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15-21 July 2005
Installment #278---Visitor #

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Winter Hummingbird Expedition to Costa Rica
in November/December 2005 or February 2006

Informative and entertaining hummingbird banding presentations are coming up in August 2005 in South Carolina, Virginia, Maryland & Kentucky/Tennessee.
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If you've ever been to the tropics, a favorite attraction at many lodges is a series of wires and walkways that meander through the tree canopy. For folks who aren't acrophobic, a canopy tour is thrilling for many reasons. It's a rush to be a hundred feet in the air, of course, but from a scientific standpoint it's a terrific way to see tree-top organisms we seldom encounter at ground level. We always thought it would be neat to have an observation deck high in our tallest oak trees at Hilton Pond Center, if only to see what kinds of birds and insects might be flitting about in top-most branches. We've never had opportunity to construct such an aerial platform, so we have to content ourselves with enticing canopy dwellers to come down to us. One way is to set up an ultraviolet "black light" against a white bedsheet near the base of a tree, in the hope some insects will be attracted to a "fake moon." Such was the case this week when an incredible beetle came down from its normal habitat and landed on the sheet long enough for us to scrape it gently into a jar--all the better to examine and photograph our newly found "long-horned" insect.

All text & photos © Hilton Pond Center

We knew at first glance our six-legged capture was indeed a member of the Long-horned Beetle Family (Cerambycidae), shown about four times life-size in the photo above. To be honest, calling this little insect's antennae "long" is an understatement; the beetle itself was only about three-quarters of an inch in length, but each extended, tapering antenna was twice as long as its body. Longhorn, indeed!

There are reportedly more species of beetles than any other insect order--some sources claim a quarter of all named animal species are in the Beetle Order (Coleoptera)--so it's not always easy to identify beetles in-hand. We were fortunate at least to be able to narrow our new beetle to the long-horn family level, but there are nearly 300 genera and 1,200 species of cerambycids--and that's just in North America. A variety of characters--especially a barrel-shaped pronotum (i.e., the exoskeleton over the thorax, or middle body section)--put our catch into the Cerambycinae, or Round-necked Long-horns. Members of this subfamily--of which there are about 450 North American species--are primarily tree-dwellers; they're also tree-EATERS, especially in the larval stage.

Not being coleopterists or having a good beetle key to follow, our attempt to identify the beetle to species followed a time-honored procedure of comparing it to photos in whatever insect field guides we had on-hand. Because we couldn't find an acceptable match, we posted an inquiry on an insect listserv and learned from beetle field guide author Dr. Doug Yanega of University of California-Riverside our beetle was a Spined Oak Borer, Elaphidion mucronatum--whose common name comes in part from the spiny projections on several antenna segments (above right) and its "knees" (femoral leg segments).

Spined Oak Borers occur from New York to Michigan and south to Florida. The adult has massive pinching mandibles (above) that apparently are used to work on dead branches of various hardwood trees, including towering oaks. We've been unable to learn whether the adult beetle actually eats the wood, or if this important decompositional work is performed only by its larvae--hence the name "Spined Oak BORER." This species lays its eggs under bark scales on dead tree limbs, after which the larvae spend their first year feeding just under the bark; during the second year, the larve migrate deeper into the dead wood, pupate, and eventually emerge as adults.

One thing we HAVE surmised is that the specimen pictured herein is likely a male, which we deduced by its extremely long antennae. Although such extended sensory structures might be a secondary sex characteristic that helps attract females, we suspect instead that longer antennae sense odor and help males do a better job of finding prospective mates when the females exude chemical pheromones.

As always, we welcome additional knowledge our readers may have about our weekly topic and will update this installment if any new tidbits about the Spined Oak Borer are forthcoming. In the meantime, instead of going into the treetops to meet more beetles where they live, we'll just continue nighttime operation of our ground-level ultraviolet light trap. This should entice additional insects down from the tall oaks at Hilton Pond Center, and we suspect we'll find even more species of long-horned beetles clinging to the bedsheet.

All text & photos © Hilton Pond Center

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

"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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Please report your
sightings of
Ruby-throated Hummingbirds


15-21 July 2005

Ruby-throated Hummingbird--13
House Finch--3
Mourning Dove--1

* = New species for 2005

3 species
17 individuals

44 species
908 individuals

(since 28 June 1982)
124 species
46,215 individuals

This Week at Hilton Pond
is part of the

(with original banding date, sex, and current age)
Ruby-throated Hummingbird (5)
07/15/01--after 5th year female *
07/23/03--after 3rd year female
08/14/03--3rd year female
07/16/04--after 2nd year female
08/22/04--2nd year male

* This old female RTHU, banded as an adult in 2001, was not encountered at Hilton Pond Center in 2002 but has returned each year since.

--Although many female Ruby-throated Hummingbirds (RTHUs) we band at Hilton Pond Center have throats that are spotless white, some show very light gray throat streaking. Young (first-year) males can also have white throats, but they typically have at least some degree of black or dark green streaking that eventually is replaced by a full red gorget (see RTHU External Appearance). Very rarely do we capture an older female with a single black fan-shaped throat feather, but that was the case this week for TWO females--one after-fifth-year and the other after-third-year (see photo of the latter bird at left).

All text & photos © Hilton Pond Center

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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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