THIS WEEK at HILTON POND
22-31 October 2008

Installment #417---
Visitor #home page tracking

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Blue-throated
Goldentail
(male)

Weeks One is full and Week Three has only one slot remaining for our annual
Hummingbird Expeditions to Costa Rica
.
Week Two
(3-11 Feb 2009)
is filling fast.

Canivet's
Emerald
(male)


RUBY-THROATS OF 2008:
WHERE DID THEY (FINALLY)
COME FROM?

We give up on Ruby-throated Hummingbirds at Hilton Pond Center. No, we're not going to quit feeding, observing, and banding them, but we're about ready to say we will never again make a prediction about how many we'll capture by the end of a given banding season. Why this hesitation? Mostly because 2008 started out as one of our slowest springs ever for banding ruby-throats at the Center and things got even worse, with only SEVEN hummers banded through 30 June. We were almost despondent over this obvious lack of Ruby-throated Hummingbirds and predicted 2008 would end as one of our worst years--a prediction supported by folks from across the Southeast who also reported unusually low numbers of ruby-throats. Eventually, hummingbirds--as they usually do--began to appear during the first week in July but continued showing up at only an average pace until late August. Then the population exploded and we could hardly keep up with all the hummers in our nets and traps. In the end, 2008 turned out to be our BEST year ever, not our worst. So where did all these late summer and early autumn birds (finally) come from?

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

Chart 1: Click on chart above to open a larger image in a new browser window

The season started with the arrival of an unbanded adult male on 9 April 2008 (see red line on Chart 1 above), almost two weeks after our early banding record of 27 March 1991; most years we band our first Ruby-throated Hummingbird (RTHU) at Hilton Pond Center on or before 10 April--which happened to be the date of our second banding in 2008. After that progress was excruciatingly slow with NO new birds at all in May and only one returning bird on 30 May. The next new RTHU was on 2 June, and we ended up with only five new birds for that entire month. As Chart 1 shows, things finally began improving in early July, with a substantial number of new birds appearing in mid-September. The final capture occurred on 9 October, a little later than our average late date for the last RTHU of the season--but earlier than our record of 18 October set 'way back in 1986.

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

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

The spaghetti-like lines on Chart 1 depict how banding progressed through the 2008 hummingbird season, but it's easier to see how successful we were this year by looking at the bar graph in Chart 2 just above. As shown, our previous best year was three years ago (2005) when we banded 226 RTHU. For some reason there was a big drop in 2006 with only 164 hummers captured, but the Hilton Pond population--which includes both breeding birds and spring and fall migrants--rebounded nicely in 2007 to our fourth-best total of 204 birds. This year trumped them all, with 230 RTHU banded--well above our 19-year average of 173.4. (NOTE: This figure does not include six partial field seasons for which we were away from Hilton Pond for significant portions of the summer.)

If we can trust the red trend line on Chart 2 above, Ruby-throated Hummingbirds appear to be on the increase at Hilton Pond Center. We doubt the upward curve is a result of our becoming more experienced at catching hummers, nor does it reflect more hours of trapping and mist netting.

Table 1: RUBY-THROATED HUMMINGBIRDS
BANDED AT
HILTON POND IN 2008, COMPARED TO ALL-TIME HIGHS AND
19-YEAR AVERAGES
Adult
Males
Adult
Females
Hatch- Year
Males
Hatch- Year
Females
TOTAL
2008
Totals
20
39
118 *
53
230 **
2007
Totals
21
47
71
65
204
Record
High
34
47
118
68
230
19-year
Average
21
30
73
49
173
* Previous record for juvenile males was 108, set in 2005.
** Previous Record for annual total was 226, set in 2005.

Note: We have been banding RTHU at Hilton Pond Center since 1984--a 24-year span--but for six of those years we were away for substantial periods during the summer; we do not include those years when calculating averages.

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

As each hummingbird banding season ends, it's always interesting to look at the breakdown among age/sex classes as illustrated in Table 1 (above). Most years adult females outnumber adult males by about a 3:2 margin, while the ratio flips among young birds so that fledgling males outnumber young females. Adults varied from this trend in 2008, primarily because we banded an above-average number of adult females (39) while capturing a below-average number of adult males (20), giving a 2:1 ratio. Among juvenile RTHU, males were much more plentiful than usual (70% compared to the 19-year average of 60%), mostly because our 118 hatch-year males banded blew the previous record by ten individuals--and even though our 53 young females in 2008 were above average. Had all age classes been banded at the same rate as young males, we might have approached 300 RTHU for the year at Hilton Pond Center.

Along with setting a record high with 230 new Ruby-throated Hummingbirds banded in 2008 at Hilton Pond, we also did quite well on returning birds from previous years. On average we have about 26 "old" birds coming back; in 2008 we tallied 38 of them--second only to the whopping 49 we had in 2007. Those 38 individuals returning this year are listed in Table 2 below, showing the banding date and when each was recaptured in 2008, as well as its age at banding and recapture and any previous returns. (We won't apologize that the list is long; in fact, we're excited it is!)

Table 2: 38 BANDED RUBY-THROATED HUMMINGBIRDS
RETURNING TO
HILTON POND IN 2008
(HY = hatch year bird, which becomes SY or 2nd year on 1 Jan. An adult bird whose hatching year is not known is called AHY, or "after hatch year"; on 1 Jan an AHY bird becomes ASY or "after 2nd year," and so on.)
Band
#
Recapture
Date
(2008)
Banding
Date
Age/Sex
at
Banding
Age
at
Recapture
Years of
Previous
Returns
Y16128
5/30
8/13/07
AHY-F
after 2nd year
-
Y16055
6/2
5/29/07
AHY-M
after 2nd year
-
Y16136
6/2
8/14/07
AHY-F
after 2nd year
-
Y15877
6/2
6/6/06
AHY-F
after 3rd year
07
Y16045
6/3
5/26/07
AHY-F
after 2nd year
-
Y16124
6/5
8/9/07
HY-F
2nd year
-
Y16053
6/11
5/28/07
AHY-F
after 2nd year
-
Y16032
6/16
4/16/07
AHY-M
after 2nd year
-
Y16066
7/1
6/15/07
AHY-F
after 2nd year
-
Y15972
7/7
8/31/06
HY-F
3rd year
07
Y16115
7/7
8/6/07
HY-M
2nd year
-
Y16086
7/7
7/19/07
AHY-F
after 2nd year
-
Y16112
7/7
7/30/07
AHY-F
after 2nd year
-
Y16043
7/8
5/25/07
AHY-F
after 2nd year
-
Y15725
7/13
8/17/05
HY-F
4th year
06,07
Y15873
7/13
6/1/06
AHY-F
after 3rd year
-
Y15939
7/13
8/17/06
AHY-F
after 3rd year
07
Y16062
7/14
6/7/07
AHY-F
after 2nd year
-
Y15682
7/14
7/26/05
HY-F
4th year
06,07
Y16156
7/14
8/23/07
HY-F
2nd year
-
Y16094
7/14
7/21/07
HY-M
2nd year
-
Y15669
7/14
7/16/05
AHY-F
after 4th year
07
Y16100
7/14
7/23/07
AHY-F
after 2nd year
-
Y16137
7/16
8/15/07
AHY-F
after 2nd year
-
Y15983
7/16
9/6/06
HY-M
3rd year
07
Y16059
7/17
5/30/07
AHY-F
after 2nd year
-
Y15925
7/18
8/8/06
AHY-M
after 3rd year
07
Y16087
7/18
7/11/07
AHY-F
after 2nd year
-
Y16126
7/19
8/12/07
HY-M
2nd year
-
Y16117
7/24
8/6/07
HY-M
2nd year
-
Y16064
7/30
6/9/07
AHY-F
after 2nd year
-
Y16171
7/30
8/27/07
HY-F
2nd year
-
Y16088
7/30
6/9/07
AHY-F
after 2nd year
-
Y16141
7/31
8/16/07
HY-M
2nd year
-
Y16074
8/12
7/3/07
HY-M
2nd year
-
Y16200
8/15
9/8/07
HY-F
2nd year
-
Y16069
8/16
6/30/07
HY-F
2nd year
-
Y15652
8/17
6/8/05
AHY-F
after 4th
none!

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

Banding Ruby-throated Hummingbirds provides interesting data, but RECAPTURING them tells us much more--even if the birds aren't encountered long distances away from the banding site. Thus, we'd like to point out a few things in Table 2 (above) that should be of interest to the hummingbird enthusiast, especially when we include additional results from Table 3 (below).

Table 3: RETURNS OF RUBY-THROATED HUMMINGBIRDS BANDED at HILTON POND,
1985-2008
(Does not include birds banded in 2008
that won't have their first return until next year)
AGE/SEX
Total
Returns
Total
Banded
Percent
Returns
Adult Males
55
446
12.3%
Adult Females
134
640
20.9%
Hatch-year Males
110
1,509
7.3%
Hatch-year Females
141
1,019
13.8%
All Age/Sex Classes
440
3,614
12.2%

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

Among other things of interest about Ruby-throated Hummingbirds returning to Hilton Pond Center in 2008:

  • Of the 38 returns (Table 2), 20 had been banded as adult females in a previous year, while just three were adult males. As shown in Table 3, banded adult females are much more likely to return in a later year.
  • Eight of our returns were banded as young, hatch-year females, while seven were young males. This was a surprisingly high number of hatch year males that, as shown in Table 3, typically return at a MUCH lower rate than any other age/sex class
  • We were quite disappointed in 2008 not to see any of our three "Methuselah birds" from last year, i.e., two RTHU that were sixth-year birds and one that was an incredible after-sixth-year. Our oldest birds in 2008 were nonetheless beyond middle age for a ruby-throat: Two after-fourth-year females that had to have hatched prior to 2005. (Estimates are that 70-80% of all RTHU die before reaching their second year, so our overall 12.2% return rate is pretty good.)
  • One of 2008's after-fourth-year females was banded in June 2005 and not seen again until this year, while the other one skipped 2006.

As usual for our end-of season hummingbird report, we've shown you a bunch of numbers. That's about the only way we know to present information summarizing our annual hummer banding results, so we'll end up with the photo below of an adult male Ruby-throated Hummingbird that hung around until mid-October before departing for the Neotropics.

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

This bird was color-marked with temporary green dye on its breast--a sure sign it was banded at Hilton Pond Center. We color mark so we don't pull the string and re-trap the same hummers over and over again, but we band so we can better understand migration, longevity, and site fidelity. However, neither our banding scheme or our color marking strategy completely answer that question we asked at the beginning of this essay: After such a slow start in 2008, where did all these late summer and early autumn hummers (finally) come from? Although we suspect few were locally produced, the question will go unanswered. This is because we've never caught a Ruby-throated Hummingbird banded elsewhere by someone else--and we're not REALLY giving up on Hilton Pond hummingbirds until we do.


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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.


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"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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BIRDS BANDED THIS WEEK at
HILTON POND CENTER

22-31 October 2008

SPECIES BANDED THIS WEEK:
House Finch--9

* = New species for 2008


WEEKLY BANDING TOTAL
1 species
9 individuals

YEARLY BANDING TOTAL (2008)
64 species
1,642 individuals

27-YEAR BANDING GRAND TOTAL
(since 28 June 1982)
124 species
51,809 individuals

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

None this week

All text & photos © Hilton Pond Center

OTHER NATURE NOTES OF INTEREST
--If we thought last week's totals were low (eight birds banded from seven species), this week at Hilton Pond Center we were reduced to trapping just nine House Finches. (We also had no recaptures.) In part this happened because rain, wind, and road trips prevented us from running mist nets, but we actually see precious ew birds as we gain out our office window. We suspect numbers will improve as temepratures drop, wild foods become increasingly scarce, and winter residents move in from up north. As always, our goal is to band at least 2,000 birds in 2008, but that's looking a little iffy.


This Week at Hilton Pond
is part of the

PERSONAL NOTE

Our dear and lifelong friend, Haywood Daniel McCallum Jr., was shot several times and wounded severely by robbers outside his home in Richmond VA on the evening of 11 October 2008. We have known kind-hearted Woody, a gifted and widely admired music teacher retired from Richmond schools, for almost 40 years--ever since 1969 when we were on "staph" and he was a delegate to West Virginia's prestigious National Youth Science Camp.

Thanks to community support, police have arrested one of two suspects. Woody is still battling for his life at Virginia Commonwealth University medical center and has been through numerous surgeries and procedures. As much as it pains us to gaze at the photo of Woody in his Intensive Care Unit hospital bed (image courtesy Woody's brother Greg), we take solace in seeing a glimmer of a smile and some sparkle in his eyes. If you know Woody--and even if you don't--please take a moment to send healing vibes his way in the hope his recovery will be swift and complete.


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


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