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

RUBY-THROATED HUMMINGBIRDS
IN 2009:
SLOWEST START, FASTEST FINISH

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

Chart 2: Click on chart above to open a larger image in a new browser window

As shown on Chart 2 (above), since 1984 we have banded more than 200 Ruby-throated Hummingbirds just five times--all in the past six years. You'll also notice the red trend line shows a steady annual increase of new RTHU captures since we began 26 years ago. We don't think we've been getting particularly better at catching hummers--although we'll mention something about this year's techniques in a moment--so we might conclude the local population of Ruby-throated Hummingbirds is growing. That indeed might be the case, perhaps because Hilton Pond Center's changing habitats have become more attractive to hummers. When we purchased the property in 1982, the entire 11 acres was wide open with only a few mature trees. Now, through natural succession we have a mix of young woodland, shrubby areas, and small meadows that allow for greater diversity of flowering plants. Of these, our Trumpet Creeper thickets have matured mightily with many massive vines producing thousands of nectar-bearing blossoms each summer (below).

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

Trumpet Creeper, Campsis radicans, is a true "hummer magnet" and is possibly the single most important native hummingbird flower across the eastern U.S. It stands to reason lots of Trumpet Creeper blooming at the Center May through September may have brought in and sustained increasing numbers of ruby-throats through the years--particularly now that the property also offers lots of nesting sites and shelter in a variety of trees and shrubs.

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

Most years we catch the majority of our Ruby-throated Hummingbirds in any of several kinds of traps in which the door is activated via pull-string or electronic remote. As we work at our computer desk or dine at kitchen table, we always have one eye on the computer screen or dinner plate and the other on traps just outside the window. If a hummer enters to drink some sugar water, we pull the string or hit the button and capture the hungry bird. Most days April through October we also run a half dozen 30mm mist nets dawn to dusk around the Center's old farmhouse and check them every quarter-hour to see if any hummingbirds have gotten caught. Historically we caught 75% or more of our RTHU in traps activated by the bander; the remaining 25% got snared in nets. This year, however, we introduced a different trapping procedure that may have had major impact on results.

All text, charts, tables & photos © Hilton Pond Center
Photo of Ross Dawkins trap (above) courtesy Brent Ortego

In late July we learned about a new style of hummingbird trap developed by Ross Dawkins of San Angelo TX. Ross covered two metal hoops with half-inch plastic netting and connected them with a cylinder made of similar mesh. Ross hung a hummingbird feeder inside After cutting a 4" x 4" opening in the lower cylinder wall; there are no moving parts but a hungry hummer can get at the feeder through the opening. Rather than backing out of the trap via the relatively small hole through which it entered, a typical hummingbird flies upwards and becomes disoriented temporarily--just as it might after flying through an open garage door. Most hummers take a while to find their way down and out of the Dawkins trap, so it's simply a matter of keeping an eye on the apparatus and extricating any hummingbird inside before it escapes on its own. Following instructions and a photo (above) sent by master hummingbird bander Brent Ortego, one of Ross's colleagues who tried the set-up, we decided to give the Dawkins trap a try and spent several hours in mid-August making our first two.

We deployed our new Dawkins devices on 24 August and that day caught eight ruby-throats--one in a mist net, one in a pull-string trap, and six in the Dawkins traps. After this preliminary success we manufactured and put out two more traps designed by Ross and saw an amazing increase in hummers captured for banding. From 24 August until season's end we caught 156 Ruby-throated Hummingbirds--just 28 in mist nets and 23 in pull-string or electric traps, but a whopping 105 in Dawkins traps. Although part of the increase was due to the usual August irruption of ruby-throats, we're convinced many Dawkins trap captures would have passed through Hilton Pond Center without ever being banded; we suspect these hummers would have avoided nets and/or would not have been observed in a bander-operated trap when we could trigger the trapdoor. We can't wait to see what happens NEXT year when we have Dawkins traps deployed as the first ruby-throats beginning returning from the Neotropics.

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

Banding hummingbirds allows us to collect information about these tiny birds that is simply unavailable otherwise. In addition to learning specifics about where ruby-throats migrate to and from, we find out about site fidelity and longevity--two things one cannot deduce unless individuals are captured, banded, and then encountered again at a later date. Conveniently, using plumage characters we can also tell with 100% accuracy the sex of a Ruby-throated Hummingbird in the hand, and at Hilton Pond Center can determine conclusively whether a bird is immature or adult. (Notice the incomplete red gorget and dark throat streaking on the immature male, above.) Knowing the age make-up of a RTHU population is of importance; if one autumn we band lots of immatures we might conclude nesting attempts were successful, but if another year yields mostly adults and very few immatures it might indicate breeding collapse--perhaps due to a late spring freeze, stormy summer weather, or some other external factor such as an environmental pollutant that might disproportionately affect young hummers. In any case, knowing one year's age ratios are "off" might lead us to look for the proximal cause and, if possible, take action to bring things back into balance.

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

We have no speculation on recent causative factors, but in 2009 the number of adult birds banded was low while immatures of both sexes were well above average (see Table 1 above). Adult females were particularly scarce; they usually outnumber adult males by about a 3:2 ratio at Hilton Pond Center. (Immature males outnumber young females by that same margin.) Interestingly, we set a new high with 71 immature females and came within sight of the record for young males. The low numbers of adults is related, in part, to our catching NO new birds March through May when adults would have been the only ruby-throats available. Still, we should have caught more than just 16 adult hummers in June and July after this year's broods began fledging.

Among other things of interest about Ruby-throated Hummingbirds returning to Hilton Pond Center in 2009:

• Of the 16 returns (Table 2), nine had been banded as adult females in a previous year, while just one was an adult male. As shown in Table 3, banded adult females are much more likely than any age/sex class to return in a later year.
• A fourth (n = 4) of our returns were banded as young, hatch-year males. This was a relatively high number of hatch year males that, as shown in Table 3, typically return at a MUCH lower rate.
• Estimates are that 70-80% of all RTHU die before reaching their second year, so our overall 11.7% return rate is pretty good.

Adult male Ruby-throated Hummingbird (above) with full red gorget and faded green color mark on upper breast

As usual for our end-of season hummingbird report we've shown you a bunch of numbers. That's about the only way to summarize our annual hummer banding results, so we hope the analysis has been of interest and you can relate it to Ruby-throated Hummingbirds you observed this year in your own backyard. If nothing else it can be food for thought through the cold winter months as we all wait to see whether next year's hummers have another slow start and fast finish at Hilton Pond Center.