing on the perimeter of one of our Aloe Vera study sites at Cañas Dulces. They are similar to Turk's Cap (a hibiscus) but we're not sure of their identity.

All text, maps, charts & photos © Hilton Pond Center

Some ruby-throats were feeding on spidery white flowers (above) of a small tree new to our ever-growing list of Costa Rican plants from which we've seen ruby-throats taking nectar. We believe the tree to be a species of Bauhinia.

All text, maps, charts & photos © Hilton Pond Center

Still more red, tubular blossoms (above) visited by ruby-throats were identified by Costa Rica trip participant Ken Wood as Wild Firecracker, Russellia sarmentosa. Botanists disagree whether it is in the Scrophulariaceae or the Plantaginaceae.

All text & photos © Hilton Pond Center

Last year we added Kapok, Ceiba pentandra, to the list of RTHU nectar sources. Flowers of this tree (above) open in the morning but lose their petals by lunchtime.

All text photos © Hilton Pond Center

This unidentified white flower (above) and accompanying leaves were beaten badly by the winds that hit Guanacaste Province during early February 2009. Produced by a shrub or small tree, the flower is one of many upon which we observed Ruby-throated Hummingbirds feeding.

All text photos © Hilton Pond Center

Another unidentified nectar source visited occasionally by Ruby-throated Hummingbirds was a white flower (above) produced by a ground-hugging vine growing among the Aloe Vera. The flower structure is reminiscent of hibiscus.

All text photos © Hilton Pond Center

For complete reports on all our successful Costa Rican hummingbird banding expeditions, please visit
"This Week at
Hilton Pond" at the following links:
22-28 Feb
(5-year Summary)


Week 1: COSTA RICA (29 Jan-6 Feb)
Week 2: NICARAGUA (9-17 Feb)
Week3: GUATEMALA (20-28 Feb)
Week 4: BELIZE (3-11 March)

Multi-trip discounts available as we move northward in Central America, following Ruby-throated Hummingbirds as they head
out on spring migration. Click on the countries above for maps, day-by-day itineraries, and information about joining us in
Central America in 2011.

A summary of our successful 2010 Costa Rica expedition is at
The 20-Tenners In Costa Rica.

The write-up about our first-ever Belize excursion is at
Belize-Oneers At Crooked Tree: Another Successful
Hummingbird Expedition (2010)

Comments or questions about this week's installment?
Please send an E-mail message to INFO.

Be sure to scroll down for an account of all
birds banded or recaptured during the period,
plus other nature notes of interest.

Thanks to the following fine folks for recent gifts in support of Hilton Pond Center for Piedmont Natural History and/or Operation RubyThroat: The Hummingbird Project. Your tax-deductible contributions allow us to continue writing, photographing, and sharing "This Week at Hilton Pond." (Please see Support if you'd like to make a gift of your own. You can also contribute by ordering an Operation RubyThroat T-shirt.)

  • Holbrook Travel, especially Debbie Sturdivant
  • The six members of the 20-Tenners who underwrote, in large part, our 2010 hummingbird expedition to Guanacaste Province, Costa Rica: Pat Barker, Abigail Cooke, Anne Fuller, Brenda Piper, Ken Wood & Levi Wood.
  • Ernie & Linda Carman of Finca Cristina, producers of organic shade-grown coffee
  • Elaida "Ela" Villanueva Mayorga for her diligent volunteer work extracting hummingbirds from mist nets during our 2010 field studies

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

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22-28 February 2010

American Goldfinch--15
Song Sparrow--1
Purple Finch--22
House Finch--4

* = New species for 2010

4 species
42 individuals

10 species (29-yr avg = 66.8)
200 individuals (29-yr avg = 1,857)

(since 28 June 1982, during which time 170 species have been observed on or over the property)
124 species
53,842 individuals

(with original banding date, sex, and current age)

American Goldfinch (2)
09/17/07--5th year female
01/15/09--3rd year male

Pine Warbler (1)
02/28/09--after 2nd year unknown

House Finch (2)
08/13/09--2nd year male
08/16/09--2nd year male

This Week at Hilton Pond
is part of the

Nature Blog Network

All text & photos © Hilton Pond Center

--Much of our week was spent traveling to and from Topeka, Kansas, to deliver a eulogy for Unka Dennis, patriarch of the Dressler Clan who passed away on 20 Feb at age 86. A WWII veteran, building contractor, MerleFest devotee, tinkerer, and card-carrying member of the Flat Earth Society, Elbert Dennis Dressler of Lebo KS will be remembered fondly as he who who would argue with anyone about anything from any perspective, and for his two greatest inventions: The Collapsible Go-Cart and the Amphibious Motor Home. We will miss the twinkle in his eye and his good-natured chuckle and will think of him every time we eat a Hershey's milk chocolate Nugget with almonds. (Fear not, Unka Dennis, the addiction lives on!)

Operation RubyThroat has teamed with EarthTrek so citizen scientists--like YOU--can contribute observations about hummingbird migration and nesting behavior. Membership is free for this great new opportunity to help increase scientific understanding of Ruby-throated Hummingbirds. On-line data entry forms are now live, so please register today at EarthTrek.

NOW is the time to begin reporting your RTHU spring arrival dates for the U.S. & Canada, and spring departure dates for Mexico & Central America. Please participate.

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

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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 all 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.